Effect of chloride concentration on the corrosion-fatigue crack behavior of an age-hardenable martensitic stainless steel

Crack growth rate and S-N fatigue testing of Custom 465-H950 was performed in 0.0006-3 M NaCl with different levels of pre-exposure. Custom 465-H950 exhibited a strong corrosion resistance to various NaCl-based exposures. Concurrent exposure and loading did not result in corrosion damage sufficiently severe to drive crack formation away from microstructure features (TiC particles). The total fatigue life of precorroded specimens (pit depth ≈40 μm, surface diameter ≈175 μm) increased 4-9 fold as [Cl−] decreased from 3.0 M to 0.0006 M. Detailed analysis demonstrated that the varying [Cl−] most strongly influenced the initiation life, with secondary contributions from the long- and short-crack propagation regimes.