Multiphase Model for the Prediction of Shrinkage Cavity, Inclusion and Macrosegregation in a 36-Ton Steel Ingot

Mengye Xie,Houfa Shen

doi:10.3389/fmats.2020.577290

Abstract

A five-phase model consisting of a liquid phase, columnar dendrites, equiaxed grains, air, and inclusion (discrete phase) is developed to predict the shrinkage cavity, inclusion distribution and macrosegregation simultaneously during solidification of a 36-ton steel ingot. The air phase is introduced to feed the shrinkage cavity and no mass or species exchange with other phases occurs. The transport and entrapment of inclusions are simulated using a Lagrangian approach. The predicted results agree well with the experimental results. The characteristics of inclusion distribution are better understood. A thin layer of inclusions tends to form close to the mold wall, and more inclusions reside in the last solidified segregation channels. The inclusion is easy to aggregate near the riser neck, and it is dragged by the solidification shrinkage. The influence of the inclusion on macrosegregation is comparatively small, while the solidification shrinkage affects the formation of macrosegregation significantly and makes the simulation result more accurate.

Highlights

Large steel ingots have been widely used in a variety of industries, such as new-generation nuclear power plants, ship building, aerospace equipment and industrial machinery
In order to investigate the influence of solidification shrinkage and inclusion on macrosegregation, four numerical cases are carried out by using the five-phase model or its simplified form with identical thermodynamic and physical properties
It is termed that the “five-phase model” means with the consideration of both solidification shrinkage and inclusion; “four-phase shrinkage model” means with the consideration of solidification shrinkage but no inclusion; “four-phase inclusion model” means with the consideration of inclusion but no shrinkage; “three-phase model” means without the consideration of both solidification shrinkage and inclusion

Summary

Introduction

Large steel ingots have been widely used in a variety of industries, such as new-generation nuclear power plants, ship building, aerospace equipment and industrial machinery. Chen and Shen (2020) proposed a three-phase model of liquid phase, columnar dendrites, and equiaxed grains, to simulate the evolution of macrostructure and macrosegregation in a 36-ton steel ingot.

Results

Conclusion