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  • 1.
    Bjurenstedt, Anton
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Dahle, Arne
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    The effect of Fe-rich intermetallics on crack initiation in cast aluminium: an in-situ tensile study2019In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 756, p. 502-507Article in journal (Refereed)
    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.

  • 2.
    Ceschini, L.
    et al.
    University of Bologna.
    Morri, A.
    University of Bologna.
    Toschi, S.
    University of Bologna.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Room and high temperature fatigue behaviour of the A354 and C355 (Al-Si-Cu-Mg) alloys: Role of microstructure and heat treatment2016In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 653, p. 129-138Article in journal (Refereed)
    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.

  • 3.
    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
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Microstructural and mechanical properties characterization of heat treated and overaged cast A354 alloy with various SDAS at room and elevated temperature2015In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 648, p. 340-349Article in journal (Refereed)
    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.

  • 4.
    Dini, Hoda
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Svoboda, Ales
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Jönköping, Sweden.
    Andersson, Nils-Eric
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Lindgren, Lars-Erik
    Division of Mechanics of Solid Materials, Luleå University of Technology, Luleå, Sweden.
    Jarfors, Anders E.W.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Optimization and validation of a dislocation density based constitutive model for as-cast Mg-9%Al-1%Zn2018In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 710, p. 17-26Article in journal (Refereed)
    Abstract [en]

    A dislocation density-based constitutive model, including effects of microstructure scale and temperature, was calibrated to predict flow stress of an as-cast AZ91D (Mg-9%Al-1%Zn) alloy. Tensile stress-strain data, for strain rates from 10-4 up to 10-1 s-1 and temperatures from room temperature up to 190 °C were used for model calibration. The used model accounts for the interaction of various microstructure features with dislocations and thereby on the plastic properties. It was shown that the Secondary Dendrite Arm Spacing (SDAS) size was appropriate as an initial characteristic microstructural scale input to the model. However, as strain increased the influence of subcells size and total dislocation density dominated the flow stress. The calibrated temperature-dependent parameters were validated through a correlation between microstructure and the physics of the deforming alloy. The model was validated by comparison with dislocation density obtained by using Electron Backscattered Diffraction (EBSD) technique.

  • 5.
    Diószegi, Attila
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Svensson, Ingvar L
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    On the problems of thermal analysis of solidification2005In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 413-414, p. 474-479Article in journal (Refereed)
  • 6.
    Fjellstedt, J.
    et al.
    Outokumpu Copper R and D, Västerås, Sweden.
    Jarfors, A. E. W.
    Corrosion and Metals Research Institute, Stockholm, Sweden.
    On the precipitation of TiB2 in aluminum melts from the reaction with KBF4 and K2TiF62005In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 413-414, p. 527-532Article in journal (Refereed)
    Abstract [en]

    The divergent reaction between Al and the two salts K2TiF6 and KBF4 are used in the manufacturing of Al-Ti-B master alloys for grain refinement. It is also possible to use the same reaction to make aluminum based metal matrix composites. The formation sequence of TiB2 from the reaction with K2TiF6 and KBF4 is discussed in the view of the formation of a salt/metal emulsion and agglomeration. The highly exothermic reaction with K2TiF6 will aid the formation of an emulsion and Al3Ti form that in a subsequent step transforms into TiB2. It will also support high element transfer efficiency. The reaction with KBF4 causes less heat to evolve and the tendency towards formation of an emulsion and thus lower transfer efficiency resulting in a sluggish formation of AlB2. Simultaneous additions of K2TiF6 and KBF4 increase the transfer efficiency but will cause the formation of stringer defects in a layered structure. © 2005 Elsevier B.V. All rights reserved.

  • 7.
    Fourlakidis, Vasilios
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Swerea Swecast.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    A generic model to predict the ultimate tensile strength in pearlitic lamellar graphite iron2014In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 618, p. 161-167Article in journal (Refereed)
    Abstract [en]

    Varying the carbon contents, chemical composition and solidification rate greatly influences the microstructural morphology in lamellar graphite iron resulting in large variations in material properties. Traditionally, ultimate tensile strength (UTS) is used as the main property for the characterisation of lamellar graphite iron alloys under static loads. The main models found in the literature for predicting UTS of pearlitic lamellar graphite iron are based on either regression analysis on experimental data or on modified Griffith or Hall-Petch equation.

    In pearlitic lamellar graphite iron the primary austenite transformed to pearlite reinforces the bulk material while the graphite flakes which are embedded in an iron matrix reduce the strength of the material. Nevertheless a dominant parameter which can be used to define the tensile strength is the characteristic distance between the pearlite grains defined as the maximum continuous defect size in the bulk material, which in this work is expressed by the newly introduced parameter the Diameter of Interdendritic Space. The model presented here covers the whole spectrum of carbon content from eutectic to hypoeutectic composition, solidified at different cooling rates typical for both thin and thick walled complex shaped castings.

  • 8.
    Ghasemi, Rohollah
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Hassan, Inamul
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Ghorbani, Arvin
    Bodycote Gothenburg, Gothenburg, Sweden.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Austempered compacted graphite iron — Influence of austempering temperature and time on microstructural and mechanical properties2019In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 767, article id 138434Article in journal (Refereed)
    Abstract [en]

    This study investigates the effect of austempering temperature and time on the microstructural and mechanical properties of unalloyed Compacted Graphite Iron (CGI) with an initially ferritic matrix structure. The as-cast CGI samples were first austenitised at 900 °C for 60 min in a furnace, then austempered in a closed salt bath at three austempering temperatures – 275, 325, and 375 °C – for different times; 30, 60, 90, and 120 min. Tensile properties, Brinell, Vickers and Rockwell C hardness values were evaluated for the as-cast and austempered CGI ones. LOM and SEM, EBSD analysis techniques were used for microstructure and phase analysis. A mixture of acicular ferrite and retained austenite was achieved in the austempered CGI samples. In general, a decrease in austempering temperature resulted in a decrease in retained austenite content, corresponding improvements in hardness and tensile strength, and a decrease in elongation values.

    The full text will be freely available from 2021-09-19 00:00
  • 9.
    Ghassemali, Ehsan
    et al.
    School of Mechanical & Aerospace Engineering, Nanyang Technological University and Singapore Institute of Manufacturing Technology (SIMTech).
    Tan, Ming-Jen
    School of Mechanical & Aerospace Engineering, Nanyang Technological University.
    Chua, Beng Wah
    Singapore Institute of Manufacturing Technology (SIMTech).
    Jarfors, Anders E.W.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Lim, S.C.V.
    Materials Engineering, Monash University.
    Grain size and workpiece dimension effects on material flow in an open-die micro-forging/extrusion process2013In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 582, no 10, p. 379-388Article in journal (Refereed)
    Abstract [en]

    The interactive effect of grain size and specimen dimensions on the material flow and microstructural evolution was studied in a progressive open-die microforming process. Particular interest was paid on the effect of the number of grains over the initial specimen thickness, on the evolution of the dead metal zone (DMZ) in the final micro-component's microstructure. Such a DMZ is deemed unfavorable for mechanical properties of the pin. Interestingly, experimental results revealed that the DMZ can be removed at the pin surface by increasing the initial grain size. This behavior was attributed to the role of the strain gradient on the deformation. In the aspects of the forming load and dimensional measurements of the final parts, there were no significant size-effects observed in this process. This is because the neutral plane, which demarcates the two directions of material flow in the open-die forging/extrusion process, determines the amount of material flow towards the die orifice, regardless of the initial grain size.

  • 10.
    Ghatei Kalashami, A.
    et al.
    Isfahan University of Technology, Iran.
    Kermanpur, A.
    Isfahan University of Technology, Iran.
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Najafizadeh, A.
    Isfahan University of Technology, Iran.
    Mazaheri, Y.
    Isfahan University of Technology and Bu-Ali Sina University, Iran.
    Correlation of microstructure and strain hardening behavior in the ultrafine-grained Nb-bearing dual phase steels2016In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 678, p. 215-226Article in journal (Refereed)
    Abstract [en]

    Ultrafine-grained dual phase (DP) steels with different Nb contents (0.00, 0.06 and 0.12 wt%) were produced by cold-rolling followed by intercritical annealing of ferrite/martensite starting microstructure at 770 °C for different holding times. Scanning electron microscopy, equipped with electron backscattered diffraction (EBSD) detector, nanoindentation and tensile testing were used to characterize microstructural evolutions and their correlations to the strain hardening and fracture behavior. EBSD results confirmed the retardation effect of Nb on recrystallization. It was found that the strains stored in the grains and density of geometrically necessary dislocations (GNDs) were increased with the addition of Nb. Strain hardening analysis showed that plastic deformation of the DP steels occurred in three distinct stages, which based on the EBSD results, nanoindentation and fracture analysis, were controlled by microstructural features such martensite volume fraction and size, density of GNDs and individual ferrite and martensite tensile properties.

  • 11.
    Goi, K. L. S.
    et al.
    Ametek, Singapore.
    Butler, D. L.
    Nanyang Technological University, Singapore.
    Jarfors, A. E. W.
    KIMAB, Stockholm, Sweden.
    Yong, J. M. S.
    Singapore Institute of Manufacturing Technology.
    Lim, D. C. S.
    Nanyang Technological University, Singapore.
    Elastic modulus of sintered porous Ti-Si-Zr, using activation by Ti-Si mechanically alloyed powder and TiH2 powder2008In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 475, no 1-2, p. 45-51Article in journal (Refereed)
    Abstract [en]

    A novel biomaterial based on Ti-Si-Zr was developed using the sintering process with a composition targeting at a bulk modulus in the same range as that of human bone, i.e. 10-30 GPa. Control of porosity should also be possible to allow for the promotion osseointegration. The sintering procedure involves the use of mechanically alloyed Ti-Si-powder, and TiH2, to promote bonding, but not consolidation. The effect of porosity on the bulk modulus using compression testing is investigated. The influence of sintering temperature, heating rate, and amount and size of the TiH2-activator on porosity are also investigated. The achievable bulk modulus was in the range of 20-55 GPa at porosity levels ranging from 16% to 54%. Porosity had a profound influence on the bulk modulus, and the choice of appropriate processing conditions enables the creation of an engineered porosity and bulk modulus primarily by varying the sintering temperature and the size of the TiH2-powder particles. © 2007.

  • 12.
    Gu, Y. W.
    et al.
    Singapore Institute of Manufacturing Technology.
    Goh, C. W.
    Singapore Institute of Manufacturing Technology.
    Goi, L. S.
    Singapore Institute of Manufacturing Technology.
    Lim, C. S.
    School of Mechanical and Aerospace Engineering, Nanyang Technological University, Nanyang Avenue, Singapore.
    Jarfors, A. E. W.
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Tay, B. Y.
    Singapore Institute of Manufacturing Technology.
    Yong, M. S.
    Singapore Institute of Manufacturing Technology.
    Erratum: "Solid state synthesis of nanocrystalline and/or amorphous 50Ni-50Ti alloy" (Materials Science Engineering A (2005) vol. 392 (222-228) 10.1016/j.msea.2004.09.025))2005In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 402, no 1-2, p. 349-350Article in journal (Refereed)
  • 13.
    Gu, Y. W.
    et al.
    Singapore Institute of Mfg. Technol..
    Goh, C. W.
    Singapore Institute of Mfg. Technol..
    Goi, L. S.
    Singapore Institute of Mfg. Technol..
    Lim, C. S.
    School of Mechanical/Production Eng., Nanyang Technological University, Nanyang Avenue, Singapore.
    Jarfors, A. E. W.
    Swedish Inst. for Metals Research, Stockholm, Sweden.
    Tay, B. Y.
    Singapore Institute of Mfg. Technol..
    Yong, M. S.
    Singapore Institute of Mfg. Technol..
    Solid state synthesis of nanocrystalline and/or amorphous 50Ni-50Ti alloy2005In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 392, no 1-2, p. 222-228Article in journal (Refereed)
    Abstract [en]

    A nanocrystalline/amorphous 50Ni-50Ti alloy was produced by solid state synthesis via mechanical alloying from elemental Ti and Ni powders. Using X-ray diffraction analysis and transmission electron microscopy techniques, a mechanically induced solid state reaction of 50Ni-50Ti was investigated. Results showed that nanocrystalline and amorphous Ni-Ti phases were obtained after mechanical alloying. The mechanical alloying of 50Ni-50Ti for 270 ks led to the formation of f.c.c. Ni(Ti) solid solution, characterized by a lattice parameter of 0.3558 nm, crystallite size of 14 nm and lattice strain of 0.98%. The particle size decreased with increasing milling time. The crystallite size of mechanically alloyed 50Ni-50Ti powders was substantially refined as the milling proceeded and the lattice strain increased with the milling time. The steady-state crystallite size was approximately 10-15 nm. The internal lattice strain in Ni-Ti alloy led to the disordering and the subsequent formation of amorphous alloy during mechanical alloying. After heat treatment at 1100 °C, the as-milled powders transformed into B2-NiTi phase and a small amount of Ti2Ni phase. © 2004 Elsevier B.V. All rights reserved.

  • 14.
    Jarfors, A.
    et al.
    Casting of Metals, Royal Institute of Technology, Stockholm, Sweden.
    Fredriksson, H.
    Casting of Metals, Royal Institute of Technology, Stockholm, Sweden.
    Froyen, L.
    Department MTM, Katholieke Universiteit Leuven, De Croylaan 2, B-3030 Heverlee, Belgium.
    On the thermodynamics and kinetics of carbides in the aluminium-rich corner of the AlTiC phase diagram1991In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 135, no C, p. 119-123Article in journal (Refereed)
    Abstract [en]

    Aluminium composites have a great potential because of their high strength-to-weight ratio. Carbides will in the future be powerful reinforcements. To be able to manufacture these it is of importance to know the thermodynamic properties and the kinetic limitations. The objective of this investigation is to study the equilibria between the carbides occurring in the AlTiC system as well as the initial precipitation and dissolution behaviour of these carbides. It can be shown that there is a change in stability between TiC and Al4C3, depending on both composition and temperature. To study the nucleation and precipitation behaviour of the carbides in liquid aluminium and aluminium alloys a set of alloys were melted and heated to an appropriate temperature in graphite crucibles. The effect of time and the effect of composition on the chemical reactions involving carbides have been investigated. A theoretical analysis of both the thermodynamics and kinetics was performed, giving a tentative explanation. © 1991.

  • 15. Johansson, Sten
    et al.
    Zeng, Xiao-Hu
    Andersson, Nils-Eric
    Peng, Ru L
    Measurement of average texture of cold-rolled aluminium sheet by electron back-scattering diffraction: a comparison with neutron diffraction2001In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 315, no 1-2, p. 129-135Article in journal (Refereed)
    Abstract [en]

    Measurements of the average texture on sheet of commercial pure aluminium have been performed using neutron diffraction and electron back-scattering diffraction (EBSD). Orientation distribution function maps have been calculated and compared. The results show a good correspondence provided that the data from the EBSD measurements are corrected according to a texture index versus inverted number of measurement procedure. Most errors are probably related to differences in investigated volume and calculation technique and to the fact that the microstructure was difficult for EBSD measurements.

  • 16.
    Kasvayee, Keivan Amiri
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Salomonsson, Kent
    Jönköping University, School of Engineering, JTH, Product Development.
    Sujakhu, S.
    School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
    Castagne, S.
    School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
    Jarfors, Anders E.W.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Strain localization and crack formation effects on stress-strain response of ductile iron2017In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 702, p. 265-271Article in journal (Refereed)
    Abstract [en]

    The strain localization and crack formation in ferritic-pearlitic ductile iron under tension was investigated by in-situ tensile tests. In-situ tensile tests under optical microscope were performed and the onset of the early ferrite-graphite decohesions and micro-cracks inside the matrix were studied. The results revealed that early ferrite-graphite decohesion and micro-cracks inside the ferrite were formed at the stress range of 280–330 MPa, where a kink occurred in the stress-strain response, suggesting the dissipation of energy in both plastic deformation and crack initiation. Some micro-cracks initiated and propagated inside the ferrite but were arrested within the ferrite zone before propagating in the pearlite. Digital Image Correlation (DIC) was used to measure local strains in the deformed micrographs obtained from the in-situ tensile test. Higher strain localization in the microstructure was measured for the areas in which the early ferrite-graphite decohesions occurred or the micro-cracks initiated.

  • 17.
    Kasvayee, Keivan Amiri
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Svensson, Ingvar L.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Olofsson, Jakob
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Jarfors, Anders E.W.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Characterization and modeling of the mechanical behavior of high silicon ductile iron2017In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 708, p. 159-170Article in journal (Refereed)
    Abstract [en]

    This paper investigates the effect of the solidification conditions and silicon content on the mechanical properties of ductile iron and presents empirical models for predicting the tensile behavior based on the microstructural characterizations. Two ductile iron grades of GJS-500-7 and GJS-500-14 were cast with silicon content of 2.36% and 3.71%, respectively. The cast geometry consisted of six plates with different thicknesses that provided different cooling rates during the solidification. Microstructure analysis, tensile and hardness tests were performed on the as-cast material. Tensile behavior was characterized by the Ludwigson equation. The tensile fracture surfaces were analyzed to quantify the fraction of porosity. The results showed that graphite content, graphite nodule count, ferrite fraction and yield strength were increased by increasing the silicon content. A higher silicon content resulted in lower work hardening exponent and strength coefficient on the Ludwigson equation. The results for 0.2% offset yield and the Ludwigson equation parameters were modeled based on microstructural characteristics, with influence of silicon content as the main contributing factor. The models were implemented into a casting process simulation to enable prediction of microstructure-based tensile behavior. A good agreement was obtained between measured and simulated tensile behavior, validating the predictions of simulation in cast components with similar microstructural characteristics.

  • 18.
    Kasvayee, Keivan Amiri
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Salomonsson, Kent
    Jönköping University, School of Engineering, JTH, Product Development. Jönköping University, School of Engineering, JTH. Research area Product Development - Simulation and Optimization.
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Jarfors, Anders E.W.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Microstructural strain distribution in ductile iron: Comparison between finite element simulation and digital image correlation measurements2016In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 655, p. 27-35Article in journal (Refereed)
    Abstract [en]

    This paper presents a study on microstructural deformation of a ferritic–pearlitic ductile iron, utilizing in-situ tensile testing, digital image correlation (DIC) and finite element analysis (FEA). For this purpose, the in-situ tensile test and DIC were used to measure local strain fields in the deformed microstructure. Furthermore, a continuum finite element (FE) model was used to predict the strain maps in the microstructure. Ferrite and pearlite parameters for the FE-model were optimized based on the Ramberg–Osgood relation. The DIC and simulation strain maps were compared qualitatively and quantitatively. Similar strain patterns containing shear bands in identical locations were observed in both strain maps. The average and localized strain values of the DIC and simulation conformed to a large extent. It was found that the Ramberg–Osgood model can be used to capture the main trends of strain localization. The discrepancies between the simulated and DIC results were explained based on the; (i) subsurface effect of the microstructure; (ii) differences in the strain spatial resolutions of the DIC and simulation and (iii) abrupt changes in strain prediction of the continuum FE-model in the interface of the phases due to the sudden changes in the elastic modulus.

  • 19. Källbom, Rikard
    et al.
    Hamberg, K
    Wessén, Magnus
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Björkegren, L-E
    On the solidification sequence of ductile iron castings containing chunky graphite2005In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 413-414, p. 346-351Article in journal (Refereed)
  • 20. Papachristos, V.
    et al.
    Panagoupolos, C.
    Walhström, U.
    Christoffersen, L.
    Leisner, Peter
    Jönköping University, School of Engineering, JTH, Computer and Electrical Engineering.
    Effect of annealing on the structure and hardness of Ni-P-W multilayered alloy coatings produced by pulse plating2000In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 279, no 1-2, p. 217-230Article in journal (Refereed)
  • 21.
    Seifeddine, Salem
    et al.
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Component Technology.
    Johansson, Sten
    Svensson, Ingvar L.
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Component Technology.
    The influence of cooling rate and manganese content on the beta Al5FeSi phase formation and mechanical properties of Al-Si based alloys2008In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 490, no 1-2, p. 385-390Article in journal (Refereed)
  • 22.
    Shanthi, M.
    et al.
    Sch. of Mech. & Aerospace Eng., Nanyang Technological University, Singapore.
    Gupta, M.
    Department of Mechanical Engineering, National University of Singapore.
    Jarfors, A. E. W.
    Sch. of Mech. & Aerospace Eng., Nanyang Technological University, Singapore.
    Tan, M. J.
    Sch. of Mech. & Aerospace Eng., Nanyang Technological University, Singapore.
    Synthesis, characterization and mechanical properties of nano alumina particulate reinforced magnesium based bulk metallic glass composites2011In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 528, no 18, p. 6045-6050Article in journal (Refereed)
    Abstract [en]

    Mg67Zn28Ca5 bulk metallic glass reinforced with 0.66-1.5vol% of nano alumina particulates were successfully synthesized using disintegrated melt deposition technique. Microstructural characterization revealed reasonably uniform distribution of alumina particulates in a metallic glass matrix. The reinforced particles have no significant effect on the glass forming ability of the monolithic glass matrix. Mechanical characterization under compressive loading showed improved micro hardness, fracture strength and failure strain with increase in nano alumina particulate reinforcement. The best combination of strength, hardness and ductility was observed in Mg/1.5vol% alumina composite with fracture strength of 780MPa and 2.6% failure strain.

  • 23.
    Sjölander, Emma
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Artificial ageing of Al–Si–Cu–Mg casting alloys2011In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 528, no 24, p. 7402-7409Article in journal (Refereed)
    Abstract [en]

    The T6 heat treatment is commonly used for gravity cast Al-Si-Cu-Mg alloys. The influence of the alloying elements Cu and Mg and the artificial ageing temperature on the age hardening response were investigated. Artificial ageing was conducted at 170°C and 210°C for various times for three alloys, Al-7Si-0.3Mg, Al-8Si-3Cu and Al-8Si-3Cu-0.5Mg, cast with three different solidification rates (secondary dendrite arm spacing of about 10, 25 and 50μm). The coarseness of the microstructure has a small influence on the yield strength, as long as the solution treatment is adjusted to obtain complete dissolution and homogenisation. The peak yield strength of the Al-Si-Mg alloy is not as sensitive to the ageing temperature as the Al-Si-Cu and Al-Si-Cu-Mg alloys are. The ageing response of the Al-Si-Cu alloy is low and very slow. When 0.5 wt% Mg is added the ageing response increases drastically and a peak yield strength of 380 MPa is obtained after 20 h of ageing at 170°C for the finest microstructure, but the elongation to fracture is decreased to 3%. The elongation to fracture decreases with ageing time in the underaged condition as the yield strength increases for all three alloys. A recovery in elongation to fracture of the Al-Si-Cu-Mg alloy on overageing is obtained for the finest microstructure, while the elongation remains low for the coarser microstructures. The quality index, Q= YS +Kε, can be used to compare the quality of different Al-Si-Mg alloys. This is not true for Al-Si-Cu-Mg alloys, as K depends on the alloy composition. Overageing of the Al-Si-Mg alloy results in a decrease in quality compared to the underaged condition

1 - 23 of 23
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