Effects of strain rate on low-cycle fatigue crack growth behavior of 316LN weld metal in high-temperature pressurized water.

Corrosion fatigue (CF) tests of 316LN weld metal were investigated in high-temperature water at different strain rates (0.0004–0.4%/s) under strain amplitude of 0.6%. Relationship between CF life and strain rate was proposed and environmental fatigue correction factor F en was also calculated. It was found that the γ/δ phase boundary was more susceptible to cracking at low strain rates and δ-ferrite worked as a barrier to retard the crack growth at high strain rates. Mechanisms of CF damage involving the effects of strain rate, hydrogen, δ-ferrite and residual strain on crack growth are also discussed. • Quantitative relation between fatigue life of 316LN weld metal and strain rate is purposed. • Effect of δ-ferrite changed with strain rate due to the interaction between localized deformation and environmental damage. • Mechanisms of CF damage involving the effects of hydrogen and residual strain on crack growth are proposed. [ABSTRACT FROM AUTHOR]