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  • 1. Ahmadpour, A.
    et al.
    Raiszadeh, R.
    Shahid Bahonar Univ, Dept Met & Mat Sci, Kerman, Iran. Shahid Bahonar Univ, Mineral Ind Res Ctr, Kerman, Iran..
    Doostmohammadi, Hamid
    Shahid Bahonar Univ, Dept Met & Mat Sci, Kerman, Iran. Shahid Bahonar Univ, Mineral Ind Res Ctr, Kerman, Iran..
    Effect of stirring on behaviour of double oxide film defects in A356 aluminium melt2014In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 27, no 4, p. 221-229Article in journal (Refereed)
    Abstract [en]

    The effect of stirring of melt on the behaviour of double oxide film (bifilm) defects in A356 melt was investigated using a reduced pressure test (RPT) technique. The melt was poured from a height into a crucible to introduce bifilms into the melt. The melt was then either remained stagnant or mechanically stirred, and RPT samples were taken from the melt at 8 min intervals. The RPT samples were then characterised by determination of their porosity parameters and examination of the internal surfaces of the pores using a scanning electron microscope. The results showed that stirring of the melt facilitated the diffusion of H in the melt into the atmosphere of the defects and hence accelerated the removal of the defects from the melt by floatation. This effect was attributed to the increase in the stress induced to the defects, which increased the rate of formation of cracks on their layers.

  • 2. Alirezaei, Mohammadamin
    et al.
    Doostmohammadi, Hamid
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Microstructure evolution in cast and equilibrium heat-treated CuZn30-(Si) alloys2016In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 4, p. 222-227Article in journal (Refereed)
    Abstract [en]

    The main object of this work was to investigate the effect of Si addition and heat treatment on the microstructure of CuZn30 alloy. The alloys were prepared by casting and then the chemical composition, microstructure and phases were determined by optical and scanning electron microscope and XRD analysis. The resulting microstructures contained two phases, alpha and beta', with volume fraction depending on silicon content. Increments of Si content led to the formation of a Widmanstatten structure. It was also found that the silicon dissolved completely in alpha + beta phases and the lattice parameters of both alpha- and beta'-phases increased as the Si content increased. Hardness tests showed that hardness of both the as-cast and heat-treated samples increased as the Si content increased, and a significant increment of hardness in heat-treated alloy was due to the formation of a martensite phase.

  • 3. Amirinejhad, S.
    et al.
    Raiszadeh, R.
    Shahid Bahonar Univ Kerman, Dept Met & Mat Sci, Kerman, Iran. Shahid Bahonar Univ Kerman, Mineral Ind Res Ctr, Kerman, Iran..
    Doostmohammadi, Hamid
    Department of Metallurgy and Materials Science and Mineral Industries, Research Centre, Shahid Bahonar University of Kerman, Jomhoori Eslami, Blvd., Kerman, Iran.
    Study of double oxide film defect behaviour in liquid Al-Mg alloys2013In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 26, no 6, p. 330-338Article in journal (Refereed)
    Abstract [en]

    The change in the composition of oxide layers and the possibility of the formation of bonding between the layers of a double oxide film defect when held in Al melts containing 0.7, 1 and 2 wt-%Mg were investigated. The defect was modelled by maintaining two aluminium oxide layers in contact with one another in the melt at 1023 K for times between 5 s and 50 h. Any changes in the composition and morphology of these layers were studied by SEM and energy dispersive X-ray. The results showed that in all the alloys, the initial Al2O3 layer first transformed to MgAl2O4 and then to MgO. These transformations caused the two layers to bond together gradually. The results confirmed that, in all the Al alloys containing 0.3-4.5 wt-%Mg, oxide films have the chance to heal if held in the liquid metal for a long enough period of time.

  • 4.
    Ekström, Madeleine
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    High-temperature corrosion fatigue of a ferritic ductile cast iron in inert and corrosive environments at 700˚C2015In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336Article in journal (Refereed)
    Abstract [en]

    In the present work, low-cycle fatigue testing of a ferritic ductile cast iron named SiMo51 has been carried out in three atmospheres: argon, air and a synthetic diesel exhaust-gas at 700°C. The fatigue life was reduced up to 80% in the worst case. Two crack growth mechanisms were observed and directly linked to oxidation. At weak oxidation, a nodule-to- nodule crack growth occurred. At strong oxidation, crack growth occurred through oxidized material in front of the crack tip. 

  • 5.
    Eliasson, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Interaction behaviour between alumina particles and solidification front and particle behaviour in iron based alloys at deoxidation by Kirkendall effect2007In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 20, no 3, p. 127-130Article in journal (Refereed)
    Abstract [en]

    The present paper deals with interaction phenomena by particles in liquid metals. The interpretation is to make an initial analysis how the model by Kirkendall, for diffusion phenomena in solids, can be used for the analysis of particle behaviour in liquids. Whenever there is an unequal solutal field, insoluble particles may 'move' due to concentration gradients in the liquid and a difference of diffusion rates of the solute atoms. The analysis deals with the following melt/particles interactions: one is the interaction behaviour between the solidification front and the formed slag oxide particles of Al2O3 and the critical velocity for pushing/engulfment at the interface and the other is the movement and clustering of precipitated alumina inclusions around SiO2 or FeO inclusions formed in a steel melt before deoxidation. Despite the uncertainty of the used material constants and the assumed concentration profiles, the results of the present study are in accordance with some shown experimental particle movements.

  • 6.
    Esfahani, Hosein Bartar
    et al.
    Shahid Bahonar Univ Kerman, Sch Engn, Dept Met & Mat Sci, Jomhoori Eslami Blvd, Kerman, Iran..
    Doostmohammadi, Hamid
    Shahid Bahonar Univ Kerman, Sch Engn, Dept Met & Mat Sci, Jomhoori Eslami Blvd, Kerman, Iran..
    Raiszadeh, Ramin
    Shahid Bahonar Univ Kerman, Sch Engn, Dept Met & Mat Sci, Jomhoori Eslami Blvd, Kerman, Iran..
    Decrease in the rate of diffusion of hydrogen through layers of bifilm defects in Al melt in the presence of Sr2016In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 3, p. 179-185Article in journal (Refereed)
    Abstract [en]

    The change in the diffusion rate of H through layers of bifilm defects in Al-0.05 wt% Sr melt was investigated by studying the change in the porosity of samples that were held in furnace for different times, subjected to vibration and then solidified under reduced pressure. The results showed that the vibration accelerated the rate of formation of cracks on the layers of the defects, the rate of diffusion of H into their atmosphere and the rate of consumption of Sr in the melt. These rates decreased gradually as the melt was held in the furnace before applying the vibration. This decrease was attributed to the transformation of alumina to Sr-containing oxides, which caused the strength of the layers to increase and the rate of formation of cracks on them to decrease. This behaviour may have an impact on the increase in porosity of Al castings modified by Sr.

  • 7.
    Esfahani, Hosein Bartar
    et al.
    Shahid Bahonar Univ Kerman, Dept Met & Mat Sci, Kerman, Iran..
    Raiszadeh, Ramin
    Shahid Bahonar Univ Kerman, Dept Met & Mat Sci, Kerman, Iran..
    Doostmohammadi, Hamid
    Shahid Bahonar Univ Kerman, Dept Met & Mat Sci, Kerman, Iran..
    Weibull verification of reduced pressure test as a tool for assessing Al melt quality2017In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 30, no 2, p. 87-95Article in journal (Refereed)
    Abstract [en]

    The credibility of reduced pressure test (RPT) as a substitute for Weibull analysis for benchmarking bifilm defects in Al alloys was confirmed by comparing the RPT parameters (2D and 3D porosity, and Bifilm Index) with the Weibull moduli for UTS values for pure Al and Al-0.05Sr alloys. The porosity of RPT samples was found to have an exponential decay relationship with Weibull modulus. A reasonable trend for Bifilm Index could not be found. 3D porosity of RPT samples was found to be more favourable than 2D porosity or Bifilm Index. Some evidence was also found of connections occurring between the sides of bifilm defects at the surfaces of the fractured tensile test bars of Al-0.05Sr alloy which had a relatively high UTS.

  • 8.
    Korojy, Bahman
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Ekbom, Lars
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    On solidification shrinkage of copper-lead and copper-tin-lead alloys2009In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 22, no 1-4, p. 179-182Article in journal (Refereed)
    Abstract [en]

    Solidification shrinkage is an important concept in achieving sound castings. In the present work solidification shrinkage was studied in copper-lead and copper-lead-tin alloys. A series of solidification experiments was performed under different cooling rates using a dilatometer which was developed for melting and solidification purposes. The volume change was measured during primary solidification and the monotectic reaction. In order to explain the volume-changing results, the sample macrostructures were studied to evaluate gas and shrinkage cavities which were formed during the solidification. Furthermore, the volume fraction of the primary phase during solidification was evaluated in the samples that were quenched from different temperatures below the liquidus temperature. A shrinkage model was used to explain the volume changes during solidification.

  • 9.
    Korojy, Bahman
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    On solidification and shrinkage of brass alloys2009In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 22, no 1-4, p. 183-186Article in journal (Refereed)
    Abstract [en]

    The solidification process was investigated in brass alloys containing a wide range of zinc, between 32.5 and 47.1 wt-%. A series of solidification experiments was performed under different cooling rates using differential thermal analysis (DTA) and a confocal mirror furnace. The cooling rate and the solidification under cooling temperature were evaluated from cooling curves. Furthermore, the peritectic reaction was studied in view of the starting and the ending temperatures and shrinkage behaviour. The volume change was measured in the peritectic alloys using a dilatometer which was developed to investigate the melting and solidification processes. A theoretical analysis was developed to evaluate the volume change effect on the peritectic reaction.

  • 10. Kron, J.
    et al.
    Antonsson, T.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    Air gap formation during solidification in cylindrical castings of pure aluminium and eutectic Al-Si2002In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 14, no 5, p. 275-285Article in journal (Refereed)
    Abstract [en]

    Casting of aluminium and eutectic Al-Si in a cylindrical mould has been performed. The air gap formed between the inner mould wall and the solidified shell was measured throughout the solidification process. Simultaneously the temperature distribution in the metal and the mould was measured. Calculations of the shrinkage of the metal were performed. The shrinkage due to thermal contraction was found to be too small to fit the measurements. A new model for the solidification process and the air gap formation was used, where the effect of the formation and condensation of lattice defects was considered. The condensation of lattice defects was used to explain the shrinkage and the air gap found experimentally.

  • 11. Kron, J.
    et al.
    Bellet, M.
    Ludwig, A.
    Pustal, B.
    Wendt, J.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    Comparison of numerical simulation models for predicting temperature in solidification analysis with reference to air gap formation2004In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 17, no 5, p. 295-310Article in journal (Refereed)
    Abstract [en]

    As a result of its influence on heat transfer between cast part and mould, air gap formation is an important problem for many casting processes. The general explanation for gap formation is that, as a result of stresses and distortions that are created from inhomogeneous cooling, shrinkage of the casting and expansion of the mould occur. In this paper, different thermomechanical approaches are applied to a well defined casting process using three commercial and one in-house codes and their predictions are compared with experimental findings. The experimental data were obtained from the solidification and subsequent cooling of cylindrical castings of eutectic Al-13% Si and ternary Al-7% Si-0.3% Mg alloys. Based on these findings, the major differences between the predictions of the models and the actual formation of the air gap are discussed.

  • 12. Kron, J.
    et al.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Measurements and modelling of air gap formation in Cu-based alloys2005In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 18, no 1, p. 21-28Article in journal (Refereed)
    Abstract [en]

    The formation of an air gap has been experimentally studied during solidification of pure Cu, Cu-Te and Cu-6%Sn in a cylindrical mould. The displacements of the casting and the mould causing an air gap have been measured during solidification and cooling of the casting. The temperature distribution was measured simultaneously. Mathematical modelling has been performed to increase the understanding of the solidification process and the shrinkage of the casting leading to air gap formation. A model, which has been tested in earlier work showing good results for aluminium based alloys, has been applied here to describe air gap formation during solidification of copper based alloys. The model includes the effect of the formation and condensation of vacancies on the solidification process as well as on the material shrinkage resulting in air gap formation. The results from the modelling show a reasonable agreement with the experimental measurements.

  • 13. Kron, J.
    et al.
    Lagerstedt, A.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Measurements and modelling of air gap formation in aluminium based alloys2005In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 18, no 1, p. 29-40Article in journal (Refereed)
    Abstract [en]

    The formation of an air gap has been experimentally studied during solidification of several aluminium based alloys. Air gap widths and temperature distribution have been measured during solidification in a cylindrical mould. The effect of grain refinement on heat transfer and air gap formation has been studied. Mathematical modelling has been performed to increase the understanding of the solidification process and air gap formation. A model was developed for description of air gap formation in alloys solidifying with varying solidification intervals. The model includes the effect of formation and condensation of lattice defects on the solidification process and air gap formation. The calculated shrinkage using this model shows good agreement with the experimental data.

  • 14.
    Lyu, Yezhe
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi. School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, PR China.
    Sun, Yufu
    School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, PR China.
    Liu, Shengxin
    School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, PR China.
    Zhao, Jingyu
    School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, PR China.
    Effect of Tin on Microstructure and Mechanical Properties of Compacted Graphite Iron2015In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 28, no 5, p. 263-268Article in journal (Refereed)
    Abstract [en]

    This experiment investigated the effect of tin in an amount up to 0.121 wt.% on the microstructure and mechanical properties of compacted graphite iron (CGI). Graphite and matrix evolution was emphasized with the help of scanning electron microscopy. The results indicate that Sn in experimental range reduces graphite size. Pearlite quantity would increase with the increasing Sn and reaches over 95% when Sn is greater than 0.057 wt.%. Sn helps to narrow the lamellar spacing of pearlite from sorbitic pearlite (320 nm) to troostitic pearlite (83 nm) when Sn increases from 0.003 wt.% to 0.057 wt.%. Appropriate Sn addition promotes the tensile strength and impact toughness and the samples containing 0.057 wt.% Sn perform the highest values of 410.7 MPa and 9.11 J/cm2, respectively. Elongation declines with increasing Sn content because of the emergence of more pearlite. Samples containing excessive Sn experience sharply deterioration in mechanical properties due brittle cementite.

  • 15.
    Magnusson, Lena
    et al.
    KTH, Superseded Departments, Casting of Metals.
    Adolfi, Sofia
    Fredriksson, Hasse
    A Thermodynamic Analysis of the Inoculation Process in Cast IronIn: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336Article in journal (Refereed)
  • 16.
    Makaya, Advenit
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Variation of nitrogen solubility and mechanism of pore formation during production of porous Fe-Cr-Mn-Si-C material2007In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 20, no 2, p. 73-83Article in journal (Refereed)
    Abstract [en]

    Experiments regarding the synthesis of porous metallic materials were performed by dissolution of nitrogen into molten hypereutectic 77Fe-8Cr-6Mn-5Si-4C (wt-%) and hypoeutectic 79Fe-8Cr-6Mn-5Si-2C alloys, and water quenching. A uniform pore distribution was obtained only for the hypereutectic alloy. To study the effect of the alloy composition and microstructure on the pore distribution, the variation of nitrogen solubility during primary solidification was calculated for both alloys, taking into account the phase composition changes. A mechanism of pore formation is proposed. In the hypereutectic alloy, an increasing nitrogen supersaturation in the melt during primary carbide growth is believed to fuel the growth of nucleated N-2 pores. The primary M7C3 carbides play an essential role in preventing pore coalescence. In the hypoeutectic alloy, a decreasing nitrogen solubility gap between the austenite dendrites and the liquid does not allow extensive pore growth. The absence of primary carbides favours the formation of a single large pore.

  • 17. Mansson, T.
    et al.
    Nilsson, Fred L.
    KTH, Superseded Departments, Solid Mechanics.
    Fatigue life estimation of cast components2001In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 13, no 6, p. 373-378Article in journal (Refereed)
    Abstract [en]

    An engineering method based on fracture mechanics is suggested for life predictions of components of nodular cast iron. The method should be applicable to any structure containing defects which can cause crack initiation. Component testing was performed and the observed results were compared with model predictions. Fatigue crack growth data were obtained by testing on CT specimens even for load ratios R < 0. By accounting for crack closure the R-effect on the growth rates can also be effectively eliminated for this type of material.

  • 18. Mansson, T.
    et al.
    Nilsson, Fred L.
    KTH, Superseded Departments, Solid Mechanics.
    Nodule influence on fatigue crack growth thresholds in nodular cast iron2000In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 12, no 5, p. 319-325Article in journal (Refereed)
    Abstract [en]

    The influence of microstructure i.e. nodules (voids) on the fatigue threshold value in nodular cast iron is numerically investigated. It is qualitatively shown that the fatigue threshold value is unaffected by the individual nodules and that the threshold value is proportional to the bulk Young's modulus. Furthermore it is shown that nodules (voids) do not influence the crack tip conditions (stress-intensity factor and crack tip opening displacement) if the voids do not lie very close to the tip for physically long cracks. It is concluded that linear elastic fracture mechanics is valid for these types of materials and no influence of the nodules need be taken into count for fatigue calculations when dealing with long cracks.

  • 19.
    Muhmond, Haji Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Graphite growth control analysis in high Al cast iron2016In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 5, p. 272-278Article in journal (Refereed)
    Abstract [en]

    High Si and Al cast iron has been investigated experimentally and thermodynamically. Alloys were prepared in the laboratory with low to high Al and Si concentrations. Experiments were performed using Mg treatment of the melt. In another series of experiments, the effect of Ca and Ce in the absence of Mg was studied. The samples were analysed using scanning electron microscope and energy-dispersive X-ray spectroscopy. In alloys with high Al and Si content, the formation of chunky graphite is crucial for control. The effects of Al, Si and inoculants were analysed with the help of thermodynamics. It was found that the activity of oxygen changed due to the high concentrations of Al and Si, which influenced the nucleation of MgO and other oxides in the melt. The oxygen level in the melt determines the graphite morphology.

  • 20.
    Nassar, Hani
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    On the effect of strain on peritectic reactions and transformations in Fe-Ni and Fe-Cu binary alloys2009In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 22, no 1-4, p. 232-235Article in journal (Refereed)
    Abstract [en]

    Differential thermal analysis (DTA) experiments conducted on Fe-Ni and Fe-Cu alloys showed undercooling below the equilibrium peritectic temperatures, T-P. The intervals between the observed liquidus and peritectic temperatures were on average 11 degrees C and 8 degrees C larger than the intervals obtained from equilibrium phase diagrams of Fe-Ni and Fe-Cu respectively. The transformation from delta-Fe to gamma-Fe during the peritectic reaction is associated with density change and strain build up at the delta-Fe/gamma-Fe interface. Thermodynamic calculations showed that by introducing the strain energy at the delta-Fe/gamma-Fe interface, T-P dropped 9 K below its equilibrium value and the increase in the liquidus-to-peritectic temperature interval was in reasonable agreement with the experimental observations. The growth rate of gamma-Fe during a peritectic transformation was calculated based on the strain-induced undercooling in T-P and the results showed partial agreement with observations obtained from CSLM directional solidification experiments conducted earlier on Fe-Ni alloys.

  • 21.
    Ragnarsson, Lars
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Song, Wei
    Ma, Yonglin
    Du, Sichen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Physical and mathematical modelling of argon shroud for protection of steel stream during casting2010In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 23, no 6, p. 368-374Article in journal (Refereed)
  • 22.
    Ranganathan, Sathees
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Makaya, Advenit
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Influence of Mo in the structure of rapidly solidified Fe-Mo-Cr-Mn-Si-C alloy2009In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 22, no 1-4, p. 264-267Article in journal (Refereed)
    Abstract [en]

    An Fe-Mo-Cr-Mn-Si-C alloy was prepared in an induction furnace and was cast into cylindrical rod in a copper mould in castmatic equipment (low pressure casting). A single phase non-equilibrium featureless (no visible microstructures after deep etching) phase was observed over a certain range of thickness of the rod. In this present work, the extent of the featureless phase was studied with different concentrations of Mo (5-25 wt-%) for 5.5 mm diameter of cylindrical rod at a cooling rate of 1100 K s(-1). Light optical microscopy, scanning electron Microscopy and Vickers hardness tests were used to analyse the samples. The amount of the featureless area varies as the Mo content changes and the maximum featureless area was obtained for 7 wt-% of Mo. This single phase featureless structure exhibits very high hardness (>1350 HV) which can be used in many interesting applications with or without suitable heat treatments.

  • 23.
    Svidró, Péter
    et al.
    Jönköping University.
    Diószegi, Attila
    Jönköping University.
    On problems of volume change measurements in lamellar cast iron2014In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 27, no 1, p. 26-37Article in journal (Refereed)
  • 24.
    Tadesse, Abel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Fredriksson, Hasse
    The Effects of Carbon on the Solidification of Nodular Cast Iron– its Study with the help of Linear Variable Differential Transformer and Microstructural Analysis2017In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336Article in journal (Other academic)
    Abstract [en]

    The effect of carbon on the solidification of ductile cast iron (DCI) was studied using linear variable differential transducers (LVDT) and microstructural analysis. Thermal expansion during the eutectic solidification was investigated by using LVDT and temperature measurements in a sand mould. The eutectic volume change was compared with the theoretical calculation. In addition to that, the primary austenite during the solidification was evaluated by using differential thermal analysis (DTA) and the samples undergo a dilatometer experimentation to assess the effect of cooling rates. It was found that the samples show no expansion in the transversal direction due to higher micro-shrinkages in the centre whereas in the longitudinal direction the samples shows expansion until solidifications completed. The theoretical and measured volume changes agree with each other. The austenite fraction and micro-shrinkage pores decrease with increase in carbon content. The nodule count and distribution changes with carbon content. The thermal contraction of DCI is not influenced by the variation in carbon content at lower cooling rate.        

  • 25.
    Tadesse, Abel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The effects of carbon on the solidification of nodular cast iron- its study with the help of linear variable differential transformer and microstructural analysis2018In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 31, no 2, p. 108-117Article in journal (Refereed)
    Abstract [en]

    The effect of carbon on the solidification of ductile cast iron (DCI) was studied using linear variable differential transducers (LVDT) and microstructural analysis. Thermal expansion during the eutectic solidification was investigated by using LVDT and temperature measurements. The eutectic volume change was compared with the theoretical calculation. Furthermore, the primary austenite during solidification was evaluated by using differential thermal analysis and the samples undergo a dilatometer experimentation to assess the effect of cooling rates. It was found that the samples show no expansion in the transversal direction due to higher micro-shrinkages in the centre whereas in the longitudinal direction the samples shows expansion until solidification completed. The theoretical and measured volume changes agree with each other. The austenite fraction and micro-shrinkage pores decrease with increase in carbon content. The nodule count and distribution changes with carbon content. The thermal contraction of DCI is not influenced by carbon content variation at lower cooling rate.

  • 26.
    Tadesse, Abel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Volume change during the solidification of grey cast iron: its relation with the microstructural variation, comparison between experimental and theoretical analysis2017In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, p. 1-12Article in journal (Refereed)
    Abstract [en]

    The expansion/contraction during the solidification of grey cast iron was studied using Linear Variable Differential Transformer (LVDT). The experiments were conducted with and without melt treatment. Two types of inoculant used for melt treatment: ASSC (Si, Ca, Sr & Al) and MBZCAS (Si, Ca, Zr, Ba, Mn & Al). Microstructural investigations carried out to quantify the eutectic cells, undercooled graphite, primary austenite and secondary dendritic arm spacing (SDAS). It was found that the casting shows hardly any shrinkage during early solidification but in the eutectic region, the casting expands until the end of solidification. The measured and the calculated volume changes are close to one another, but the former shows more expansion. The addition of MBZCAS promotes more flake graphite, and ASSC does not increase eutectic cells much. In addition to that, it lowers the primary austenite fraction, promotes more eutectic growth, decreases undercooled graphite and SDAS. As a result, the volume expansion changes in the eutectic region.

  • 27. Tinoco, J.
    et al.
    Delvasto, P.
    Quintero, O.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    Thermal analysis of nodular and lamellar eutectic cast iron under different cooling rates2003In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 16, no 03-jan, p. 53-58Article in journal (Refereed)
    Abstract [en]

    Thermal analysis was performed on neareutectic nodular and lamellar cast iron,alloys under different cooling rates. In a DTA setup, cooling rates from 0.08 K/sec to 0.35 K/sec were used, while in a mirror furnace setup cooling rates up to 55 K/sec were reached. At low cooling rates, the solidification behaviour was analyzed by interrupting the process through quenching. The volume fraction of each phase and substructure was evaluated together with the latent heat at different solidification times. It was observed that the growth rate of the nodules decreases with time. Measurements on the number of nodules indicate that the nucleation rate is constant through the solidification process. The measured latent heat of fusion varies along the solidification process for nodular cast iron but not for lamellar cast iron. This difference in the solidification behaviour may be explained by different diffusion kinetic laws. It was also found that the measured latent heat of fusion decreases when the cooling rate increases. Alloys with nodular graphite showed lower latent heat in comparison with the alloys with lamellar graphite at high cooling rates. This effect is explained by means of thermodynamics of lattice defects, such as vacancies, formed in the austenite and graphite phase during solidification.

  • 28. Yamauchi, A.
    et al.
    Emi, T.
    Seetharaman, Seshadri
    KTH, Superseded Departments, Materials Science and Engineering.
    A mathematical model for prediction of thickness of mould flux film and friction in continuous casting mould2002In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 15, no 4, p. 345-353Article in journal (Refereed)
    Abstract [en]

    A mathematical model of mould flux infiltration and heat transfer through the flux film has been developed. The model considers the effect of static pressure of molten steel, temperature dependency of flux viscosity and determination of liquid flux thickness with pressure gradient. Present model gives the results that agree well with actual plant data such as mould flux consumption, mould friction and the heat transfer. The results of the model give remarkable effect of static pressure of molten steel as follows: decrease of the static pressure causes increase of liquid and total flux film thickness, reduction of heat flux and decrease of friction force on solidified shell.

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