Damage assessment of 30Cr1Mo1V rotor steel based on the misorientation parameters during high-temperature fatigue process

Abstract

This article reports the fatigue damage assessment of 30Cr1Mo1V rotor steel using the misorientation parameter method. During the high-temperature fatigue process, the average misorientation parameters such as KAM_ave, GROD_ave, and GND_ave presented an overall increasing tendency. KAM_ave and GND_ave increased smoothly, but GROD_ave displayed a non-monotonic and oscillatory change. The decrease of GROD value in the early fatigue stages could be due to the effect of applied stress on grains, which results in a “constraint” effect and leads to lattice rotation toward a certain direction. Since KAM_ave increased obviously (i.e., 27.85%) in the 0%–60% D_f fatigue stage, while GROD_ave increased the most (i.e., 96.85%) in the 80%–100% D_f stage. Therefore, a mixed parameter assessment method is proposed to assess fatigue damage of 30Cr1MolV steel by combining these two parameters.