Quantification of static softening process and its effects on work hardening characteristics of a typical high strength steel during multi-pass deformation

Abstract

Heavy components of 300 M steel are usually manufactured by multi-pass forging. It is necessary to study the flow characteristics of 300 M steel during multi-pass deformation, which helps to regulate the flow behaviors during the actual forging process. In the study, multi-pass compression experiments are conducted on the Gleeble-3500 device to mimic the forging process of 300 M steel. Results show that the deformation parameters and inter-pass holding parameters can affect the work hardening rate significantly. It can be ascribed to coupling effects of dynamic softening and static softening behaviors. A unified static softening kinetics model is established to evaluate the coupling effects of static recovery, static recrystallization, and metadynamic recrystallization on the static softening behaviors. The established static softening kinetics model shows high prediction accuracy with a reliability of 0.99605. Furthermore, a new constitutive model is established to describe the effects of dynamic softening and static softening on the flow stress during multi-pass deformation. The prediction accuracy of the new constitutive model is 0.98897 with a mean absolute error of 4.075%, which demonstrates that the established constitutive model is reliable.

Keywords

• high strength steel
• multi-pass deformation
• static softening
• work hardening
• constitutive model