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  • 1.
    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 Alloy2018Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 12, nr 3, s. 434-440Artikel i tidskrift (Refereegranskat)
    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.

  • 2.
    Dini, Hoda
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Andersson, Nils-Eric
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Effect of process parameters on distortion and residual stress of high-pressure die-cast AZ91D components2018Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 12, nr 3, s. 487-497Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a study of distortion and residual stress within a high-pressure die-cast AZ91D component, cast under different processing conditions. The influence of process parameters, i.e., die temperature, cooling time, intensification pressure and first-phase injection speeds, was examined. Distortions were measured using the in-house standard analog quality control fixture. Residual stress depth profiles were measured using a prism hole-drilling method. It was found that the most important process parameter affecting the distortion was intensification pressure and the second most important was temperature difference between the two die halves (fixed and moving side). Tensile residual stresses were found very near the surface. Increasing the intensification pressure resulted in an increased level of tensile residual stresses.

  • 3.
    Ekengård, Johan
    et al.
    Sandvik SRP AB, Svedala, Sweden.
    Diószegi, Attila
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Jönsson, Pär G.
    KTH, Stockholm, Sweden.
    A study of oxygen activities before the start of solidification of cast iron2016Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 10, nr 4, s. 500-515Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The focus of this work was to study dissolved oxygen content and oxygen activities in different cast irons. Plant trials were performed on three occasions for lamellar, compacted and nodular iron melts. The results show that at temperatures close to the liquidus temperature the oxygen activities ranged from 0.03 to 0.1 ppm for lamellar graphite iron (LGI), around 0.02 ppm for compacted graphite iron and 0.001 ppm for spheroidal graphite iron. In addition, it was found that as oxygen activities increase with time after an Mg treatment, the ability to form compacted graphite or nodular graphite in Mg-treated iron melts was lowered. Also, oxygen activity differences up to 0.07 ppm were found for different hypoeutectic iron compositions for LGI at the liquidus temperature. Overall, the observed differences in the dissolved oxygen levels are believed to influence how graphite particles are incorporated into the austenite matrix and how the graphite morphology will be in the cast product.

  • 4.
    Hernando, Juan Carlos
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Elfsberg, Jessica
    Scania CV AB, Södertälje, Sweden.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Dahle, Arne
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Diószegi, Attila
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    The role of primary austenite morphology in hypoeutectic compacted graphite iron alloys2020Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work investigates the role of primary austenite morphology on the eutectic and eutectoid microstructures and the ultimate tensile strength (UTS) in a hypoeutectic compacted graphite iron (CGI) alloy. The morphology of primary austenite is modified by isothermal coarsening experiments in which holding times up to 60 min are applied to the solid–liquid region after coherency. The cooling conditions for the subsequent eutectic and eutectoid reactions are similar. Miniaturized tensile tests are performed to evaluate the UTS. The morphological characteristics related to the surface area of primary austenite, the modulus of primary austenite, Mγ, and the hydraulic diameter of the interdendritic region, DHydID, increase with the cube root of coarsening time. The eutectic and eutectoid microstructures are not significantly affected by the morphology of primary austenite, thus indicating that the morphology of the interdendritic regions does not control the nucleation frequency and growth of eutectic cells or graphite. UTS decreases linearly with the increasing coarseness of primary austenite for similar eutectic and eutectoid microstructures, demonstrating the strong influence of primary austenite morphology on the UTS in hypoeutectic CGI alloys.

  • 5.
    Ramos, A. K.
    et al.
    Santa Catarina State University, Joinville, SC, Brazil.
    Diószegi, Attila
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Guesser, W. L.
    Santa Catarina State University, Joinville, SC, Brazil.
    Cabezas, C. S.
    Tupy, Joinville, SC, Brazil.
    Microstructure of compacted graphite iron near critical shrinkage areas in cylinder blocks2020Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To study the microstructure of CGI near areas prone to shrinkage, a special sample was developed that resembles critical areas in cylinder blocks. Foundry trials were conducted with different magnesium contents and inoculation amounts. Using color etching techniques to follow the solidification sequence, four areas were observed with different macrostructure: (i) direct chill and columnar region near the surface; (ii) small eutectic cells and small intercellular space; (iii) large eutectic cells and large intercellular space; and (iv) eutectic cells with carbides in the last to freeze area. By increasing the amount of inoculation, the size of the eutectic cells in the zone with large eutectic cells (iii) is reduced, and the eutectic cells are now smaller and more evenly distributed through the section. Increasing the magnesium content brings a similar effect. In zone (iv), the samples with less inverse chill formation show smaller shrinkage porosities, which are located in the same regions where the inverse chill are, between the eutectic cells, in the last to freeze areas; they also have higher amounts of spheroidal graphite in the last-to-freeze areas. The amount of inverse chill carbides observed in zone (iv) did not present any clear relation with inoculation levels or magnesium content variations used in the experiments. 

  • 6.
    Raza, Mohsin
    et al.
    School of Innovation, Design and Engineering, Mälardalen University, Eskilstuna, Sweden.
    Svenningsson, Roger
    Swerea SWECAST AB, Jönköping, Sweden.
    Irwin, Mark
    TPC Components AB, Hallstahammar, Sweden.
    Fägerström, Björn
    School of Innovation, Design and Engineering, Mälardalen University, Eskilstuna, Sweden.
    Jarfors, Anders E.W.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Effects of process related variations on fillablity simulation of thin-walled IN718 structures2018Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 12, nr 3, s. 543-553Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulation tools have improved significantly and are now capable of accurately predicting mould filling behavior. The quality of prediction is highly dependent on material properties and set-up of boundary conditions for the simulation. In this work material properties were measured and casting conditions were analyzed to accurately replicate the casting process in simulation. The sensitivity of the predictions to minor process variations commonly found in foundries was evaluated by comparing simulation and cast samples. The observed discrepancies between simulation and cast samples were evaluated and discussed in terms of their dependency on process variations. It was concluded that the simulation set-up was capable of reasonable predictions and could replicate the asymmetry of the filling however did not accurately predict the absolute value of the unfilled area. It was discovered that asymmetric flow due to variations in the orientation of the casting mould during filling could have greater influence on the predictions than the actual variation in fill time. The quality of simulation is dependent on equipment and techniques used in the foundry as well as the metallurgical model to simulate the process. 

  • 7.
    Riestra, Martin
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Bjurenstedt, Anton
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Bogdanoff, Toni
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Ghassemali, Ehsan
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Complexities in the assessment of melt quality2018Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 12, nr 3, s. 441-448Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    If high-performance aluminium castings are to be produced, the melt quality needs to be properly assured. Multiple tests for melt quality assessment exist and have previously been analysed. In most studies, the techniques were used separately. In this work, reduced pressure, fluidity, Prefil and tensile tests were evaluated. A commercial EN 46000 alloy was used as the base material with additions of 25 and 50 wt% machining chips to degrade the melt quality. In reduced pressure and fluidity tests, oxides floated to the top of samples, decreasing the reliability. Bifilm index increased with addition level, but not correspondingly. Density index, Prefil and fluidity tests did not present significant variations, and tensile properties only deteriorated with the 50 wt% addition level. The investigated techniques provided information, but measuring the melt quality reliably remains a challenge.

  • 8.
    Tóth, Judit
    et al.
    University of Miskolc, Miskolc, Hungary.
    Svidró, József Tamás
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Diószegi, Attila
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning. Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Stevenson, David
    ExOne GmbH, Augsburg, Germany.
    Heat absorption capacity and binder degradation characteristics of 3D printed cores investigated by inverse fourier thermal analysis2016Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 10, nr 3, s. 306-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The application of 3D printing techniques is a recently developing area used within foundry technology. Digital production of sand molds and cores eliminates the need for hard tooling, drastically reduces lead times and offers design freedoms not possible in the traditional pattern making. Even though mold and core making technologies are refined from both scientific and practical points of view, casting defects may still occur in the final products. Thus, molding material related casting research is required to generate state-of-the-art methods and understandings to avoid the formation of casting defects. In this paper, a pioneering method is presented which is suitable to determine novel thermophysical and heat transfer properties of various types of molding materials. These properties are strongly connected to the cooling capacity and the gas evolution features of the cores used in casting production. The method is based on temperature measurements inside spherical shaped core sand specimens and evaluated by a special application of Fourier thermal analysis. Temperature measurements were performed in test samples produced by two different 3D core printing systems. The registered temperature data were processed by Fourier thermal analysis to calculate the thermal properties and the decomposition characteristics of the 3D printed cores. The experiments were executed under different heating conditions analogous to aluminium and cast iron production.

  • 9.
    Zamani, Mohammadreza
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Material och tillverkning.
    Seifeddine, Salem
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Material och tillverkning – Gjutning.
    Determination of Optimum Sr Level for Eutectic Si Modification in Al–Si Cast Alloys Using Thermal analysis and Tensile Properties2016Ingår i: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 10, nr 4, s. 457-465Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents a correlation between the depression in eutectic growth temperature as a result of Sr modification and the tensile properties of Al–Si cast alloys. In order to study the role that Sr exerts on the solidification behavior, modification and mechanical properties, controlled solidification experiments including thermal analysis were performed. Using three mold materials for different cooling rates, tensile testing was conducted on Al–Si alloys with various Sr levels (~35–500 ppm). The gradient solidification technique was used to produce directionally solidified tensile test specimens containing low levels of defects. The depression in eutectic Si growth temperature was correlated with the Sr additions and the tensile properties (elongation to failure and tensile strength).

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