Corrosion fatigue of austenitic stainless steels for nuclear power engineering

Abstract

Significant structural steels for nuclear power engineering are chromium-nickel austenitic stainless steels. The presented paper evaluates the kinetics of the fatigue crack growth of AISI 304L and AISI 316L stainless steels in air and in corrosive environments of 3.5% aqueous NaCl solution after the application of solution annealing, stabilizing annealing, and sensitization annealing. Comparisons were made between the fatigue crack growth rate after each heat treatment regime, and a comparison between the fatigue crack growth rate in both types of steels was made. For individual heat treatment regimes, the possibility of the development of intergranular corrosion was also considered. Evaluations resulted in very favourable corrosion fatigue characteristics of the 316L steel. After application of solution and stabilizing annealing at a comparable Delta K level, the fatigue crack growth rate was about one half compared to 304L steel. After sensitization annealing of 316L steel, compared to stabilizing annealing, the increase of crack growth rate during corrosion fatigue was slightly higher. The obtained results complement the existing standardized data on unconventional characteristics of 304L and 316L austenitic stainless steels.