Fatigue Strength Optimization of Aged X00CrNiMoCoTi13‐7‐3‐8 Maraging Stainless Steel

The microstructures, basic mechanical properties, and high‐cycle fatigue behaviors of aged X00CrNiMoCoTi13‐7‐3‐8 maraging stainless steel with different solution treatments were investigated in the present study. Herein we demonstrated that the blocky retained austenite is a restrictive factor in improving the fatigue strength of aged X00CrNiMoCoTi13‐7‐3‐8 maraging stainless steel with different aging treatments, prompting this study to explore the regulation of fatigue properties by controlling the size of blocky retained austenite. Lower solution temperatures result in a reduction in grain size, martensite block dimensions, and blocky retained austenite, as confirmed by optical microstructure, electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD) analyses. The weakest link microstructure leading to fatigue cracking of specimens with different solution treatments is still the blocky retained austenite, and refining the blocky retained austenite by lowering solution temperature from 1100°C to 1000°C can effectively obtain a significant fatigue strength enhancement from 621 to 713 MPa.