High-Cycle Fatigue Properties of Three Kinds of Turbine Rotor Steel

The high-cycle fatigue experiments were carried out for 25Cr2MoVA steel, 25Cr2Mo1VA steel and 40Cr steel, which complied with the manufacture of rotor’s technical specifications. The P-S-N curves of three kinds of steel were fitted based on the unlimited fatigue’s semi-logarithmic model and the morphology of fatigue fracture was analyzed. The results show that the fatigue limits of strength of 25Cr2MoVA steel, 25Cr2Mo1VA steel and 40Cr steel were 465 MPa, 455 MPa and 460 MPa, respectively, when the fatigue cycle was 108 times. With the decrease of stress the fatigue lives of three kinds of steel increased continuously, and the P-S-N curves showed a slow trend of decline, but there was no significant platforms. For 25Cr2MoVA steel, 25Cr2Mo1VA steel and 40Cr steel, the crack initiated from the material surface and propagated radially. The dimple feature was showed in the transient fracture zone for 25Cr2MoVA steel and 25Cr2Mo1VA steel, whose toughness was all better than that of 40Cr steel. The rotor with 25Cr2MoVA steel was safer and more reliable than the other two materials when they suffered subsynchronous oscillation.