Fretting wear and fatigue behavior of steam turbine blade steel

Addressing the issue of cracking and chipping occurring on the lacing wire of the last stage blade in nuclear power turbines, a study was conducted on the fretting wear and fatigue behavior of the blade steel X12CrNiMoV12-2. The effect of fretting wear on fatigue life was studied by conducting fretting wear and high-cycle fatigue tests on a single sample. The results indicate that the length, angle, and location of cracks initiated within the wear scar vary cause by different fretting operation, thereby resulting different fatigue life. When fretting running in the partial slip condition and mixed condition, more dangerous cracks are generated, making fatigue cracking more likely to occur and the fracture position is always in the fretting wear scar. However, cracks initiated in the gross slip condition are less likely to continue to propagate, and the fatigue behavior is consistent with that of the original sample, even the fracture position is no longer in the fretting wear scar region. Further investigation into the mechanisms of crack initiation and propagation has been conducted, establishing a correlation between crack stress factor K* and fatigue life.