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  • 51.
    Kron, Jenny
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Lagerstedt, Anders
    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.
    Modelling of air gap formation in solidification processing2005In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 58, no 4, p. 531-538Article in journal (Refereed)
    Abstract [en]

    Different models are used today to model air gap formation during a solidification process. In this work air gap modelling is discussed with reference to experimental work with air gap measurements during casting. Thermal and thermomechanical modelling were done with thermal boundary conditions found experimentally. The measured displacements of the mould and the solidifying metal were used in order to check the validity of the simulation results and compare it with reality. The description of the thermal shrinkage and its connection to air gap formation is especially discussed. Al- and Fe-based alloys investigated elsewhere have been used in this work.

  • 52. Lacaze, J.
    et al.
    Greer, A. L.
    Howe, A.
    Ludwig, A.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    Microstructure control by solidification processing - Outcome from a European thematic network2003In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 5, no 02-jan, p. 11-17Article in journal (Refereed)
  • 53.
    Lagerstedt, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Adolfi, Sofia
    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.
    Crack formation during continuous casting of tool steel2005In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 58, no 4, p. 671-678Article in journal (Refereed)
    Abstract [en]

    The formation of cracks has been studied during continuous casting of a tool steel. Experimental work was performed in a continuous slab caster and the position of the cracks was determined as a function of distance from the cooling surface. Numerically calculated temperatures and elastic stresses were combined with experimentally determined thermomechanical data of the cast material in order to predict crack positions. The model was extended to include the effect on the strain from both thermal shrinkage and the shrinkage caused by condensation of vacancies during the solidification process.

  • 54.
    Lagerstedt, 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.
    A model for prediction of cracks in a solidifying shell2005In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 413, p. 37-43Article in journal (Refereed)
    Abstract [en]

    A model coupling temperature and stress calculations with cracking criteria has been developed in order to predict crack positions in a solidifying shell. The model is based on a one-dimensional FDM approach suitable for continuous casting of slabs. The strain/stress model is based on a purely elastic analysis of a solidifying shell giving a straightforward comparison between stresses and crack criteria. This approach makes the model easy to use. The model is numerically evaluated using available material data for Fe-2%Ni with primary ferrite solidification and Fe-10%Ni with primary austenitic solidification. The results of the calculations are discussed and the impact of material behavior as well as process parameters is evaluated. Evaluation of the influence of changes in the heat transfer coefficient shows that the rapid changes introduce stresses large enough to induce crack formation in the solidifying shell.

  • 55.
    Lagerstedt, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Kron, Jenny
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Hailom Yosef, Futsum
    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.
    Measurements and modeling of air gap formation in iron-base alloys2005In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 413, p. 44-51Article in journal (Refereed)
    Abstract [en]

    The formation of an air gap has been experimentally studied during solidification of several iron-based alloys. Air gap widths and temperature distribution have been measured during solidification in a cylindrical water-cooled Cu-mold. Mathematical modeling has been performed to increase the understanding of the solidification process and the air gap formation. A model, developed earlier for Al- and Cu-based alloys, for description of air gap formation in alloys solidifying with varying solidification intervals was tested for Fe-base alloys. The model includes the effect of formation and condensation of lattice defects on the solidification process and the air gap formation. The calculated shrinkage using this model shows good agreement with the experimental data.

  • 56.
    Magnusson, Lena
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Adolfi, Sofia
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    A thermodynamic analysis of the inoculation process in cast iron.2006Report (Other academic)
  • 57.
    Magnusson, Lena
    et al.
    KTH, Superseded Departments, Materials Processing.
    El-Benawy, Talaat
    KTH, Superseded Departments, Materials Processing.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Processing.
    Solidification processing of si, an experimental study on the variation of latent heat (and lattice defects) with the cooling rate2001Report (Other (popular science, discussion, etc.))
  • 58.
    Magnusson, Lena
    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.
    A Thermodynamic Assessment of the Inoculation Process in Al-base Alloys2007In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 60, no 2-3, p. 361-365Article in journal (Refereed)
    Abstract [en]

    The binary Al-Ti and the ternary phase diagrams Al-Ti-B and Al-Ti-C are calculated from normal thermodynamic laws. The calculated phase diagrams are used to discuss the formation of Al3Ti during the cooling process. In the binary Al-Ti phase diagram an undercooling of only 30 K is shown to be necessary to nucleate new crystals of Al3Ti. It is shown that both Al3Ti and TiB2 are formed during cooling of an inoculated Al-melt. TiB2 is more easily nucleated than Al3Ti due to its lower solubility product. Al3Ti is assumed to be nucleated on the TiB2 particles. TiC is not stable at the melting point of aluminium and will decompose into Al4C3 and Al3Ti during cooling. It is suggested that Al3Ti is the active reagent for nucleation of Al.

  • 59.
    Magnusson, Lena
    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.
    Inoculation of Al Alloys with Ti2005In: TRANSACTIONS OF THE INDIAN INSTITUTE OF METALS, 2005, Vol. 58, no 4, p. 553-556Conference paper (Refereed)
    Abstract [en]
    The solubility of Ti in the liquid in equilibrium with Al3Ti is discussed. From this discussion, it is suggested that Al3Ti is the phase nucleating Al. The proposal is based on evaluation of enthalpy and entropy of formation of Al3Ti of experiments reported in literature. The heat of formation was found to be dependent on the processing. The variation of solubility is an effect of lattice defects in Al3Ti. The effect of B on inoculation is discussed. TiB2 acts as an inoculant of Al3Ti and Al is nucleated on Al3Ti.
  • 60. Mahmoudi, J.
    et al.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    Solidification behaviour of rapidly quenched Cu-Sn alloys2000In: Materials transactions, JIM, ISSN 0916-1821, Vol. 41, no 11, p. 1575-1582Article in journal (Refereed)
    Abstract [en]

    A series of solidification experiments using DTA furnace were performed on different Cu-Sn alloys. The undercooling, cooling rates of the liquid and the solid states, solidification times and temperatures were evaluated from the curves. The cooling curves for different samples and alloys were simulated using a FEM solidification program. The heat transfer coefficient and the heat of fusion were evaluated. The calculated fraction of solid formed before quenching has been compared with the experimental result. It was found that the calculated values of the heat of fusion were much lower than the tabulated ones. The fraction of solid was also found to be much higher than those calculated theoretically. It is proposed that a large number of vacancies form during rapid solidification and that they condense during and after the solidification. The influence of these defects on the thermodynamics and solidification of the alloys has been evaluated.

  • 61. Mahmoudi, J.
    et al.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    Thermal analysis of copper-tin alloys during rapid solidification2000In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 35, no 19, p. 4977-4987Article in journal (Refereed)
    Abstract [en]

    A series of solidification experiments using a mirror furnace and a levitation technique were performed on different Cu-Sn alloys. Cooling curves during solidification were registered using a thermocouple of type K connected to a data acquisition system. The undercooling, cooling rates of the liquid and of the solid state, solidification times and temperatures were evaluated from the curves. The samples were found to solidify far below the liquidus temperature. The cooling curves for different samples and alloys were simulated using a FEM solidification program. The heat transfer coefficient, heat of fusion and specific heat were evaluated. It was found that the calculated values of the heat of fusion were much lower than the tabulated ones. The calculated values of the specific heat in the solid state were also found to be much higher than those quoted in the literature, especially for the mirror furnace experiments. The effect of rapid cooling on the thermodynamic state and the solidification process of the alloys has been evaluated. The effect of cooling rate on the formation and condensation of vacancies is discussed. It is proposed that a large number of vacancies form during rapid solidification and that they condense during and after the solidification. The influence of these defects on the thermodynamics and solidification of the alloys has been evaluated.

  • 62. Mahmoudi, J.
    et al.
    Vynnycky, M.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    Modelling of fluid flow, heat transfer and solidification in the strip casting of a copper base alloy - (III). Solidification - a theoretical study2001In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 30, no 3, p. 136-145Article in journal (Refereed)
    Abstract [en]

    A finite-volume model has been developed and applied to analyse the solidification process of pure copper in the mould region of a continuous strip casting machine. The model was produced with the commercial program GFX, which allows this non-linear, turbulent problem to be simulated using a modified version of the k-epsilon turbulence model. The fluid flow, temperature and heat flux distributions in the mould region of the easter were computed. The shape and location of the solidification front were also determined. The effects of operating parameters, such as casting speed, superheat and the assumed values for the latent heal of fusion on the shape and location of the solidification front were investigated.

  • 63. Mahmoudi, J.
    et al.
    Vynnycky, M.
    Sivesson, P.
    Fredriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    An experimental and numerical study on the modelling of fluid flow, heat transfer and solidification in a copper continuous strip casting process2003In: Materials transactions, ISSN 1345-9678, E-ISSN 1347-5320, Vol. 44, no 9, p. 1741-1751Article in journal (Refereed)
    Abstract [en]

    An experimental and numerical study was carried out to investigate the solidification process in a copper continuous strip casting process. Heat flow and solidification process has been experimentally studied. Cooling curves during solidification were registered using a thermocouple of type K connected to a data acquisition system. Temperature measurements in the mould and cooling water were also performed. The numerical model considers a generalized set of mass, momentum and heat equations that is valid for the solid, liquid and solidification interval in the cast. A k - epsilon turbulence model, produced with the commercial program CFX, is used to analyse the solidification process of pure copper in the mould region of the caster. The fluid flow, temperature and heat flux distributions in the mould region of the caster were computed. The shape and location of the solidification front were also determined. The effects of the parameters such as heat transfer coefficient, casting speed, casting temperature. heat of fusion and specific heat on the shape and location of the solidification front and the heat transport at the mould-cast interface were investigated. The predicted temperature and heat flux distributions were compared with experimental measurements, and reasonable agreement was obtained.

  • 64.
    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.
    Production of Fe-Cr-C base foam: theoretical considerations and partical fabrication2005In: Proceedings of the Symposium on "Cellular Metals and Polymers" / [ed] Singer,R.F., Körner, C., Altstädt, V., Münstedt, H., Zürich: Trans Tech Publications , 2005, p. 49-52Conference paper (Refereed)
  • 65.
    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.
    Study on the production of Fe–Cr–Mn–C–Si foam by nitrogen solubility difference between the liquid and solid phases2005In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 413-414, p. 533-537Article in journal (Refereed)
    Abstract [en]

    The feasibility of the production of Fe-base metallic foam by using the nitrogen solubility difference between the liquid and austenite phases has been studied in the Fe-Cr-Mn-C-Si system. Compositions showing a suitable solubility gap for precipitation of gas pores upon solidification have been derived by thermodynamic calculations of the nitrogen solubility in the liquid and solid phases, using the interaction parameters of nitrogen. Small amount of foams were produced for different compositions. The foaming involved dissolution of chromium nitrides into the melt and subsequent quenching. Four different compositions were tested: by varying the C content between 2 and 6 wt.%, the effect of the primary carbides on the foam microstructure could be studied. The presence of those carbides appears as an important element for the promotion of the pore nucleation and the prevention of pore coalescence. The addition of SiO2 powder in some experiments illustrated the beneficial effect of a nucleating agent to reach a homogeneous distribution of the gas pores.

  • 66.
    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.
    Synthesis and structural characterisation of porous Al-Fe and Al-Ti materials obtainted by hydrogen solubility variation2007Report (Other academic)
  • 67.
    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.
    Uniaxial compression testing of porous Al-Fe and Al-Ti materials synthesized by water vapor dissolution2007Report (Other academic)
  • 68.
    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.

  • 69. Mitchell, A
    et al.
    Freideriksson, Hasse
    KTH, Superseded Departments, Materials Science and Engineering.
    The electroslag remelting of high-nitrogen steels2004In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 39, no 24, p. 7275-7283Article in journal (Refereed)
    Abstract [en]

    Steels containing nitrogen at levels which are at or above the 1 Bar saturation solubility limit in the liquid at the liquidus temperature offer considerable metallurgical property advantages in many respects. For example, when nitrogen is used as a substitute for carbon in stainless grades, the alloys have superior corrosion properties especially in biomedical applications: nitrogen as a strengthening element in tool steels offers advantages in freedom from carbide particles which affect the polishability. Most of the steels grade of interest require electroslag remelting to control segregation without loss of nitrogen and the behaviour of nitrogen during this process is the subject of this work. It is concluded that the required process pressures are closely related to the alloy composition and that to prevent porosity in the product the ESR step must be carried out at an appropriate overpressure of either nitrogen or argon. The addition of nitrogen during ESR is also discussed and it is shown that this is possible only through solid additives.

  • 70.
    Muhmond, Haji Muhammad
    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.
    An Investigation on the Effect of S and Al on the AusteniteGrowth Morphology in Gray Cast Iron, Using Thermal Analysisand Etching Technique2013In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 66, no 2, p. 185-192Article in journal (Refereed)
    Abstract [en]

    The austenite nucleation and growth morphology was investigated through experiments by inoculation with pure Al in a controlled environment using DTA furnace and H.F furnace. The austenite volume fraction and the dendrite growth orientations were affected by the addition of Al to the melt. Thermal analyses were performed to study the effect of sulfur content on austenite volume fraction and growth morphology using DSC. The possibility of austenite nucleation by MnS particles was analyzed. Different sulfur contents in the alloys were resulting in change in the latent heat of solidification and the rate of austenite formation. Austenite volume fraction was measured with four methods, colour etching, DSC thermal analysis, lever rule, and using LH calculated by Thermo-Calc data base, and a comparison was made among them.

  • 71.
    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.
    Effect of the cooling rate on the graphite nodule count and size distribution in nodular cast iron2018In: 11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Trans Tech Publications, 2018, Vol. 925, p. 45-53Conference paper (Refereed)
    Abstract [en]

    The graphite nodule count, size distribution and homogenization of the nodules distribution are the factors which are of more significance for the properties of the material. By just increasing the inoculants or Mg will not help to get rid of problems like the un-even size distribution and or increasing the nodule count. The cooling conditions of the melt prior to solidification and during solidification can control these two parameters to a large extent. In this research, it is more emphasized on the nucleation sequence of MgO particles and on the cooling rates. The nucleation of MgO at different temperatures and at different cooling rates was found to have a great influence on the nodule size distribution and the homogenization of the microstructure. A mathematical model was derived to relate the Mg concentration in the liquid to the cooling rate, prior to solidification. The MgO particles count was calculated as a function of cooling rate. It was found that at higher cooling rates, MgO can be nucleated in multi steps during cooling process, which can increase the nodule count tremendously.

  • 72.
    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.

  • 73.
    Muhmond, Haji Muhammad
    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.
    Graphite growth control in nodular cast iron2014Manuscript (preprint) (Other academic)
  • 74.
    Muhmond, Haji Muhammad
    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.
    Graphite growth morphologies in cast iron2014In: Solidification and Gravity VI, Trans Tech Publications Inc., 2014, p. 458-463Conference paper (Refereed)
    Abstract [en]

    Graphite growth morphology was studied by using InLense detector on FEG-SEM after performing ion etching on the samples. Star like and circumferential growth mechanism of graphite was observed in the graphite nodules. Pure ternary alloy of hypo eutectic and hyper eutectic composition was treated with pure Mg, Ca and Sr, to study the effect of O and S concentration in the melt, on the transition of graphite morphology from nodular to vermicular/compacted and flake graphite. The change in the melt composition between the austenite dendrites due to microsegregation of S, O and inoculants and their possible effects on the transition of graphite morphologies as well as the nucleation of new oxides/sulfides particles is discussed with the help of thermodynamics.

  • 75.
    Muhmond, Haji Muhammad
    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.
    Graphite Growth Morphologies in High Al Cast Iron2014Manuscript (preprint) (Other academic)
  • 76.
    Muhmond, Haji Muhammad
    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.
    Graphite growth morphologies in high Al castiron2015In: Advances in the Science and Engineering of Casting Solidification: An MPMD Symposium Honoring Doru Michael Stefanescu, The Minerals, Metals, and Materials Society, 2015, p. 323-330Conference paper (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, Sr and Ce on graphite morphology was investigated. In the last experiments, the effect of Ca and Ce in the absence of Mg was studied. The samples were analyzed using field emission-scanning electron microscope (FE-SEM) and energy dispersive x-ray spectroscopy (EDX). In alloys with high Al and Si, the formation of chunky graphite is crucial for control. The effects of Al, Si and inoculants were analyzed 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.

  • 77.
    Muhmond, Haji Muhammad
    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.
    Relationship Between Inoculants and the Morphologies of MnS and Graphite in Gray Cast Iron2013In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 44, no 2, p. 283-298Article in journal (Refereed)
    Abstract [en]

    The influence of oxides and sulfides in gray cast iron on the growth morphologies of MnS and on the nucleation of graphite was experimentally investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX) analysis with evidences that shows the possible nucleation sites for graphite nucleation. Thermodynamic studies have been done on the influence of varying sulfur concentrations on the nucleation of MnS in the melt and during solidification. The consumption of dissolved oxygen and sulfur in the melt during the cooling process was analyzed and we explored how this influenced the nucleation process of oxides and sulfides. A sequential nucleation concept of oxides and MnS is proposed in relation to the growth morphology of MnS and graphite with respect to the mechanical properties of cast iron. The nucleation of new oxides and sulfides was analyzed using thermodynamics and compared to our experimental results. Graphite nucleation on substrates other than MnS, such as MoS2 oxides and (Mo,Cr)S, was experimentally analyzed along with the influence of the substrates on graphite nucleation and growth morphology.

  • 78.
    Muhmond, Haji Muhammad
    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.
    Relationship Between the Trace Elements and Graphite Growth Morphologies in Cast Iron2014In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 45, no 13, p. 6187-6199Article in journal (Refereed)
    Abstract [en]

    The graphite morphology transition was studied using various techniques and additives in ultra-pure binary and ternary alloys with hypo- and hypereutectic compositions. Some of the trace elements were observed to stabilize the flake growth morphology of graphite, while others did not. The distance between the graphite basal planes of spheroidal, flake, and undercooled fine graphite was measured and the lattice fringes were studied using high resolution transmission electron microscope, after preparing a thin lamella of graphite using focused ion beam. Latent heat measurement was performed using differential scanning calorimeter on the pure binary alloy with and without sulfur and oxygen additions. The substitution of various elements under study in a monolayer of graphene was analyzed by considering the binding energies of the elements with C and their bonding nature. Simulations were performed using a molecule editor program and visualizer (Avogadro software), which considers various types of interatomic forces to optimize a monolayer of graphene to a minimum energy. The effect of the type of cyclic C-ring structure and energy of the basal plane of graphite with a connection to the addition of trace elements individually in the monolayer of graphene was studied and simulated to understand the resulting bulk graphite growth morphology.

  • 79.
    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.

  • 80.
    Nassar, Hani
    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, Materials Process Science.
    Peritectic Reactions and Transformations in Low-Alloy Steels2010In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 41A, no 11, p. 2776-2783Article in journal (Refereed)
    Abstract [en]

    Differential thermal analysis (DTA) experiments on low-alloy steels with varying C, Si, Cr, and Mo contents indicated an increase in the difference between the liquidus and peritectic temperatures during solidification with the decrease in C and increase in Mo contents. In a number of the quenched samples, massive transformations of ferrite to austenite were observed. Electron microprobe analysis of the diffusion across a massive transformation front, along with the high growth rates estimated, gives strong reason to believe that these growths are uncontrolled by diffusion. As ferrite transforms to austenite during the peritectic reaction, shrinkage in volume occurs, causing elastic straining at the interface separating the two phases. It was shown through thermodynamic analysis of the equilibrium at the triple point that the increase in energy of the two phases due to this strain can result in undercooling below the equilibrium peritectic temperature and decreases in the equilibrium peritectic concentrations.

  • 81.
    Nassar, Hani
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Korojy, Bahman
    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, Materials Processing.
    A study of shell growth irregularities in continuously cast 310S stainless steel2009In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 36, no 7, p. 521-528Article in journal (Refereed)
    Abstract [en]

    Growth irregularities in continuous casting are believed to be associated with crack formation and breakouts. Differential thermal analysis on 310S stainless steel samples indicated primary precipitations of both austenite and ferrite during solidification. In tensile tests on solidifying samples, abrupt shrinkages in volume were detected in the peritectic range of temperatures. Micrographic and microsegregation analysis on samples extracted from a breakout shell revealed high ratios of primary-precipitated austenite in the thick sections of the shell, and high ratios of primary-precipitated ferrite in the thin sections. Alternating precipitations of austenite and ferrite are proposed to occur during solidification. Regions of the shell with high ratios of primary austenite remain in contact with the mould and exhibit high growth rates, whereas regions with high ratios of primary ferrite shrink in volume due to the ferrite to austenite transformation, which results in the formation of air gaps between the shell and the mould and reductions in growth rate.

  • 82.
    Nick, Arash S.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Vynnycky, Michael
    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.
    A Theoretical Analysis of the Interaction Between Pores and Inclusions During the Continuous Casting of Steel2016In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 47, no 6, p. 2985-2999Article in journal (Refereed)
    Abstract [en]

    A mathematical model is derived to predict the trajectories of pores and inclusions that are nucleated in the interdendritic region during the continuous casting of steel. Using basic fluid mechanics and heat transfer, scaling analysis, and asymptotic methods, the model accounts for the possible lateral drift of the pores as a result of the dependence of the surface tension on temperature and sulfur concentration. Moreover, the soluto–thermocapillary drift of such pores prior to final solidification, coupled to the fact that any inclusions present can only have a vertical trajectory, can help interpret recent experimental observations of pore-inclusion clusters in solidified steel castings.

  • 83.
    Nick, Arash Safavi
    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.
    On the Relationship Between Inclusions and Pores, Part I: Precipitation2012In: Transactions of the Indian Institute of Metals, ISSN 0972-2815, Vol. 65, no 6, p. 791-794Article in journal (Refereed)
    Abstract [en]

    Formation mechanism and clustering of TiN-Al2O3 inclusions precipitated during solidification of austenitic stainless steel is analyzed in this paper. Steel sample are taken from a continuously cast bloom. Clustering of inclusions was examined with a hypothesis that inclusions gather inside the pores. Precipitation of the inclusions occurs through segregation in the residual melt in the interdendritic area. Size and mean distance of the inclusion particles are calculated with mass balance. Impact fracture test in cryogenic temperature reveals clusters of inclusions inside pores on the fracture surface. Size and distribution of the inclusions are examined using light optical microscopy and scanning electron microscopy. Inclusion's composition is investigated with energy dispersive X-ray spectroscopy analysis. Differential thermal analysis and differential scanning calorimetry Tests determined the transformation temperatures. Results of the experiments are in good agreement with theoretical analysis.

  • 84.
    Nick, Arash Safavi
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Michael, Vynnycky
    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.
    Pores and clustering of inclusions in the continuous casting of steel: PrecipitationManuscript (preprint) (Other academic)
  • 85.
    Nick, Seyed Arash Safavi
    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.
    On the relationship between inclusions and pores, Part II: Dendritic structure, pressure drop in the liquid and pore precipitation2014In: 6th International Conference on Solidification and Gravity, 2014, Vol. 790-791, p. 302-307Conference paper (Refereed)
    Abstract [en]

    There is a relationship between pores and inclusions. Inclusions and pores are both formed during solidification inside the interdendritic melt. As hypothesis goes, porosity moves to absorb inclusions and form clusters. Focus of this paper is how solidified dendritic structure affects pore precipitation in austenitic stainless steel. Steel sample is a continuously cast bloom. Temperature profile and width of the mushy zone of the strand is modeled according to a constant temperature at the strands surface. Thermal analysis has been performed with differential thermal analysis (DTA) and differential scanning calorimeter (DSC). Primary dendrite arm spacing (PDAS) is measured with light optical microscopy (LOM) and scanning electron microscopy (SEM). PDAS is represented as the weight average of the distance between parallel sets of primary dendrite stems. Pressure field is calculated based on Darcy's law. Pore formation is described through segregation of the gas components and pressure field in the liquid.

  • 86.
    Ranganathan, Sathees
    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.
    Designing of Ellipsoidal high energy Short Arc Lamp Furnace.2009Report (Other academic)
  • 87.
    Ranganathan, Sathees
    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.
    Influence of Cr and Mn on rapidly solidified Fe-Cr-Mo-Mn-Si-C alloy system.2009Report (Other academic)
  • 88.
    Ranganathan, Sathees
    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.
    Influence of melt temperature on Rapid solidification of Al-Y and Al-Si alloy system2009In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 62, no 4-5, p. 515-519Article in journal (Refereed)
    Abstract [en]

    Solidification behavior of Al-Y and Al-Si were investigated for different melt temperatures. Levitation casting technique was used to achieve a cooling rate of around similar to 2000K/s during the experiment. Light optical microscopy (LOM) and Scanning electron microscopy (SEM) were used to analyze the samples. An energy dispersive system (EDS) analysis of SEM was performed on the samples to identify the phases. Plate like structure of Al8Y3 primary phase was observed at low melt temperature with small percentage of peritectic transformation of Al8Y3 and liquid melt into Al9Y2. A pre-dentritic star like crystal of Al3Y was observed in a fine eutectic matrix at very high melt temperature. Amount and number of primary Si crystals formed in a unit area during the solidification increases as the melt temperature increases. It is believed the melt temperature affects the solidification pattern by changing chemical short range order.

  • 89.
    Ranganathan, Sathees
    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.
    Investigation of microstructures of a rapidly cooled Fe-Cr-Mn-Si-Mo-C alloy after different heat treatments.2007In: Proceedings of the 5th Decennial International Conference on Solidification processing, UK, July 2007, 2007, p. 723-726Conference paper (Refereed)
  • 90.
    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.

  • 91.
    Ranganathan, Sathees
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Makaya, Advenit
    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.
    Savage, Steven
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Rapid solidification behavior of Fe-Cr-Mn-Mo-Si-C alloys2007In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 38, no 6, p. 917-926Article in journal (Refereed)
    Abstract [en]

    The rapid solidification behavior of alloys in the Fe-Cr-Mn-Mo-Si-C system was investigated for different compositions and cooling rates. The C content was varied and alloying additions of Mo and B were studied with respect to their effect on the microstructure. The alloys were cast as either melt-spun ribbons or as 1-mm-thick plates after levitation or as rods 2 to 4 mm in diameter by injection into copper molds. A homogeneous single-phase structure was obtained for the alloy of composition 72.8Fe-8Cr-6Mn-5Si-5Mo-3.2C (wt pct), for a sample diameter of 2.85 mm, at a cooling rate of approximate to 1100 K/s. The single-phase structure was identified as a metastable solid solution, exhibiting the characteristics of the e phase. Upon reheating, decomposition of the single-phase structure into fine bainite plates and secondary carbides was observed between 600 degrees C and 700 degrees C. The annealed structure obtained showed high hardness values (> 850 HV).

  • 92.
    Saleem, S
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Basirat, Mehdi
    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.
    RELATIONSHIP BETWEEN MICROSTRUCTURAL EVOLUTION, ORDER-DISORDER TRANSFORMATION AND PLASTIC INHOMOGENETIES DURING DEFORMATION OF BETA BRASS2014In: TMS 2014 SUPPLEMENTAL PROCEEDINGS, JOHN WILEY & SONS INC , 2014, p. 951-957Conference paper (Refereed)
    Abstract [en]

    Second order phase transition in beta brass has been the focus of researchers for many decades. However, the scientific literature about microstructure and texture evolution in beta brass is scarce. This paper deals with the compression tests performed on the samples of beta brass. An extensive experimental study is carried out by different combinations of strains, strain rates and temperatures. Samples are heat treated prior to deformation to see the role of disordering during compression. The microstructural study and energy calculations show the possibility of order/disorder transition in beta brass during deformation. The plastic in-homogeneities in beta brass can explain by second order phase transition during compression. The calculations also show a relationship between transition and the formation of shear bands.

  • 93.
    Saleem, Saud
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Fredriksson, Hasse (Contributor)
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    The influence of peritectic reaction/transformation on crack susceptibility in the continuous casting of steelsIn: Metallurgical and Materials Transactions B, ISSN 1073-5615Article in journal (Other academic)
  • 94.
    Saleem, Saud
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Basirat, Mitra
    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.
    Microstructural Evolution during Deformation of beta BrassManuscript (preprint) (Other academic)
  • 95.
    Saleem, Saud
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Basirat, Mitra
    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.
    Relation between Microstructural Evolution, Order- Disorder Transformation and Plastic Inhomogeneity during Deformation of Brass2013In: Proceeding of the 143st, TMS, San Diego, California; February 2014, 2013Conference paper (Other academic)
  • 96.
    Saleem, Saud
    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.
    The Effect of Superheating and Cooling Rate on Primary Precipitation of Si in Hypereutectic Al-Si Alloys2013In: Light Metals Technology 2013, Trans Tech Publications Inc., 2013, Vol. 765, p. 135-139Conference paper (Refereed)
    Abstract [en]

    The effect of superheating and cooling rate on primary precipitation of Si was studied in hypereutectic Al-Si alloys. Alloys with compositions of 15, 18 and 20 wt% Si were solidified in unidirectional solidification equipment from different temperatures and drawing speeds. The fraction of primary silicon was measured over a certain distance of the sample in the steady state region. Results show a large variation in primary silicon fraction along the sample length and with varying cooling rate. The fraction of primary silicon and primary aluminium around silicon increases with increasing superheat. These fractions decrease with increasing cooling rate and the structure changes to a more refined dendritic-like primary silicon. Different morphologies of Si and their transformation during solidification can be seen over the sample length. An analysis of the quenched solidification front shows the possibility of strong convection ahead of the solidification front. The convection can be caused by density variation in the liquid due to the cluster structure of the melt which changes the microstructure.

  • 97.
    Saleem, Saud
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Vynnycky, Michael
    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.
    Effect of casting parameters on the formation of oscillation marks during continuous castingManuscript (preprint) (Other academic)
    Abstract [en]

    In the present investigation, oscillations marks formed at the surfaces of two different steel grades are studied; this includes metallographic investigation. The characteristics of the marks are examined rigorously, and the analysis is performed serially. The statistical data is compared withanalytical relations and possible reasons for the deviations from the average values are discussed.From the ongoing analysis, it can be seen that the formation of the primary shell is an important parameter which can affect the depth of the depression. Moreover, the results show that theformation of the oscillation marks is a complex phenomenon and that there could be more than one explanation for their formation.

  • 98.
    Saleem, Saud
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Vynnycky, Michael
    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.
    Formation of the tin rich layer and inverse-segregation in phosphor bronzes during continuous casting2015In: Advances in the Science and Engineering of Casting Solidification: An MPMD Symposium Honoring Doru Michael Stefanescu, The Minerals, Metals, and Materials Society, 2015, p. 15-22Conference paper (Refereed)
    Abstract [en]

    Continuous casting of the phosphor bronzes has been investigated experimentally and analyzed with the help of a thermo-mechanical model. The microscopic investigation shows the spread of the tin rich liquid at the chill surface cause by the formation of flow channels underneath the chill surface. Precipitation of the secondary phases has also been observed under some casting conditions. The macro segregation profile along the solidification thickness predicts a strong casting parameter sensitive inverse segregation. The simulation results show high compressive stresses at the surface of the cast during solidification. The flow channels depth and thermal stress coupled with microsegregation calculations shows the possibility of the pressure driven flow of tin rich liquid towards the chill surface during solidification. The experimental observation and calculated results show that the inverse segregation can be homogenized and decreased by controlling the casting parameter that defines the liquid pool depth into the mould.

  • 99.
    Saleem, Saud
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Vynnycky, Michael
    KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory. 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.
    The Influence of Peritectic Reaction/Transformation on Crack Susceptibility in the Continuous Casting of Steels2017In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 48, no 3, p. 1625-1635Article in journal (Refereed)
    Abstract [en]

    The work presented here examines the surface cracks that can form during the continuous casting of near peritectic steels due to the volume changes during the peritectic reaction/transformation. The investigated samples were collected during plant trials from two different steel grades. The role and mode of the peritectic reaction/transformation are found to depend on the composition of the alloy, resulting in different types of surface cracks. The effect of the local variation in the cooling rate on the formation of the different types of cracks present in each steel grade, which can be due, for example, to the formation of oscillation marks, is demonstrated. The enhanced severity of the surface and internal oxidation, both of which depend on the alloy composition and consequent peritectic reaction, is highlighted. Experimental and theoretical studies show that different types of surface cracks can occur in peritectic steels depending upon the alloy composition and cooling rate, both of which define the fraction of the remaining liquid upon completion of the peritectic reaction/transformation.

  • 100.
    Saleem, Saud
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Vynnyeky, M.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
    Development of an asymptotics-based numerical model for the formation and evolution of air gaps in the vertical continuous casting of alloys2014In: TMS2014 143rd Annual Meeting & Exhibition: Annual Meeting Supplemental Proceedings, 2014, p. 339-346Conference paper (Refereed)
    Abstract [en]

    The formation of an air gap at the mould-metal interface in vertical continuous easting has long been known to have a detrimental effect on the efficiency of the process, and has therefore! attracted many attempts at mathematical modelling and multi-dimensional numerical simulation. However, a recent approach has used asymptotic techniques to derive a quasi-analytical thermomechanical model that captures the essential coupling characteristics: that the formation of the air gap affects the heat transfer, whilst the heat transfer affects the stresses that lead to the formation and evolution of the air gap. In this contribution, we report on preliminary attempts to develop that model, which was for the casting of pure metals, to describe the casting of alloys.

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