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  • 51.
    Bjurenstedt, Anton
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    On the influence of imperfections on microstructure and properties of recycled Al-Si casting alloys2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    There are great energy savings to be made by recycling aluminium; as little as 5% of the energy needed for primary aluminium production may be required. Striving to produce high quality aluminium castings requires knowledge of microstructural imperfections, which is extra important when casting recycled aluminium that generally contains higher levels of imperfections compared to primary aluminium. Imperfections include amongst others Si, Fe, and Mn as well as oxides. Si is needed for castability, but it may also initiate fracture. There are different types of Fe-rich intermetallics influencing properties of castings, generally in a negative direction. Oxides constitute cracks and they are elusive because they are difficult to quantify.

    This thesis aims to increase knowledge about imperfections in recycled aluminium castings originating from alloying elements and the melt. Experiments were performed in advanced laboratory equipment, including X-radiographic imaging during solidification and in-situ tensile testing in a scanning electron microscope. Experiments were also performed at industrial foundry facilities.

    The experiments showed that the nucleation temperature of primary α-Fe intermetallics increased with higher Fe, Mn, and Cr contents. Primary α-Fe are strongly suggested to nucleate on oxides and to grow in four basic morphologies. Lower nucleation frequency of α-Fe promoted faster growth and hopper crystals while higher nucleation frequency promoted slower growth rates and massive crystals. Results also showed that a decrease in the size of the eutectic Si and plate-like β-Fe intermetallics improved tensile properties, foremost the elongation to fracture. In β-Fe containing alloys the transversely oriented intermetallics initiated macrocracks that are potential fracture initiation sites. In alloys with primary α-Fe foremost clusters of intermetallics promoted macrocracks. In fatigue testing, a transition from β-Fe to α-Fe shifted the initiation sites from oxides and pores to the α-Fe, resulting in a decrease of fatigue strength. Oxides in Al-Si alloys continue to be elusive; no correlations between efforts to quantify the oxides and tensile properties could be observed.

  • 52.
    Bjurenstedt, Anton
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Casari, Daniele
    Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Mathiesen, Ragnvald H.
    Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
    Dahle, Arne K.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    In-situ study of morphology and growth of primary α-Al(FeMnCr)Si intermetallics in an Al-Si alloy2017Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 130, s. 1-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Morphology and growth of primary α-Al(FeMnCr)Si intermetallics have been studied in-situ during solidification of a commercial secondary aluminum alloy employing X-radiographic imaging combined with deep-etching. The α-Al(FeMnCr)Si intermetallics were found to nucleate primarily on surface oxides, and the continued growth yielded both rhombic dodecahedrons and elongated rod-like morphologies. Both morphologies were observed as hopper and massive types, where the hopper intermetallics had the higher growth rates. The growth rate, which determines the type, appears to be linked to nucleation frequency; higher nucleation frequency promoted massive types and lower nucleation frequency promoted hopper intermetallics. 

  • 53.
    Bjurenstedt, Anton
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Dahle, Arne
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    The effect of Fe-rich intermetallics on crack initiation in cast aluminium: an in-situ tensile study2019Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 756, s. 502-507Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To evaluate the role of Fe-rich intermetallics on crack initiation, two fully modified Al-Si alloys, one containing plate-like β-Fe and the second containing primary α-Fe intermetallics, were investigated by in-situ tensile testing in the scanning electron microscope. In the first alloy, large plate-like β-Fe intermetallics oriented parallel to the test direction were the first to crack at an elongation of about 1.8%. More transversely oriented intermetallics caused crack initiation in the matrix which linked up with the final fracture. In the second alloy, the cracking of α-Fe intermetallics initiated at an elongation of about 0.9%. It is concluded that large α-Fe intermetallics crack first and that clusters of α-Fe are the most potent crack initiation sites.

  • 54.
    Bjurenstedt, Anton
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Jarfors, Anders
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    On the complexity of the relationship between microstructure and tensile properties in cast aluminum2015Inngår i: International Journal of Modern Physics B, ISSN 0217-9792, Vol. 29, nr 10-11, artikkel-id 1540011Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The relationship between microstructure and mechanical properties in cast aluminium alloys is very complex. This relationship is also strongly affected by the casting process and melt handling. In the current study the mechanical properties were investigated and correlated with microstructural features such as porosity, Fe-rich particles, SDAS, Si-length. Process quality measures such as bifilm index, density index, and sludge factor were also investigated. The aim of the work was to understand the critical interactions between material microstructure and process quality in the development of high performance materials.

  • 55.
    Bjurenstedt, Anton
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Jarfors, Anders
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    The effects of Fe-particles on the tensile properties of Al-Si-Cu alloys2016Inngår i: Metals, ISSN 2075-4701, Vol. 6, nr 12, artikkel-id 314Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of Fe-rich particles has been a topic for discussion in the aluminum casting industry because of the negative impact they exert on the mechanical properties. However, there are still contradictions on the effects of various morphologies of Fe-particles. In this study, microstructural characterization of tensile tested samples has been performed to reveal how unmodified and modified Fe-rich particles impact on the tensile behavior. Analysis of additions of Fe modifiers such as Mn and Cr, showed higher amounts of primary Fe-rich particles (sludge) with increased porosity and, as result, degraded tensile properties. From the fracture analysis of tensile tested HIPed samples it could be concluded that the mechanical properties were mainly governed by the Fe-rich particles, which were fracturing through cleavage, not by the porosity.

  • 56.
    Bjurenstedt, Anton
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Liljenfors, Tomas
    Assessment of Quality when Delivering Molten Aluminium Alloys Instead of Ingots2013Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 765, s. 266-270Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recycled aluminium alloys manufactured at Stena Aluminium, in Älmhult, Sweden, are delivered in special designed transport containers, called thermoses. Thermoses are best described as an insulating layer protected by a steel cover with a heat loss of about 5 degrees/h. Three thermoses are transported by a truck, giving the possibility for a total capacity of about 24 tonnes delivered aluminium just-in-time to the foundry. By delivering a full load of liquid aluminium, about 2 tonnes of carbon dioxide emissions are saved, compared with delivering ingots. The aim of the paper is to assess the quality benefits, in terms of inclusions sedimentation and mechanical properties, assured by delivering aluminiummelts instead of ingots. The results indicate that materials produced by just-in-time melt delivery have slightly improved quality compared to ingots. The trends are explained in terms of quality, density and bifilm indexes, based on microstructural observations as well as tensile test data analysis.

  • 57.
    Bogdanoff, Toni
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Development of aluminium-silicon alloys with improved properties at elevated temperature2017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Aluminium-silicon alloys have gained increasing market share in the automotive and aerospace industry because of increased environmental demands. These alloys have a high strength-to-weight ratio, good corrosion resistance, castability and recycling potential. However, variations in properties and limited performance at elevated temperature are restricting these alloys from use at elevated temperatures. During the last decades, researchers have investigated ways to improve the properties at elevated temperatures. However, the effect of some transition elements is not well understood. The aim of this work is to investigate the aluminium-silicon alloys with addition of cobalt and nickel for high temperature applications. Tensile testing and hardness testing were conducted on samples produced by directional solidification in a Bridgman furnace with condition generating a microstructure corresponding to that obtained in high pressure die casting, i.e. SDAS ~ 10 µm. The results show that cobalt and nickel improve the tensile properties up to 230 °C.

  • 58.
    Bogdanoff, Toni
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Dahle, Arne K.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Effect of Co and Ni Addition on the Microstructure and Mechanical Properties at Room and Elevated Temperature of an Al–7%Si Alloy2018Inngår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 12, nr 3, s. 434-440Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increasing environmental demands are forcing the automotive industry to reduce vehicle emissions by producing more light-weight and fuel efficient vehicles. Al–Si alloys are commonly used in automotive applications because of excellent castability, high thermal conductivity, good wear properties and high strength-to-weight ratio. However, most of the aluminium alloys on the market exhibit significantly reduced strength at temperatures above 200 °C. This paper presents results of a study of the effects of Co and Ni in a hypoeutectic Al–Si alloy on microstructure and mechanical properties at room and elevated temperature. Tensile test specimens with microstructures comparable to those obtained in high-pressure die casting, i.e. SDAS ~ 10 µm, were produced by directional solidification in a Bridgman furnace. The results show an improvement in tensile properties up to 230 °C.

  • 59.
    Bogdanoff, Toni
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Riestra, Martin
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Prototyping of a high pressure die cast al-si alloy using plaster mold casting to replicate corresponding mechanical properties2019Inngår i: Minerals, Metals and Materials Series, Springer, 2019, s. 435-442Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Prototyping prior high pressure die casting (HPDC) is used for product/mold design optimization. Plaster mold casting is a cost-efficient prototyping technique providing good surface quality and dimension accuracy, similar to HPDC components. However, the corresponding mechanical properties of a component produced with these two methods are diverging significantly, mainly due to differences in the cooling rate. This work presents a procedure to optimize the plaster mold casting for prototyping to replicate mechanical properties of a commonly used Al-Si alloy (A380). Two commercial alloys with compositions close to the A380 alloy (A356.0 and A360.2) were used. Yield strength was considered as the main design criteria, thus the target mechanical property. Tensile testing results showed that with an optimized T6 heat treatment, not only the yield strength, but also ultimate tensile strength and elongation correspond well to the properties in the HPDC component.

  • 60.
    Bogdanoff, Toni
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Dahle, Arne K.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    The effect of SI content on microstructure and mechanical properties of Al-Si alloy2016Inngår i: La Metallurgia Italiana, ISSN 0026-0843, Vol. 108, nr 6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Al-Si alloys are the most popular casting alloys due to their excellent castability combined with high strengthto-weight ratio. This paper investigates the role of Si content in the range of 6.5 wt. % to 14.4 wt. % on the microstructure and mechanical properties of Al-Si-Mg casting alloys. All alloys were modified with 90-150 ppm Sr. No grain refiner was added. The samples were produced by directional solidification providing a microstructure that corresponds to microstructures found in die castings. From the phase diagram and coupled zone, increasing the Si level up to 14.4 wt. % is expected to start a competition between formation of α- dendrites and a fully eutectic microstructure. However, it is known that Sr-modification shifts the eutectic to higher Si contents. For the lower Si contents, the microstructure of the samples consisted of α-dendrites and a modified Al-Si eutectic. At 12.4 wt. % Si and above, a cellular eutectic microstructure was observed. No primary Si was observed even at 14.4 wt. % Si. The mechanical properties in terms of yield and tensile strength did not vary remarkably as a function of the Si level unlike the elongation to failure that dropped from 12 % at 6.5 wt. % Si to nearly 6 % at 14.4 wt. % Si; but still the material is exhibiting an elongation to failure that is far higher than normally expected.

  • 61.
    Borkar, Hemant
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Jarfors, Anders
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    In-situ EBSD study of deformation behavior of Al-Si-Cu alloys during tensile testing2015Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 84, s. 36-47Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study deals with the microstructural aspects of the deformation behavior in Al-Si-Cu alloy A380. This has been carried out with in-situ tensile testing coupled with EBSD analysis. The alloy specimens having different microstructures with two different secondary dendrite arm spacing (SDAS) of 9 µm and 27 µm were produced by the unique gradient solidification method. The study of misorientation distribution and texture evolution was performed with different tools in EBSD analysis. The texture was not significantly affected by deformation in both types of alloy specimens. With increase in the deformation, the microstructures are characterized by degradation of EBSD patterns and generation of substructures including low angle boundaries (LABs) and high angle boundaries (HABs). In both the microstructures with low and high SDAS, the boundaries were concentrated around eutectic phases; however this behavior was more pronounced at higher SDAS. The increase in the fraction of LABs with deformation was much higher in the microstructure with higher SDAS than with lower SDAS. This localized strain concentration was especially attributed to the large and elongated eutectic Si particles and Fe-rich intermetallics. The lower mechanical properties obtained at higher SDAS are the result of inhomogeneous strain distribution in the microstructure.

  • 62.
    Borkar, Hemant
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Jarfors, Anders
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Microstructure analysis of Al-Si-Cu alloys prepared by gradient solidification technique2015Inngår i: International Journal of Modern Physics B, ISSN 0217-9792, Vol. 29, nr 10-11, artikkel-id 1540015Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Al–Si–Cu alloys were cast with the unique gradient solidification technique to producealloys with two cooling rates corresponding to secondary dendrite arm spacing (SDAS) of ∼9 and ∼27 μm covering the microstructural fineness of common die cast components.The microstructure was studied with optical microscopy and scanning electronmicroscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electronbackscattered diffraction (EBSD). The alloy with higher cooling rate, lower SDAS, hasa more homogeneous microstructure with well distributed network of eutectic and intermetallicphases. The results indicate the presence of Al–Fe–Si phases, Al–Cu phases andeutectic Si particles but their type, distribution and amount varies in the two alloys withdifferent SDAS. EBSD analysis was also performed to study the crystallographic orientationrelationships in the microstructure. One of the major highlights of this study is theunderstanding of the eutectic formation mechanism achieved by studying the orientationrelationships of the aluminum in the eutectic to the surrounding primary aluminumdendrites.

  • 63.
    Borkar, Hemant
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, India.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Microstructure, texture and mechanical properties of al alloy a380 prepared by directional solidification method2019Inngår i: Manufacturing Sciences and Technologies IX: 9th International Conference on Manufacturing Science and Technology (ICMST 2018), Trans Tech Publications, 2019, Vol. 287, s. 18-23Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The mechanical properties of Al-Si alloys are affected by several microstructural features such as secondary dendrite arm spacing (SDAS), size and shape of eutectic Si-particles, presence of intermetallics as well as by porosity. In the current study, Al-Si-Cu alloy A380 was prepared by a unique directional solidification method to produce samples with two different SDAS of 9 μm and 27 μm. The lower solidification rate resulted in larger SDAS, larger grain size, larger eutectic Si and larger intermetallics including Fe-rich β phase. The microstructure with higher solidification rate was found to be finer and more homogeneous with smaller eutectic Si and intermetallics. The specimen with larger SDAS exhibited stronger texture than the one with smaller SDAS. The specimen with smaller SDAS showed improved mechanical properties including YS, UTS and ductility. 

  • 64.
    Brillo, J.
    et al.
    Deutsches Zentrum für Luft- und Raumfahrt, Institut für Raumsimulation, Köln, Germany.
    Egry, I.
    Deutsches Zentrum für Luft- und Raumfahrt, Institut für Raumsimulation, Köln, Germany.
    Matsushita, Taishi
    Royal Institute of Technology, Dep. of Mater. Science and Eng, Stockholm, Sweden.
    Density and surface tension of liquid ternary Ni-Cu-Fe alloys2006Inngår i: Zeitschrift fuer Metallkunde/Materials Research and Advanced Techniques, Vol. 97, nr 1, s. 28-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density and surface tension of liquid Ni-Cu-Fe alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of an electromagnetic levitator, an optical densitometer, and an oscillating drop tensiometer. 

    At temperatures above and below the liquidus point, density and surface tension are linear functions of temperature. The concentration dependence of the density is significantly influenced by a third-order (ternary) parameter in the volume, while the surface tensions can be derived from the thermodynamic potentials (E)G of the binary phases alone.

  • 65.
    Burman, Erik
    et al.
    Department of Mathematics, University College London, London, United Kingdom.
    Hansbo, Peter
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Larson, Mats G.
    Department of Mathematics and Mathematical Statistics, Umeå University, Umeå, Sweden.
    Massing, André
    Department of Mathematics and Mathematical Statistics, Umeå University, Umeå, Sweden.
    Zahedi, Sara
    Department of Mathematics, KTH Royal Institute of Technology, Stockholm, Sweden.
    A stabilized cut streamline diffusion finite element method for convection–diffusion problems on surfaces2020Inngår i: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 358, artikkel-id 112645Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We develop a stabilized cut finite element method for the stationary convection–diffusion problem on a surface embedded in Rd. The cut finite element method is based on using an embedding of the surface into a three dimensional mesh consisting of tetrahedra and then using the restriction of the standard piecewise linear continuous elements to a piecewise linear approximation of the surface. The stabilization consists of a standard streamline diffusion stabilization term on the discrete surface and a so called normal gradient stabilization term on the full tetrahedral elements in the active mesh. We prove optimal order a priori error estimates in the standard norm associated with the streamline diffusion method and bounds for the condition number of the resulting stiffness matrix. The condition number is of optimal order for a specific choice of method parameters. Numerical examples supporting our theoretical results are also included. 

  • 66.
    Bäckman, Jonas
    et al.
    Högskolan i Jönköping, Tekniska Högskolan.
    Svensson, Ingvar L
    Högskolan i Jönköping, Tekniska Högskolan.
    Influence of ingate system design on mechanical properties for a cast A1-10Si-0.38Mg alloy1999Rapport (Annet vitenskapelig)
    Abstract [sv]

    In this work the influence of the ingate system design on the as-cast mechanical properties of an Al-10Si-0.38Mg alloy have been clarified. The Weibull distribution has been seen to describe the spread in mechanical properties very well. The Weibull modulus has therefore been used as a measure of the soundness of an ingate system. Different ingate systems were investigated, including: expanding systems, pressurised systems, systems with and without filter, systems with different designs of the connection between the downsprue and the runner, and systems with and without an additional pocket at the end of the runner. The modification index of the microstructure was also measured in order to investigate if the spread in data is more dependent on the modification index than on the ingate system design. The results showed that a high Weibull modulus is more dependent on the ingate system design than on the modification index of the microstructure. The ultimate tensile strength was not significantly affected by the ingate system design, while the fracture elongation seemed to be more dependent on the melt quality than on the ingate system design. The Weibull modulus indicates that expanding systems are better than pressurised systems, and that the use of a filter in the runner is very beneficial. An additional pocket at the end of the runner has no beneficial effect when using a filter. The connection between the downsprue and the runner should have a rounded bend and the change in cross-section between the downsprue and the runner should be chamfered and not sharp.

  • 67.
    Bäckman, Jonas
    et al.
    Högskolan i Jönköping, Tekniska Högskolan.
    Svensson, Ingvar L
    Maeda, Yasuhiro
    Evaluation of filter parameters from direct observations of metal flow in aluminium castings1999Rapport (Annet vitenskapelig)
    Abstract [en]

    The potential in mechanical properties for aluminium casting alloys are in many casting processes not fully utilised. One reason is the defect formation in the casting process. The defects could be oxide films, introduced during mould filling, and pore formation. This investigation has been focused on how the gravity mould filling could be controlled by using filter in the ingate system and the how the pressure drop over the filter can be evaluated.

    In gravity casting the metal flow velocity usually reaches several metres per second. Direct observations have shown that filters improve mould filling during casting. Additionally, filters cause a pressure loss, which decreases the speed of the metal and gives a smoother filling.

    In this paper, mould-filling experiments were recorded directly by a video camera through a transparent ceramic glass. Two different types of ceramic filters, reticulated foam filters and extruded filters with 10, 20 and 30 pores per inch and 100 and 300 cells per square inch respectively, were investigated. The influence of active filter area and filter size on the flow reduction has also been investigated. As the casting temperature influences the viscosity of the liquid metal, the pressure loss over the filter was evaluated at various temperatures.

    Using parameters for calculating flow loss caused by filter can help when designing ingate systems containing filters. The filter parameters can be used in two ways, either to control the speed of the metal or to design the active filter area in a way that the melt flux is not affected. Proper parameters are also important for computer simulations of mould filling. The parameters evaluated from these experiments have been used in computer simulation of mould filling and the results have been compared with experiments.

  • 68.
    Bäckman, Jonas
    et al.
    Högskolan i Jönköping, Tekniska Högskolan.
    Svensson, Ingvar L
    Maeda, Yasuhiro
    Influence of filter on the mould filling of aluminium melts in vacuum-sealded moulds1999Rapport (Annet vitenskapelig)
    Abstract [en]

    The influence of filters on the mould filling behaviour has been investigated by direct observation experiments. The ingate system was moulded in a vertically parted vacuumsealed sand mould. How the filter in general, and how different filter locations, filter coarseness, active filter area and filter length influence the mould filling has been clarified. The direct observation method is a very powerful way to learn how different ingate system designs and filter conditions affect the mould filling. During mould filling the melt behaviour was recorded by a video camera through a glass wall, from which still images are presented. The general effect of filters is a better filling of the ingate system prior to the filter, and a reduction of the melt velocity, which in turn give smoother filling after the filter. Initially, the downsprue is completely filled at an early stage of the filling due to the back-pressure from the filter. The back-pressure is built up as a result of friction in the filter. An early filling of the downsprue prevents the melt from entraining oxide films or air inclusions. Secondly, the filling of the runner is improved by the use of a filter. The better filling of the runner is mainly an effect of the decreased velocity of the melt. The reduction of the melt velocity results in reduced surface turbulence and less splashing. Reduced surface turbulence and splashing of the melt prevents incorporation of oxide films and air in the melt, which has an overall beneficial effect on the quality of the castings. The location of the filter has been found to play an important role in the filling soundness.

  • 69.
    Bäckman, Jonas
    et al.
    Högskolan i Jönköping, Tekniska Högskolan.
    Svensson, Ingvar L
    Maeda, Yasuhiro
    Mould filling observations of aluminium melts in vacuum-sealed sand moulds1999Rapport (Annet vitenskapelig)
    Abstract [en]

    In order to clarify how the ingate system design influences the mould filling behaviour of aluminium melts in vertically parted vacuum-sealed moulds, some direct observation experiments have been made. A detailed study of how the design of each component in the ingate system affects the mould filling behaviour has been made. The effect of different designs on downsprue-runner connections, runners and end-wall of the runners as well as the effect of wall friction was investigated. The mould filling process was studied through a glass wall and recorded by a video camera. Still images from the videotape are presented and evaluated. The direct observation method has been found to be a very powerful way to follow the melt behaviour during mould filling. To ensure a good filling of the downsprue the melt level in the pouring basin has to be above a certain level from the time when the stopper is removed and during the whole filling sequence. A perpendicular connection between the downsprue and the runner gives a larger flow loss than a rounded type. Due to the larger flow loss the perpendicular connection results in an earlier filling of the downsprue. A tapered runner results in almost simultaneous filling of the specimens compared to a runner with no tapering. On the other hand the tapered runner gives a more divergent melt front which increase the free melt surfaces in contact with air. An additional pocket at the end of the runner has a beneficial effect on the mould filling. A sharp angled pocket is better than a more rounded type. Decreasing the wall thickness increases the flow loss due to wall friction, and causes more significant heat losses.

  • 70. Campbell, John
    et al.
    Svidró, József Tamás
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Svidró, Judit
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Molding and Casting Processes2017Inngår i: ASM Handbook, Volume 1A: Cast Iron Science and Technology / [ed] Doru M. Stefanescu, Materials Park, Ohio: ASM International, 2017, s. 189-206Kapittel i bok, del av antologi (Fagfellevurdert)
  • 71.
    Cannmo, Patrik
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    An interface model based on damage coupled to slip and dilatation1998Inngår i: Fracture from defects: Proceedings of the 12th Bienniel Conference on Fracture - ECF, held in Sheffield, U.K., 14-18 September 1998, West Midlands, U.K.: Engineering Materials Advisory Services , 1998, s. 957-962Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The mesomechanics behavior of a polycrystalline microstructure subjected to creep and constant strain rate loadings is investigated. The analysis is based on a Voronoi polygonization strategy for the generation of grains, that are bonded to each other via interfaces along the grain boundaries. A new constitutive model is proposed for the rate-dependent debonding along these interfaces, whereby damage is kinetically coupled to viscoplastic slip and dilatation. The paper may be viewed as generalizing the rate-independent model used in Cannmo et al. (1995).

  • 72.
    Cannmo, Patrik
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Simulering och optimering.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik.
    Svensson, Linnea
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik.
    Svensson, Ingvar L
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik.
    Stress-Strain Modelling Influenced by Porosities in Cast Aluminium Alloys2006Konferansepaper (Fagfellevurdert)
  • 73.
    Carlberg, Torbjörn
    et al.
    Mid Sweden University, Sundsvall, Sweden.
    Jarfors, Anders
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    On vertical drag defects formation during direct chill (DC) casting of aluminum billets2014Inngår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 45, nr 1, s. 175-181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During air-slip direct chill casting of aluminum billets, one of the major defects occurring includes traces along the billet called vertical drags (VDs). If the VDs are too deep or too many, then they cause scraping of the billets. As in the subsequent extrusion process, the surface quality is known to impair both the productivity and quality of the profiles. In cast-house practice, many theories circulate about the causes of VD defects and how to avoid them, but in the literature, no thorough treatments have been made to explain this phenomenon. In the current study, the outer appearance, structure around, and compositions at the defects are analyzed. A theory for the formation of the defects, their cause, and how their appearance is coupled to different alloy types is presented. The segregation in the vicinity of the defects is discussed based on deformation of semisolid materials and coupled to Reynolds dilatancy ingranular materials. The theory can explain differences between 6063 and 6005 alloys.

  • 74. Casselgren, J.
    et al.
    Hällstig, E.
    Leisner, Peter
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning - Ytteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Robusta inbyggda system.
    True Ground Speed Sensor (TGSS)2009Konferansepaper (Annet vitenskapelig)
  • 75.
    Cedersund, Elisabet
    et al.
    Högskolan i Jönköping, Hälsohögskolan, HHJ, Avd. för beteendevetenskap och socialt arbete. Högskolan i Jönköping, Hälsohögskolan, HHJ. Kvalitetsförbättringar, innovationer och ledarskap inom vård och socialt arbete.
    Brunnberg, Elinor
    Att studera välfärd på nytt sätt2007Inngår i: Välfärdspolitik i praktiken: Om perspektiv och metoder i forskning, Uppsala: NSU Press , 2007, s. 7-19Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 76.
    Ceschini, L.
    et al.
    University of Bologna.
    Morri, A.
    University of Bologna.
    Toschi, S.
    University of Bologna.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Room and high temperature fatigue behaviour of the A354 and C355 (Al-Si-Cu-Mg) alloys: Role of microstructure and heat treatment2016Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 653, s. 129-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Al-Si-Mg alloys are widely used in the automotive industry for the production of engine components. Due to the new stringent emissions standards, these components undergo highertemperatures than in the past; as a result, alloys with higher thermal stability, such as the Al-Si-Cu-Mg, are currently under investigation.The present paper aims at widening the knowledge on the relationship between room temperature (RT) and high temperature fatigue behaviour of A354 and C355 alloys and their microstructural features, in particular, secondary dendrite arm spacing (SDAS) and intermetallic compounds. Samples for fatigue characterization were hot isostatic pressed, aiming to avoid the effect of solidification defects.The results of microstructural analyses and rotating bending fatigue tests highlighted that (i) SDAS influences room temperature fatigue behaviour of the peak-aged A354 and C355 alloys, while its effect on the overaged alloys at high temperature is negligible; (ii) fatigue cracks nucleated mostly from large intermetallic compounds; (iii) at room temperature, C355 alloy is characterized by higher fatigue strength (151 and 135. MPa for fine and coarse SDAS, respectively) in comparison to A354 alloy (133 and 113. MPa); after overaging and testing at high temperature, the behaviour of the two alloys is comparable. A good correlation between ultimate tensile strength and fatigue resistance was found, independent of microstructure and aging condition.

  • 77.
    Ceschini, Lorella
    et al.
    University of Bologna, SMETEC Department.
    Boromei, Iuri
    Morri, Alessandro
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Material och tillverkning - gjutning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik.
    Svensson, Ingvar L
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Material och tillverkning - gjutning.
    Microstructure, tensile and fatigue properties of the Al–10%Si–2%Cu alloy with different Fe and Mn content cast under controlled conditions2009Inngår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 209, nr 15-16, s. 5669-5679Artikkel i tidsskrift (Fagfellevurdert)
  • 78.
    Ceschini, Lorella
    et al.
    SMETEC Dept. University of Bologna, Bologna, Italy.
    Boromei, Iuri
    SMETEC Dept. University of Bologna, Bologna, Italy.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Svensson, Ingvar
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Effect of Fe content and microstructural features on the tensile and fatigue properties of the Al-Si10-Cu2 alloy2012Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 36, s. 522-528Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As the automotive industry has to meet the requirements of fuel efficiency and environmental concerns, the use of aluminium alloys is steadily increasing. A number of papers have been published about the correlation between microstructure and mechanical properties of the widely used A356/A357 aluminium alloys, while relatively few data are available on others hypoeutectic Al-Si alloys, such as Al-Si-Cu alloys with higher Si content. In this work the effect of different amounts of Fe and Mn on the tensile and fatigue behaviour of the AlSi10Cu2 casting alloy was studied. The reason of this study comes from the fact that cast components are mostly made by secondary Al alloys that inevitably contain Fe, which in turn forms intermetallic compounds, negatively affecting the mechanical behaviour of the alloy. Fatigue specimens were subjected to hot isostatic pressing (HIP) before tests, in order to eliminate the internal pores (gas pores and interdendritic shrinkages) and therefore to solely investigate the effect of microstructural features, rather than solidification defects, on the fatigue propagation stage. The microstructural characterization of the alloy was carried out by optical and scanning electron microscopy. Proof and ultimate tensile strength, as well as fatigue life of the investigated alloy were greatly enhanced by high Fe and Mn content, which reduced the micro-crack propagation rate; on the contrary Fe, without Mn, negatively affected the elongation to failure.

  • 79.
    Ceschini, Lorella
    et al.
    Department of Industrial Engineering (DIN), Alma Mater Studiorum–University of Bologna, Bologna, Italy.
    Dahle, Arne
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Gupta, Manoj
    Department of Mechanical Engineering, National University of Singapore, Singapore.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Jayalakshmi, S.
    Department of Mechanical Engineering, Bannari Amman Institute of Technology (BIT), Sathyamangalam, India.
    Morri, Alessandro
    Interdepartmental Center for Industrial Research-Advanced Mechanics and Materials (CIRI-MAM), Alma Mater Studiorum–University of Bologna, Bologna, Italy.
    Rotundo, Fabio
    Interdepartmental Center for Industrial Research-Advanced Mechanics and Materials (CIRI-MAM), Alma Mater Studiorum–University of Bologna, Bologna, Italy.
    Toschi, Stefania
    Department of Industrial Engineering (DIN), Alma Mater Studiorum–University of Bologna, Bologna, Italy.
    Singh, R. Arvind
    Department of Aeronautical Engineering, Bannari Amman Institute of Technology (BIT), Sathyamangalam, India.
    Aluminum and Magnesium Metal Matrix Nanocomposites2017Bok (Annet vitenskapelig)
    Abstract [en]

    The book looks into the recent advances in the ex-situ production routes and properties of aluminum and magnesium based metal matrix nanocomposites (MMNCs), produced either by liquid or semi-solid state methods. It comprehensively summarizes work done in the last 10 years including the mechanical properties of different matrix/nanoreinforcement systems. The book also addresses future research direction, steps taken and missing developments to achieve the full industrial exploitation of such composites. The content of the book appeals to researchers and industrial practitioners in the area of materials development for metal matrix nanocomposites and its applications.

  • 80.
    Ceschini, Lorella
    et al.
    Department of Industrial Engineering (DIN), Alma Mater Studiorum-University of Bologna, V.le Risorgimento 4, 40136 Bologna, Italy.
    Jarfors, Anders
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Morri, A.
    Department of Industrial Engineering (DIN), Alma Mater Studiorum-University of Bologna, V.le Risorgimento 4, 40136 Bologna, Italy.
    Rotundo, F.
    Interdepartmental Center for Industrial Research-Advanced Mechanics and Materials (CIRIMAM), Alma Mater Studiorum-University of Bologna, V.le Risorgimento 4, 40136 Bologna, Italy.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Toschi, S.
    Department of Industrial Engineering (DIN), Alma Mater Studiorum-University of Bologna, V.le Risorgimento 4, 40136 Bologna, Italy.
    High temperature tensile behaviour of the A354 aluminum alloy2014Inngår i: Materials Science Forum, Vol. 794-796, s. 443-448Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high temperature tensile behaviour of the A354 casting aluminum alloy was investigated also evaluating the influence of secondary dendrite arm spacing (SDAS). Cast specimens were produced through a gradient solidification equipment, obtaining two different classes of SDAS, namely 20-25 µm (fine microstructure) and 40-50 µm (coarse microstructure). After hot isostatic pressing and T6 heat treatment, the samples underwent mechanical characterization both at room and high temperature (200 °C). Results of tensile tests and hardness measurements were related to the microstructural features and fractographic characterization, in order to investigate the effect of microstructure and high temperature exposure on the mechanical behaviour of the alloy.

  • 81.
    Ceschini, Lorella
    et al.
    Bologna University.
    Jarfors, Anders
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Morri, Alessandro
    Bologna University.
    Rotundo, Fabio
    Bologna University.
    Toschi, Stefania
    Bologna University.
    Influence of SDAS on the high temperature tensile behavior of the C355 Al alloy2014Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 783-786, s. 228-233Artikkel i tidsskrift (Fagfellevurdert)
  • 82.
    Ceschini, Lorella
    et al.
    Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Italy.
    Morri, Alessandro
    Department of Industrial Engineering, University of Bologna, Italy.
    Toschi, Stefania
    Department of Industrial Engineering, University of Bologna, Italy.
    Bjurenstedt, Anton
    Swerea SWECAST, Jönköping, Sweden.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Influence of sludge particles on the fatigue behavior of Al-Si-Cu secondary aluminium casting alloys2018Inngår i: Metals, E-ISSN 2075-4701, Vol. 8, nr 4, artikkel-id 268Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Al-Si-Cu alloys are the most widely used materials for high-pressure die casting processes. In such alloys, Fe content is generally high to avoid die soldering issues, but it is considered an impurity since it generates acicular intermetallics (β-Fe) which are detrimental to the mechanical behavior of the alloys. Mn and Cr may act as modifiers, leading to the formation of other Fe-bearing particles which are characterized by less harmful morphologies, and which tend to settle on the bottom of furnaces and crucibles (usually referred to as sludge). This work is aimed at evaluating the influence of sludge intermetallics on the fatigue behavior of A380 Al-Si-Cu alloy. Four alloys were produced by adding different Fe, Mn and Cr contents to A380 alloy; samples were remelted by directional solidification equipment to obtain a fixed secondary dendrite arm spacing (SDAS) value (~10 µm), then subjected to hot isostatic pressing (HIP). Rotating bending fatigue tests showed that, at room temperature, sludge particles play a detrimental role on fatigue behavior of T6 alloys, diminishing fatigue strength. At elevated temperatures (200◦C) and after overaging, the influence of sludge is less relevant, probably due to a softening of the α-Al matrix and a reduction of stress concentration related to Fe-bearing intermetallics.

  • 83.
    Ceschini, Lorella
    et al.
    University of Bologna, Italy.
    Morri, Alessandro
    University of Bologna, Italy.
    Toschi, Stefania
    University of Bologna, Italy.
    Boromei, Iuri
    University of Bologna, Italy.
    Bjurenstedt, Anton
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Al-Si-Cu alloys for high pressure die casting: Influence of Fe, Mn, and Cr on room temperaturemechanical properties2016Inngår i: La Metallurgia Italiana, ISSN 0026-0843, nr 6, s. 77-80Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Al-Si-Cu alloys with high Fe content are widely employed in high pressure die casting (HPDC). Even if Feis usually considered an impurity in secondary aluminum alloys, leading to the formation of harmfulintermetallic compounds, it helps in mitigating or eliminating the problem of die soldering. As a result,secondary Al alloys with Fe content of about 1 wt% are commonly employed for the production of HPDCcastings. Aiming to change the morphology of harmful Fe-bearing phases towards less detrimentalmorphologies, proper alloying elements may be added to the alloys. Mn and Cr (both present in thealuminum scrap), as instance, are reported to prevent from the formation of the acicular β-Al5FeSi phase,leading to the formation of more compact and polygonal intermetallics. Such phases are usually referredto as “sludge” particles. The influence of sludge particles on mechanical properties of Al -Si-Cu castings isstill under investigation. The present work aims at evaluating the effect of impurities (Fe, Mn and Cr)typically present in secondary Al alloys on the microstructure and mechanical properties of the A380 (Al -Si-Cu) alloy. Samples with different Fe, Mn and Cr content were produced and processed through adirectional solidification equipment to obtain specimens with controlled SDAS (~10 μm). Hardness androtating bending fatigue tests were carried out at room temperature. Mechanical properties of the alloyswere then related to the microstructure, analyzed by optical and scanning electron microscopy.

  • 84.
    Ceschini, Lorella
    et al.
    University of Bologna, Italy.
    Morri, Alessandro
    University of Bologna, Italy.
    Toschi, Stefania
    University of Bologna, Italy.
    Johansson, Sten
    Linköping University.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Microstructural and mechanical properties characterization of heat treated and overaged cast A354 alloy with various SDAS at room and elevated temperature2015Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 648, s. 340-349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of the present study was to carry out a microstructural and mechanical characterization of the A354 (Al-Si-Cu-Mg) cast aluminum alloy. The effect of microstructure on the tensile behavior was evaluated by testing samples with different Secondary Dendrite Arm Spacing, (SDAS) values (20-25 mu m and 50-70 mu m for fine and coarse microstructure, respectively), which were produced through controlled casting conditions. The tensile behavior of the alloy was evaluated both at room and elevated temperature (200 degrees C), in the heat treated and averaged (exposure at 210 degrees C for 41 h, after heat treatment) conditions. Optical, scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) were used for microstructural investigations. Experimental data confirmed the significant role of microstructural coarseness on the tensile behavior of A354 alloy. Ultimate tensile strength and elongation to failure strongly increased with the decrease of SDAS. Moreover, solidification rate influenced other microstructural features, such as the eutectic silicon morphology as well as the size of the intermetallic phases, which in turn also influenced elongation to failure. Coarsening of the strengthening precipitates was induced by overaging, as observed by STEM analyses, thus leading to a strong reduction of the tensile strength of the alloy, regardless of SDAS. Tensile properties of the alloy sensibly decrease at elevated temperature (200 degrees C) in all the investigated heat treatment conditions. (C) 2015 Elsevier B.V. All rights reserved.

  • 85.
    Ceschini, Lorella
    et al.
    University of Bologna, Italy.
    Morri, Alessandro
    University of Bologna, Italy.
    Toschi, Stefania
    University of Bologna, Italy.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Johansson, Sten
    Linköping University.
    Effect of microstructure and overaging on the tensile behaviour at room and elevated temperature of C355-T6 cast aluminum alloy2015Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 83, s. 626-634Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present study was focused on the microstructural and mechanical characterization of the Al–Si–Cu–Mg C355 alloy, at room and elevated temperature. In order to evaluate the influence of microstructural coarseness on mechanical behavior, samples with different Secondary Dendrite Arm Spacing (SDAS) (20–25 μm for fine microstructure and 50–70 μm for coarse microstructure), were produced through controlled casting conditions. The tensile behavior of the alloy was evaluated at T6 condition and at T6 with subsequent high temperature exposure (41 h at 210 °C, i.e. overaging), both at room and elevated temperature (200 °C). Microstructural investigations were performed through optical and electron microscopy.

    The results confirmed the important role of microstructure on the tensile behavior of C355 alloy. Ultimate tensile strength and elongation to failure strongly increased with the decrease of SDAS. Larger SDAS, related to lower solidification rates, modify microstructural features, such as eutectic Si morphology and size of the intermetallic phases, which in turn influence elongation to failure. Overaging before tensile testing induced coarsening of the strengthening precipitates, as observed by STEM analyses, with consequent reduction of the tensile strength of the alloy, regardless of SDAS. A more sensible decrease of tensile properties was registered at 200 °C testing temperature.

  • 86.
    Ceschini, Lorella
    et al.
    University of Bologna.
    Morri, Alessandro
    University of Bologna.
    Toschi, Stefania
    University of Bologna.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Messieri, Simone
    Ducati Motor Holding .
    The influence of cooling rate on microstructure, tensile and fatigue behavior of heat treated Al-Si-Cu-Mg alloys2017Inngår i: Liquid metals and alloys: From structure to industrial applications / [ed] Lars Arnberg, Franco Bonollo and Roberto Montanari, Trans Tech Publications, 2017, s. 81-92Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Al-Si-Mg alloys are commonly employed for the production of automotive castings. In view of the recent stringent emissions standards and consequent engine downsizing, these components must withstand higher temperatures and stresses than in the past. In this regard, the heat treatable quaternary Al-Si-Cu-Mg alloys gained particular interest in recent years, due to their superior mechanical properties and higher thermal stability. The present research activity was addressed to evaluate the influence of cooling rate on microstructure and consequently on room temperature tensile and fatigue behaviour of the A354 and C355 alloys. Samples for mechanical tests were produced under controlled cooling rates, in order to induce different secondary dendrite arm spacing (SDAS) values, classified as fine (20-25μm) and coarse (50-70μm). The experimental results showed that the cooling rate strongly influences the type, size and morphology of intermetallic particles. The presence of coarse intermetallic phases, mostly Fe-based, observed in coarse SDAS specimens, was reported to strongly affect ultimate tensile strength (UTS), elongation to failure and fatigue strength of both the investigated alloys. A correlation between UTS and fatigue resistance was found, independent of microstructural coarseness.

  • 87. Chedid, Michel
    et al.
    Belov, Ilja
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning - Ytteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Robusta inbyggda system.
    Leisner, Peter
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning - Ytteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Robusta inbyggda system.
    Experimental Analysis and Modelling of Textile Transmission Line for Wearable Applications2007Inngår i: International Journal of Clothing Science and Technology, ISSN 0955-6222, E-ISSN 1758-5953, Vol. 19, nr 1, s. 59-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose – The paper seeks, by means of measurement and modelling, to evaluate frequency dependent per-unit-length parameters of conductive textile transmission line (CTTL) for wearable applications and to study deterioration of these parameters when CTTL is subjected to washing.

    Design/methodology/approach – The studied transmission line is made of Nickel/Copper (Ni/Cu) plated polyester ripstop fabric and is subjected to standard 60°C cycle in a commercial off-the-shelf washing machine. The per-unit-length parameters (resistance and inductance) and characteristic impedance of the line are extracted from measurements before and after washing. Using the measurement data an equivalent circuit is created to model the degradation of the line. The circuit is then integrated in a three-dimensional transmission line matrix (TLM) model of the transmission line.

    Findings – Both an electrical equivalent circuit and a TLM model are developed describing the degradation of the conductive textile when washed. A severe deterioration of the electrical parameters of the line is noticed. Experimental and modelling results are in good agreement in the addressed frequency band.

    Research limitations/implications – Analysis is performed for frequencies up to 10?MHz. The developed TLM model can be used to conduct parametric studies of the CTTL. To counteract the degradation of the line, protective coating is to be considered in further studies.

    Originality/value – This paper extends knowledge of the subject by experimental and simulation-based characterization of the CTTL when subjected to washing cycles.

  • 88.
    Chedid, Michel
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning - Ytteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Robusta inbyggda system.
    Tomicic, Daniel
    Leisner, Peter
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning - Ytteknik. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Robusta inbyggda system.
    Evaluation of Conductive Textile for Wearable Computer Applications2006Inngår i: The IMAPS Nordic Annual Conference, 2006, s. 220-227Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wearable systems put high demands on wearability and robustness. Conductive fabrics are very likely to be used in wearable systems due to their textile-like characteristics. However conductive fabrics must be able to resist environmental stresses (wearing, laundering, etc.) in the same way as clothing in order to fully comply with the requirements.

    A demonstrator, TxWear, was constructed to exploit conductive fabrics in building a conductive textile transmission line for intermodular communication and power transmission (DC power line communication bus), thus eliminating the need for cables between the modules. The hardware modules are connected to the conductive line through connectors from textile industry, i.e., snap fasteners. Different types of conductive fabrics (Ni/Cu plated polyester fabrics and stainless-steel based elastic ribbon) were evaluated and compared according to their conductivity, flexibility and robustness characteristics. The effect of washing on the electrical properties (per-unit-length parameters) of the textile transmission line was studied. Different coating processes, i.e., parylene and silicone coating, were studied and evaluated in order to isolate and enhance the robustness of the conductive textile. Ni/Cu plated polyester ripstop fabric was found to be not appropriate for wearable applications, while conductive elastic ribbon showed good robustness to laundry induced stresses.

  • 89.
    Chernyakov, A. E.
    et al.
    RAS, SHM RandE Center, St. Petersburg, Russian Federation.
    Aladov, A. V.
    RAS, SHM RandE Center, St. Petersburg, Russian Federation.
    Belov, Ilja
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Belov, V. F.
    Mordovian State University, Saransk, Russian Federation.
    Zakgeim, A. L.
    RAS, SHM RandE Center, St. Petersburg, Russian Federation.
    Modeling of Temperature Distribution Induced by Thermo-Mechanical Deformation of High-Power AlInGaN LED Arrays2019Inngår i: THERMINIC 2019 - 2019 25th International Workshop Thermal Investigations of ICs and Systems, Institute of Electrical and Electronics Engineers Inc. , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Thermo-mechanical deformation, thermal resistance, and lateral temperature distribution were experimentally studied for a high-power AlGaInN LED chip-on-board array at three different input powers. A fullscale CFD model of the LED assembly was developed and correlated with the temperature and average thermal resistance measurements to enable prediction of the temperature distribution on the surface of a thermally deformed LED assembly. Application of the thermal resistance partitioning approach to thermal modeling of the deformed LED assemblies was discussed. It can be useful for design engineers for estimation of the temperature distribution across the deformed LED array, at the minimum number of temperature measurements required for model calibration.

  • 90.
    Chernyakov, Anton E.
    et al.
    SHM R&E Center, RAS, St.Petersburg, Russia.
    Aladov, Andrey V.
    SHM R&E Center, RAS, St.Petersburg, Russia.
    Belov, Ilja
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Zakgeim, Alexander L.
    SHM R&E Center, RAS, St.Petersburg, Russia.
    Thermal resistance and temperature distribution in blue and white high-power LED arrays2017Inngår i: Proceedings of the 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC), 2017, IEEE, 2017, s. 1-4, artikkel-id Code 132094Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Thermal resistance and temperature distribution for high-power AlGaInN LED chip-on-board arrays in blue and white versions were measured by different methods and tools. The p-n junction temperature was determined through measuring a temperature-dependent forward voltage drop on the p-n junction, at a low measuring current after applying a high heating current. Furthermore, the infrared thermal imaging technique was employed to obtain the temperature map for the test object. A steady-state 3D computational model of the experimental setup was created including temperature-dependent power dissipation in the LED chips and partitioned interfacial thermal resistance between the heatsink and the LED array. Simulations of the heat transfer in the LED array were performed to further investigate temperature gradients observed in the measurements.

  • 91.
    Cheung, Ching Chi
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik.
    Semi-automated process planning and cost estimation of turned components based on CATIA V5 Machining2008Independent thesis Advanced level (degree of Magister), 20 poäng / 30 hpOppgave
    Abstract [en]

    To be more competitive in the market, many companies are trying to speed up the quotation process and quote more attractive prices. Therefore, they have identified a need for support in the quotation process in order to reduce the quotation lead-time and ensure a higher level of accuracy in the cost estimations. The Quotation Calculator, an application program, has been developed as part of the degree thesis which was carried out at AB Norrahammars Mekaniska Verkstad, NMW 2006/07. This Quotation Calculator can be operated to calculate the material and manufacturing costs of a new product.

    NMW has recently acquired licenses for CATIA V5, Dassault Systems, for the purpose of making process planning and NC-programming more efficient. NMW wants to generate the data needed from the machining module for the cost calculations. Hence this project was initiated in order to extract data from CATIA V5 for further use in Quotation Calculator or other computer system in NMW.

    This work has resulted in a system developed with a common hosted programming language to extract and transfer information. The system retrieves model geometry from CAD and information on process planning from CAM, then matches the information in the application for the purpose of cost estimation. The system once developed, is supposed to be used for every new product. For this approach, the relationship of the data from CATIA V5 and the Quotation Calculator has been analyzed.

    Within this thesis, the focus is on production cost estimation. The method used here is programming in Visual Basic Editor to extract information from the machining module in CATIA V5 and then import them to Microsoft Excel. With standard operations, tables of data and several inputs, the cost calculation and hence the quotation process can be automatically implemented. This work has been generated with the Quotation Calculator. With the correct input data to process planning and this new quotation system, the machining time and the costs can be estimated more accurately and easier. The time and cost information is made available for decision making. As a result, the lead time for the quotation process will be shortened and a relatively more attractive price can be quoted to the customers.

  • 92.
    Christina, Keller
    et al.
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Informatik.
    Wass, Sofie
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Informatik.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Zetterlind, Madelene
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell organisation och produktion.
    Jarfors, Anders
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Vomacka, Peter
    Hackås Precision Foundry.
    Structured knowledge transfer through online education: Mutual benefits for academia and industry2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Scientists are required to disseminate the results of research to the society and companies participating in research projects. The dissemination procedure normally consists of seminars, scientific and layman journal contributions, and conferences that generally are not flexible and timely enought to capture industrial needs. In an effort to accelerate knowledge transfer and technology implementation to sustain and improve competitiveness, Jönköping University has developed a one-year online master programme in cast metals and processes in collaboration with the industry. The collaboration includes development of the curriculum, case studies, lectures and study visits. To explore the development process, we performed interviews and a survey with participating students/professionals, teachers and industrial partners. Our results show that a profound two-way knowledge transfer took place, and that course content and teaching were highly relevant to the industry. Furthermore, industry and academia engaged in new joint research collaborations. Consequently, we hypothesize that the procedure for structured knowledge transfer can be implemented in materials education at advanced level to foster engagement between university, industry and society.

  • 93.
    Constantin, Therese
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Maskinteknik.
    Konceptframtagning av testinstrument för vattendetektion baserad på MIP2010Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Water is vital for all life on earth. But it can also be dangerous, even fatal, if it is polluted water. 60 percent of child mortality can directly be deduced to dirty water. Not only developing countries are affected, even in the western world epidemics are breaking out by partake or bathing in dirty/polluted water.

    MIP, Molecularly Imprinted Polymers, is a biosensor technology that can provide faster and more reliable response than the current methods of water analysis. It is also cheaper and due to that more samples can be taken and analyzed. These three variables can reduce the number of patients due to polluted water are detected faster and appoint of necessary measures can be done faster.

    This project searches for the design of an automated sample tool based on MIP techniques. The Concepts must express innovation, high quality and clarity. The instrument should be used both in laboratory and in the field.

    The project has resulted in one concept. The concept is based on the one construction of internal components that is as low height as possible (20 centimeters) and is slightly wider than its depth (40 vs. 30 centimeters). MIP-and NIP containers are located by one of the short side and the battery is near the edge of the front side. The placement is designed to facilitate the loading and exchange.

    The concept answers against all of the demands and two of three wishes.  Also the concept is designed after the further user. The further user has also been involved during the process of the concept design. The development of the concept start with the questions from the brainstorming “What will the user feel when they lay their eyes of the product/instrument and uses is?” The ides and thoughts were to ides sketches. They also used in the evaluation of the same sketches. The most exalting ides develop in to three concepts, and in evaluations, with help from further user, with kansei and discussions. The evaluation showed that one of the concepts was adaptable for further development.

    The concept is smooth and has areas for hold. The user is self looking and searching for the optimal hold. The instrument has none parts that extend from the body and can damage the user. The instruments components that the user need to exchange is placed in a box that by automatic shouts out. The aces to this I controlled by a touch screen. One the touch screen is a hand scanner that is used to lock and unlock the instrument. With a window the process of the analyses is showed. That rice the reliability, lift the functions, give a high-tech and a hero feeling and are fun for the users.

  • 94.
    Danno, A.
    et al.
    Singapore Institute of Manufacturing Technology.
    Wong, C. C.
    Singapore Institute of Manufacturing Technology.
    Tong, S.
    Singapore Institute of Manufacturing Technology.
    Jarfors, A.
    Singapore Institute of Manufacturing Technology.
    Nishino, K.
    Toyota Central Research and Development Labs. Inc., Nagakute, Aichi, Japan.
    Furuta, T.
    Toyota Central Research and Development Labs. Inc., Nagakute, Aichi, Japan.
    Effect of cold severe deformation by multi directional forging on elastic modulus of multi functional Ti+25mol% (Ta,Nb,V)+(Zr,Hr,O) alloy2010Inngår i: Materials & Design, ISSN 0261-3069, Vol. 31, nr SUPPL. 1, s. S61-S65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new and unique beta-titanium alloy (Ti. +. 25. mol% (Ta,Nb,V). +. (Zr,Hr,O) has interesting properties such as low elastic modulus, high strength and high elastic deformability as well as Invar and Elinvar properties. These properties have been successfully realized for the round wire or rods by cold working process but not enough for the sheet made by the cold rolling.To improve the mechanical properties of the alloy sheet, the effect of cold severe deformation on the elastic modulus and microstructure of the alloy sheet was experimentally investigated. The samples were processed using the multi directional forging (MDF) and cold plain rolling.The elastic modulus of the alloy sheet which was cold rolled after MDF was lower than that of cold rolled sheet without MDF. The severe cold plastic deformation by MDF was also effective for obtaining isotropic elastic modulus and very fine grain size (∌1ÎŒm) of sheet after plain rolling. The prototype sheet with low elastic modulus (60-65. GPa), high strength (1100. MPa) and high ductility (total elongation more than 10%) was successfully made in the laboratory test by combining MDF and plain rolling at room temperature. © 2009 Elsevier Ltd.

  • 95.
    Davidsson, Karin
    et al.
    SP, Technical Research Institute of Sweden.
    Karlsson, Ingvar
    SP, Technical Research Institute of Sweden.
    Leisner, Peter
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning - Ytteknik.
    Bobert, Magnus
    SP, Technical Research Institute of Sweden.
    Blomqvist, Per
    SP, Technical Research Institute of Sweden.
    Safety test methods for EV batteries2010Inngår i: World Electric Vehicle Journal, ISSN 2032-6653, Vol. 4, s. 414-420Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of the present paper is to share our experience in battery safety testing and risk analysis from arecent project called BLIXT, which had the objective to speed up the progress of the paradigmatic shifttoward electric vehicles (EV). The batteries in question have been three different configurations of lithiumionbatteries (LiFePO4). The tests have involved fire, crash tests and sort circuit.

  • 96.
    Deflorian, F.
    et al.
    University of Trento.
    Rossi, S.
    University of Trento.
    Zanella, Caterina
    University of Trento.
    Fedel, M.
    University of Trento.
    Stress corrosion cracking (SCC) failure in marine areas of fixed guards for climbing2015Inngår i: Corrosion Engineering, Science and Technology, ISSN 1478-422X, E-ISSN 1743-2782, Vol. 50, nr 6, s. 462-466Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work studies the particular mechanism of environmental stress corrosion cracking (SCC) that has been described to interest stainless steel products, like climbing anchors, installed in sea areas. The failure analysis of several broken anchors was carried out. The samples were collected in different parts of the world, always from climbing structures close to the sea. The analysis confirmed the stress corrosion mechanism of degradation, giving also important information about the specific environments causing the metal fracture. These results are in agreement with a few previous works about this subject and are in the frame of the larger topic of SCC of austenitic stainless steel at room temperature. Moreover, some corrosion tests were carried out on stainless steel samples simulating the operation conditions, after contamination with electrolytes at different concentration. The tests are performed in order to better understand the degradation mechanism and to evaluate the influence of some environmental parameters over the susceptibility to SCC. With these experimental data, a possible interpretation model has been proposed together with some reasonable solutions for the material selection process, considering the problem's characteristics and the multiple alternatives available nowadays for climbing materials.

  • 97.
    Diaconu, Lucian Vasile
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Sjögren, Torsten
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Skoglund, Peter
    Scania CV AB.
    Diószegi, Attila
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    A molibdén hatása az öntöttvasak termomechanikus hőfárasztási tulajdonságaira.2013Inngår i: Banyaszati es Kohaszati Lapok - Kohaszat, ISSN 0005-5670, Vol. 146, nr 1, s. 13-17Artikkel i tidsskrift (Fagfellevurdert)
  • 98.
    Ding, X.
    et al.
    Singapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore.
    Jarfors, A. E. W.
    Singapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore.
    Lim, G. C.
    Singapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore.
    Shaw, K. C.
    Singapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore.
    Liu, Y. C.
    Singapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore.
    Tang, L. J.
    Institute of Microelectronics, 11 Science Park Road, Singapore Science Park II, Singapore 117685, Singapore.
    A study of the cutting performance of poly-crystalline oxygen free copper with single crystalline diamond micro-tools2012Inngår i: Precision engineering, ISSN 0141-6359, E-ISSN 1873-2372, Vol. 36, nr 1, s. 141-152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A study was carried out to investigate the crystallographic effects on the performance of cutting poly-crystalline oxygen free copper C10200 (OFC) with single crystalline diamond (SCD) micro-tools. At both large cutting depth and cross-feed rate, as the micro-tool traversed a grain with a crystallographic orientation less favorable for a stable machining process, the work material in front of the rake face was found to be severely deformed. This may lead to a reduced shear angle, thick chip, striation at the back of the chip, high cutting forces, degraded machined surface and the possibility of burr formation. The results showed minimal variations in the machined surface integrity and cutting forces compared to cut amorphous NiP plating with micro-tools. For a high cutting depth, burrs were also observed due to material deformation and pile-up occurring at the groove edges since the localized stress probably built up in front of the rake face. Cutting strategies were demonstrated to improve the performance of cutting OFC with micro-tools and to generate high aspect ratio micro-pillar arrays.

  • 99.
    Dini, Hoda
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    As-cast AZ91D Magnesium Alloy Properties- Effect of Microstructure and Temperature2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Magnesium and magnesium alloys are used in a wide variety of structural applications including automotive, aerospace, hand tools and electronic industries thanks to their light weight, high specific strength, adequate corrosion resistance and good castability. Al and Zn are the primary alloying elements in commercial Mg alloys and commonly used in automotive industries. AZ91 is one of the most popular Mg alloys containing 9% Al and 1% Zn. Hence, lots of research have been done during last decades on AZ91D. However, the existing data concerning mechanical properties and microstructural features showed large scatter and is even contradictory. This work focused on the correlation between the microstructure and the mechanical properties of as-cast AZ91 alloy. An exhaustive characterization of the grain size, secondary dendrite arm spacing (SDAS) distribution, and fraction of Mg17Al12 using optical and electron backscattered diffraction (EBSD) was performed. These microstructural parameters were correlated to offset yield point (Rp0.2), fracture strength and elongation to fracture. It was understood that the intermetallic phase, Mg17Al12, plays an important role in determining the mechanical and physical properties of the alloy at temperature range from room temperature up to 190oC. It was realized that by increasing the Mg17Al12 content above 11% a network of intermetallic may form. During deformation this rigid network should break before any plastic deformation happen. Hence, increase in Mg17Al12 content resulted in an increase in offset yield point. The presence of this network was supported by study of thermal expansion behaviour of the alloy containing different amount of Mg17Al12. A physically-based model was adapted and validated in order to predict the flow stress behaviour of as-cast AZ91D at room temperature up to 190ºC for various microstructures. The model was based on dislocation glide and climb in a single-phase (matrix) material containing reinforcing particles. The temperature dependant variables of the model were quite well correlated to the underlying physics of the material.

  • 100.
    Dini, Hoda
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    As-cast AZ91D magnesium alloy properties: Effects of microstructure and temperature2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Today, there is an essential need for lightweight, energy-efficient, environmentally benign engineering systems, and this is the driving force behind the development of a wide range of structural and functional materials for energy generation, energy storage, propulsion, and transportation. These challenges have motivated the use of magnesium alloys for lightweight structural systems. Magnesium has a density of 1.74 g/cm3, which is almost 30% less than that of aluminium, one quarter of steel, and almost identicalto polymers. The ease of recycling magnesium alloys as compared to polymers makes them environmentally attractive, but their poor mechanical performance is the primary reason for the limited adoption of these alloys for structural applications.

    The Mg-Al-Zn alloy AZ91D exhibits an excellent combination of strength, die-castability, and corrosion resistance. However, its mechanical performance with regard to creep strength, for example, at evaluated temperatures is poor. Moreover, very little is known about the correlation between its mechanical properties and microstructural features. This thesis aims to provide new knowledge regarding the role played by microstructure in the mechanical performance of the magnesium alloy. The properties/performance of the material in relation to process parameters became of great interest during the investigation.

    An exhaustive characterisation of the grain size, secondary dendrite arm spacing (SDAS) distribution, and fraction of Mg17Al12 was performed using optical and electron backscatter diffraction (EBSD). These microstructural parameters were correlated to the offset yield point (Rp0.2), fracture strength, and elongation to failure of the material. It was proposed that the intermetallic phase, Mg17Al12, plays an important role in determining the mechanical and physical properties of the alloy in a temperature range of room temperature to 190°C by forming a rigid network of intermetallic. The presence of this network was confirmed by studying the thermal expansion behaviour of samples of the alloy containing different amounts of Mg17Al12.

    A physically based constitutive model with a wide validity range was successfully adapted to describe the flow stress behaviour of AZ91D with various microstructures. The temperature-dependent variables of the model correlated quite well with the underlying physics of the material. The model was validated through comparison with dislocation densities obtained using EBSD.

    The influence of high-pressure die-cast parameters on the distortion and residual stress of the cast components was studied, as were distortion and residual stress in components after shot peening and painting. Interestingly, it was found that intensification pressure has a major effect on distortion and residual stresses, and that the temperature of the fixed half of the die had a slight influence on the component's distortion and residual stress.

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