Abstract
The stress corrosion cracking (SCC) of SUS 304 and SUS 316 austenitic stainless steels at 353K in 0.82kmol·m-3 hydrochloric and sulfuric acid solutions has been investigated as a function of stress by using constant load method, It is found that stress vs. time to failure curve is divided into three regions, stress, SCC and corrosion regions, respectively. In SCC region the logarithm of time to failure shows a linear function of the logarithm of steady state creep rate, which is obtained from corrosion creep curve, both under constant stress irrespective of solution and material and under fixed solution condition regardless of stress. This indicates that the steady state creep rate becomes a parameter for prediction of time to failure. Furthermore, the order of the steady state creep rate at which no fracture occurs within laboratory time scale is estimated to be less than 10-10m/s. It is also found that the ratio of crack induction time to time to failure holds constant (0.57±0.02) independent of stress, solution and material in SCC region. On the basis of the results obtained, it is inferred that the steady state creep rate is subjected to net corrosion current at the crack tip depending upon the combination of three factors (stress, solution and material). Furthermore, a mechanism of SCC is discussed.
