モリブデイト含有塩酸溶液中におけるType 304ステンレス鋼の応力腐食割れ

抄録

Stress corrosion cracking (SCC) of austenitic stainless steel type 304 has been investigated as functions of nominal stress, molybdate concentration and test temperature in 0.82 kmol/m³ HCl solution by using a constant load method. It is found that the steady state elongation rate in the SCC-dominated region becomes a useful parameter both for predicting time to failure and for the assessment of SCC susceptibility irrespective of the above factors. On the basis of the criterion for SCC assessment, the critical test temperature and critical molybdate concentration are estimated under a constant nominal stress of 388MPa. No pitting corrosion takes place over the whole molybdate concentrations used, which is different from the case of chromate addition. The difference of the role between chromate and molybdate is discussed in terms of ion selective property, the potency of film formation and so on.