Analysis of dynamic recrystallization behaviors in resistance heating compressions of heat-resistant alloy by multi-field and multi-scale coupling method

摘要

The deep understanding of the dynamic recrystallization (DRX) behaviors by grain morphology analysis in an electrical-thermal-mechanical coupling process for a heat-resistant alloy involves a multi-field and multi-scale dynamic coupling issue. As for SNCrW austenitic heat-resistant alloy, based on the true stress-strain data the DRX volume fraction evolution kinetics including a modified Avrami type equation, and a modified version of meso-scale cellular automaton (CA) method with Laasraoui-Jonas hardening and recovery models were solved. The multi-field and multi-scale coupling finite element (FE) model was developed by implanting the solved DRX kinetics model and CA model into the electrical-thermal-mechanical multi-field coupling method. Following which, a series of simulations corresponding to different strain rates and temperatures were implemented. The simulated results show that the mean grain size and DRX volume fraction increase with the increase of temperature, and decrease with the increase of strain rate. The microstructural evolution during the whole forming process were illustrated and described numerically. Finally, the simulated grain morphology was validated by metallography observations. The average relative deviation of grain size between experiment and simulation results is limited in 7.47%.