Stress corrosion cracking of austenitic stainless steel Type 316 in acid solutions and intergranular SCC mechanism: effects of anion species (Cl− and SO4−2− and sensitizing temperature

Abstract

This chapter investigates the stress corrosion cracking (SCC) of a commercial austenitic stainless steel type 316 as a function of sensitizing temperature (800–1300 K) in 0.82 kmol/m3 sulfuric acid (H2SO4) and 0.82 kmol/m3 hydrochloric acid (HCI) solutions at 353 K by using a constant load method. The three parameters (lss, steady state elongation rate; tss, transition time; tf, time to failure) are obtained from corrosion elongation curves and are divided into three regions of applied stress, irrespective of sensitizing temperature, and anion species, which are dominated by either stress, SCC, or corrosion. In SCC-dominated region, lss becomes a relevant parameter for prediction of tf, although the slope depends on the sensitizing temperature. The maximum applied stress, the minimum applied, and the value of tss/tf in the SCC-dominated region depend upon sensitizing temperature in both solutions. Specifically, at a sensitizing temperature of ∼950 K the maximum applied stress is smaller in 0.82 kmol/m3 H2SO4 and larger in 0.82 kmol/m3 HCI than that of the solution annealed specimens. In addition, sulfate ions are found to become more aggressive than chloride ions for the SCC susceptibility of the specimens with the most severe sensitization.