THE EFFECT OF POTENTIAL ON STRESS-CORROSION CRACKING OF TYPE-316 AND TYPE-310 AUSTENITIC STAINLESS-STEELS

The stress corrosion cracking (SCC) of type 316 and type 310 austenitic stainless steels has been investigated as a function of applied potential and solution temperature in 0.82 kmol m-3 HCl solution under a constant stress condition. The results of type 316 show that the cracking behavior is different at a potential below and above -90 mV(SHE) in the vicinity of the corrosion potential, -60 mV(SHE). Type 310 exhibits no failure at potentials in the cathodic region. The double logarithmic relation between steady state elongation rate and time to failure becomes a linear function irrespective of potential, solution temperature and the materials, although the slope depends upon the potential region (cathodic and anodic) and solution temperature. This implies that the steady state elongation rate becomes a useful parameter for the prediction time to failure as compared to the potential. On the basis of the results obtained, it is suggested that the cracking of type 316 is caused by hydrogen embrittlement (HE) in the cathodic potential region, while in the anodic potential region that of type 316 and type 310 takes place by SCC subjected to anodic dissolution.