Effect of fretting wear regimes on stress corrosion cracking of Alloy 690TT in high-temperature pressurized water

Stress corrosion cracks initiation and propagation of Alloy 690TT under different fretting regimes were investigated. The results indicated that mixed regime had the highest susceptibility to stress corrosion cracking, followed by gross slip regime, and then partial slip regime. Crack initiation depended on the distribution of residual strain induced by fretting regimes. In partial slip and mixed regimes, cracks were mainly initiated at the edge of the wear scar, while in gross slip regime, cracks were randomly distributed on the wear scar. Crack propagation was related to the type of grain boundaries and geometrically necessary dislocation density induced by fretting loading. In partial slip and gross slip regimes, cracks usually tended to propagate intergranularly. While in MR, cracks mainly propagated in a transgranular manner.