Efficient Calculation of Plastic Equivalent Strain and Simulation of Microstructural Evolution in Heavy Plate Rolling Process with Machine Learning

The uneven temperature distribution and deformation in the thickness direction during the hot rolling process of heavy plates lead to uneven microstructures in thicknesses different, seriously affecting product quality. Clarifying the microstructural evolution behavior in the thickness direction of heavy plates is particularly important for product quality control. In the presented work, the temperature field and strain field models under different deformation processes were established using the finite element model (FEM), and the distribution patterns of Plastic Equivalent Strain (PEEQ) at different thicknesses were analyzed. The Plastic Equivalent Strain- Efficient Calculation Model (PEEQ-ECM) is established through symbolic regression algorithm to achieve rapid calculation of PEEQ during the rolling process. The square residual coefficient (R 2 ) of the PEEQ-ECM calculation results reaches 0.9356, and the root mean square error (RMSE) is 1.55. The calculation time is only 8.3% of the time required for FEM`s calculations. On this basis, the microstructural evolution behavior during the rolling process of heavy plates is calculated by combining a microstructural evolution and mechanical property calculation model of hot rolling process. The calculated result shows absolute error of ±2 % for phase fraction and ±2 μm for ferrite grain size.