Influence of thermomechanical shrinkage on macrosegregation during solidification of a large-sized high-strength steel ingot

Abstract

Finite element modeling (FEM) validated by experimental work was used to simulate the influence of thermomechanical shrinkage on macrosegregation of alloying elements in a large-sized ingot of high-strength steel. The full algorithms of the filling and solidification process for thermohydraulic and thermomechanic analyses were developed and implemented in the 3D FEM code Thercast®. Material properties were determined by a combination of experimental works, thermodynamic software Thermo-Calc®, a database, and literature source. It was predicted that thermomechanical shrinkage decreased the temperature gradients, advanced the initiation of solidification, and reduced the solidification time. The above changes resulted in less severe segregation along the centerline, in the zone next to the ingot surface, in the upper section of the ingot, and in the hot-top. Thermomechanic model predictions were proved to agree better with experimental results than the thermohydraulic one. The obtained results were interpreted in the framework of the theories on diffusion and solidification of alloyed systems. These findings contribute to a better understanding of the impact of thermomechanical shrinkage in ingot cooling process. They could also be used in industry to improve the quality of large-sized ingot production and the productivity of high value-added steels or other alloys.