Finite Element Analysis on Effects of Geometric Constraints on Crack Growth Rate in Nickel-based Alloys

The crack growth rate of stress corrosion cracking (SCC) in nickel-based alloys is greatly affected by the crack tip constraint effect. In order to improve the prediction accuracy of SCC crack growth rate (CGR) at the crack tip of the welded joints in service of nuclear power plants, the micro-mechanic field at the crack tip and the descriptive parameter of SCC crack growth rate under different restraint conditions were studied, the effects of geometric constraints such as specimen thickness and crack length on the crack growth rate were also analyzed. The results show that the SCC crack growth rate of thicker specimens is greater. The restraint effect on CGR at the crack tip caused by specimen thickness is more obvious with lower load level. However, the restraint intensities at crack tips of specimens with different thickness tend to be uniform with higher load level. In view of these two different constraints, the restraint effect on CGR caused by specimen thickness is greater than that caused by crack length.