An approach to computational predictions of phase transformations and resultant properties in hot steel rolling

The ability to predict microstructural evolution, phase transformation and resultant mechanical properties is critical to the design of thermomechanical history in multi-pass rolling of bars. This paper presents a computational approach to the modeling of post-rolling phase transformations for the rolled steel bar. This approach uses digitization of the continuous cooling curves to determine the volume fraction of various phases in bar steels and an integrated system for modeling metal flow and microstructural evolution during shape rolling. The integrated system employs a 3D finite element program coupled with microstructure evolution models to predict thermal, mechanical and microstructural changes during rolling in steel bars. The system includes modules for modeling of phase transformation after rolling and prediction of mechanical properties of the rolled product. Such a system has been shown to be a powerful analysis tool that can be used as an inexpensive alternative to the traditional trial and error approach in roll pass design.