Simulation and experimental study on microstructure evolution of 5CrNiMoV steel during multi-directional non-isothermal forging

Abstract

Microstructure evolution during the hot forming shows a significant impact on material’s mechanical properties. To explore the deformation characteristics of 5CrNiMoV steel, numerical simulation and microscopic phase-field simulation of the multi-direction forgings were carried out. The strain distribution at each pass was investigated and the evolution of temperature, effective strain, effective strain rate, and grain size was acquired. The hot forging trials were carried out and three typical regions of forgings were taken to study the microstructure evolution. Detailed microstructure characterizations showed that the constructed parent austenite grain size of the forging in typical regions was slightly larger than the simulation results due to the grain coarsening during the air cooling. There were large amounts of high angle grain boundaries (HAGBs) for the occurrence of complete dynamic recrystallization and many bulging grain boundaries showed that discontinuous dynamic recrystallization (DDRX) could be the governing mechanism of nucleation and growth of dynamic recrystallization (DRX). Besides, the hot deformation texture changed significantly during the non-isothermal forging and the texture component differed remarkably at different regions of the forging. The main hot deformation texture components were Cube {001} and Goss{011}.

Keywords

• microstructure evolution
• prior parent austenite grains
• textures
• non-isothermal forging
• FEM simulations