High-Temperature Deformation Characteristics of a SA516GR70 Vessel Steel

Abstract

The single-directional and single-pass compression test were conducted on SA516GR70 vessel steel by a Gleeble-3500 thermal-mechanical simulator with the parameters of 800-1100 oC and 0.01-5 s-1. The influence of deformation temperatures and strain rates on the flow stress and the evolution of dynamic recrystallization of the observed steel were investigated. The results showed that the work hardening, dynamic recovery and dynamic recrystallization softening processes might be occurred successively or simultaneously with the strain increasing. The flow stress-strain curves for the compressed steel can be divided into work hardening stage, transition stage, softening stage and steady-state stage. The dynamic recrystallization occurred in the deformation samples when the observed steel was compressed at above temperatures and strain rates. At a certain deformation temperature, increasing the strain rates was helpful to increase the volume fraction of the dynamic recrystallization and to refine the grains. At a certain strain rate, decreasing the deformation temperatures was helpful to refine and homogenize the macrostructures. The deformation activation energy was 377 kJ/mol and the equation of hot deformation was built by analysing stress-strain curve of SA516GR70 steel.