Assessment of Stress–Strain and Thermal State of the Billet during Three- and Four-Roll Screw Rolling and Its Influence on Microstructure Formation

Based on computer simulation of the processes of three- and four-roll screw rolling of steel billets and the calculation of the parameters of the stress–strain and thermal states, an assessment of the microstructure formed in the cross-section during the steady-state stage was conducted. In four-roll rolling, compared to three-roll rolling, it is possible to increase the thickness of the fine-grained surface area with equiaxed grains by 2.4 times while reducing the coarse-grained central area with elongated grains in the rolling direction by 4.7 times. It has been shown that the distribution of accumulated deformation and temperature is more uniform along the length of the billet during four-roll rolling.