摘要
Macrosegregation in Fe-0.8 wt pct C alloy solidifying with equiaxed morphology was numerically simulated. Based on a two-phase volumetric averaging approach, heat transfer, melt convection, composition distribution, nucleation and grain evolution on the system scale were described. A weak-coupling numerical procedure was designed to solve conservation equations. Simulations were conducted to study the effects of cooling rate and nuclei density on the macrosegregation pattern. The relative infliJence of thermal buoyancy- and solutal buoyancy-induced flows on macrosegregation was identified. Calculated results indicate that a higher cooling rate establishes a more homogeneous composition. More uniform solute distributions are formed with increasing nuclei density. In addition, it is noted that the direction of channel segregates depends on the relative strength of thermal and solutal buoyancy forces.
Macrosegregation in Fe-0.8 wt pct C alloy solidifying with equiaxed morphology was numerically simulated. Based on a two-phase volumetric averaging approach, heat transfer, melt convection, composition distribution, nucleation and grain evolution on the system scale were described. A weak-coupling numerical procedure was designed to solve conservation equations. Simulations were conducted to study the effects of cooling rate and nuclei density on the macrosegregation pattern. The relative infliJence of thermal buoyancy- and solutal buoyancy-induced flows on macrosegregation was identified. Calculated results indicate that a higher cooling rate establishes a more homogeneous composition. More uniform solute distributions are formed with increasing nuclei density. In addition, it is noted that the direction of channel segregates depends on the relative strength of thermal and solutal buoyancy forces.
基金
support from the Innovative Scientific-Research Project of Institute of Metal Research,CAS under grant No.KGCXZ-YW-206
the Post-Doctor Foundation for China undergrant No.20080431162
the Foundation of Harbin University of Science and Technology,China under grant No.20081526
