Experimental Investigation of Static Softening Behavior of a Cr-Co-Ni-Mo Ultra-high Strength Stainless Steel in Double-Pass Compression

The static softening (SS) behavior of a Cr-Co-Ni-Mo ultra-high strength stainless steel (UHSSS) was characterized in this work via the double-pass compression method. The SS fractions were determined by stress-strain curves at deformation temperature ranging from 950 to 1150 degrees C, inter-pass time ranging from 10 to 300 s, pre-strain ranging from 0.10 to 0.15, strain rate ranging from 0.1 to 5 s-1, and initial austenite grain size ranging from 91 to 220 mu m. The experimental results show that the processing parameters greatly affect the SS fraction. The parent austenite grains were reconstructed by the MTEX toolbox. It shows increasing inter-pass time and deformation temperature can promote SS behavior. The SS fractions are supposed to include contributions both from static recovery and static recrystallization. The kinetics of SS for this UHSSS was established. The predicted results are in good agreement with the experimental results, which is supposed to be benefit for the thermomechanical possessing optimization.