Modeling of interdendritic strain and macrosegregation for dendritic solidification processes: Part II. Computation of interdendritic strain and segregation fields in steel ingots

In Part II of this article, the models are applied to analyze the effects of various cooling conditions on the interdendritic-strain history and macrosegregation patterns. The temperature measurements are used to evaluate the heat-transfer coefficient between the ingot surface and the cooling fluid. The model predictions are compared to temperature measurements and carbon-concentration profiles in ingots, where good agreements are obtained. In examining the fluctuated cooling conditions on the interdendritic strain, the results show that the sudden increase in the heat flux is found to increase the compressive strain in the interdendritic-strain region. The drop in the heat flux shows completely opposite behavior, where the tensile strain generates through the same region. The model demonstrates also that interdendritic strain associated with the fluctuated cooling conditions is a major factor in determining macrosegregation quantitatively and qualitatively. The results show that the tensile interdendritic strain results in a positive segregation, whereas the compressive strain yields a negative one. The segregation level depends mainly on the interdendritic-strain history and its rate value. The mechanism of fluctuated-segregation phenomenon as a function of the interdendritic strain is extensively discussed.

[1]  Hasse Fredriksson,et al.  On the formation of pipes and centerline segregates in continuously cast billets , 1994 .

[2]  H. Fredriksson,et al.  Modeling of the peritectic reaction and macro-segregation in casting of low carbon steel , 1996 .

[3]  H. Fredriksson,et al.  Mechanism of peritectic reactions and transformations , 1982 .

[4]  H. Fredriksson,et al.  On the formation of a fluctuated macrosegregation phenomenon in the continuous casting process , 1994 .

[5]  F. Weinberg,et al.  Macrosegregation in a copper alloy directionally cast with exudation of liquid , 1971 .

[6]  J. K. Brimacombe,et al.  Crack formation in the continuous casting of steel , 1977 .

[7]  Wei Shyy,et al.  Modeling of turbulent transport and solidification during continuous ingot casting , 1992 .

[8]  H. Fredriksson,et al.  Solidification of iron-base alloys , 1982 .

[9]  J. Cahoon,et al.  Inverse segregation in directionally solidified Al-Cu-Ti alloys with equiaxed grains , 1985 .

[10]  R. Mehrabian,et al.  Steady state segregation and heat flow in ESR , 1978 .

[11]  S. Kou,et al.  Macrosegregation in Rotated Remelted Ingots , 1978 .

[12]  Christoph Beckermann,et al.  Mathematical Modeling of Transport Phenomena During Alloy Solidification , 1993 .

[13]  Y. Ueshima,et al.  Analysis of solute distribution in dendrites of carbon steel with δ/γ transformation during solidification , 1986 .

[14]  J. Ni,et al.  A volume-averaged two-phase model for transport phenomena during solidification , 1991 .

[15]  S. Kou,et al.  Effect of fluid flow on macrosegregation in axi-symmetric ingots , 1981 .

[16]  A. Mo.  An internal variable description of solidification suitable for macrosegregation modeling , 1994 .

[17]  Christoph Beckermann,et al.  Formation of macrosegregation by multicomponent thermosolutal convection during the solidification of steel , 1995 .

[18]  I. V. Samarasekera,et al.  Centerline porosity in plate castings , 1985 .

[19]  Merton C. Flemings,et al.  Macrosegregation in a multicomponent low alloy steel , 1979 .

[20]  F. Lefaucheux,et al.  Gel growth followed by holographic interferometry case of ADP crystals grown by T-decrease , 1988 .

[21]  T. W. Clyne,et al.  The effect of melt composition on solidification cracking of steel, with particular reference to continuous casting , 1982 .

[22]  M. Rappaz,et al.  Modelling of microstructure formation in solidification processes , 1989 .

[23]  Sumio Kobayashi,et al.  Solute redistribution during solidification with diffusion in solid phase: A theoretical analysis , 1988 .

[24]  J. J. Moore,et al.  Effect of thermal conditions and alloying constituents (Ni, Cr) on macrosegregation in continuously cast high-carbon (0.8 Pct), low-alloy steel , 1989 .

[25]  D. R. Poirier,et al.  Conservation of mass and momentum for the flow of interdendritic liquid during solidification , 1990 .

[26]  J. K. Brimacombe,et al.  Heat flow, gap formation and break-outs in the continuous casting of steel slabs , 1976 .

[27]  R. Latanision,et al.  Grain boundary transport of hydrogen in nickel , 1982 .

[28]  O. Richmond,et al.  Theory of thermal stresses and air-gap formation during the early stages of solidification in a rectangular mold , 1971 .