オーステナイト系ステンレス鋼の MgCl_2 溶液中における応力腐食割れ挙動

概要

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Stress corrosion cracking behavior of SUS 304 and SUS 316 stainless steels was investigated in terms of concentration and temperature of MgCl_2 solutions with or without dissolved oxygen. The potential-MgCl_2 concentration relation between SCC and pitting corrosion was also studied by constant potential method under the applied stress of 25 kg/mm^2. As dissolved oxygen becomes necessary to cause SCC with decreasing the concentration or the temperature of MgCl_2 solutions, SUS 316 becomes much more resistant to SCC than SUS 304. The crack is often observed originating at the bottom of a pit. The lower limit of MgCl_2 concentration above which cracks develop at 80℃ is about 20% for SUS 304 and about 25% for SUS 316, while the critical SCC potential of SUS 316 is about 50mV more noble than that of SUS 304. Above the lower limit of MgCl_2 concentration, the corrosion mode shifts from SCC to pitting corrosion as the applied potential is raised and the SCC potential range widens with increasing MgCl_2 concentration. Below that, only pitting corrosion occurs.
社団法人日本鉄鋼協会の論文
1976-03-01