The effect of sensitizing temperature on stress corrosion cracking of type 316 austenitic stainless steel in hydrochloric acid solution

The stress corrosion cracking (SCC) of a commercial austenitic stainless steel type 316 was investigated as a function of sensitizing temperature (750 1300 K) and test temperature (333-373 K) in 0.82 kmol/m(3) hydrochloric acid (HCl) solution by using a constant load method. From the applied stress dependence of three parameters (i(ss): steady state elongation rate, t(ss): time interval of SCC-dominated failure, t(f): time to failure), the relationships between applied stress and the three parameters were divided into three regions that are dominated by either stress, SCC or corrosion. In the SCC-dominated region, the logarithm of i(ss) was a linear function of the logarithm of t(f) irrespective of applied stress and test temperature, although its slope depended upon sensitizing temperature. This result showed that the i(ss) became a useful parameter for prediction of t(f) as well as the case of the solution annealed specimens. Furthermore, at the most severe sensitization with a sensitizing temperature of around 1000 K, the slope of the linear function of log i(ss) vs. log t(f) showed a minimum, the value of t(ss)/t(f) was a maximum and the fracture appearance was an intergranular mode. On the basis of the results obtained, the effect of sensitization on SCC was discussed in comparison to the results for the solution annealed type 316 and a qualitative intergranular SCC (IGSCC) mechanism was inferred, (C) 21002 Elsevier Science Ltd. All rights reserved.