0.82kmol・m^-3塩酸溶液におけるSUS 304及びSUS 316オーステナイトステンレス鋼の応力腐食割れに及ぼす温度の影響

The stress corrosion cracking (SCC) of SUS 304 and SUS 316 austenitic stainless steels in 0.82kmol/m³ hydrochloric acid solution has been investigated as a function of temperature at various constant stresses by using constant load method. The logarithmic relationship between steady state creep rate (ε_ss) and time to failure (t_f) is found to show the linear function under constant stress irrespective of temperature and material (SUS 304 and SUS 316), that's, logε_ss=-logt_f+Const. In addition, it is also fund that the logarithmic relationship between ε_ss and t_f obtained as a function of stress for SUS 304 and SUS 316 shows the linear function under constant environmental condition, logε_ss=-2logt_f+C′. These imply that ε_ss becomes a parameter for prediction of t_f, since ε_ss is determined from corrosion creep curve at a time within 10 to 20% of t_f. The critical temperature (T_cri.), below which no SCC occurs, is estimated by using 1×10^-9m/s of ε_ss as an indicator, <br>T_cri.≈270K for SUS 304<br>T_cri.≈282K for SUS 316<br>On the basis of the results obtained, a mechanism of SCC is qualitatively discussed in terms of crack propagation in induction period and corrosion current at crack tip.