Static-recrystallization behavior of hot deformation austenite in X70 pipeline steel

The softening behavior of austenite in X70 pipeline steel was investigated on a Gleeble 1500 thermo-mechanical simulator at different deformation parameters by double-pass hot compression testing. The influence of the parameters such as deformation temperature, interval time between passes, strain rate, degree of reduction, and initial austenite grain size on the mechanism of static recrystallization was analyzed. The softening percentage of static recrystallization under different conditions was defined by the 0.2% stress offset method. On the base of experimental data, the value of austenitic static recrystallization activation energy of X70 pipeline steel is 435.3 kJ·mol^-1, and a static recrystallization kinetics model to predict the evolution of softening was developed.