EFFECT OF STRAIN AND STRAIN RATE ON CRACK INITIATION OF 316L STEEL IN THE SIMULATED PWR WATER

摘要

Austenitic stainless steels are widely used fornuclear power plants components thanks to their goodmechanical properties at elevated temperatures andexcellent corrosion resistance, especially in light waterreactors. This paper presents the study of the strain rateeffect on environmentally assisted corrosion crackinginitiation in simulated pressurized water reactor (PWR)chemistry. Slow strain rate testing of a non-cold worked316L austenitic steel was performed using two strainrates on tapered specimens with two surface treatments at350 °C in PWR simulated water and in air. Detailedprior- and post-testing characterization of the polishedand ground surfaces including roughness, hardness,residual stresses measurements and microstructuralanalysis was made. Transgranular cleavage-like andintergranular environmentally assisted cracking (EAC)initiation was observed at two plastic strain levels. TheEAC initiation appeared on lower strain level only usingthe slower test rate. The effect of the surface finish on thecracking initiation was described using threshold stressand crack depth. Threshold stresses were evaluated foreach specimen and surface treatment. Surface effect wasnot assessed owing to ambiguous definition of last EACcrack.