ステンレス鋼の塩化物応力腐食割れ新試験法の開発及び低濃度 NaCl 溶液中 SUS 316 鋼の割れ条件への適用

概要

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Tapered Double Cantilever Beam specimen with artificial crevice has been designed to clarify SCC behaviors of Type 316 stainless steel in dilute NaCl solutions. This specimen has two dimensional characteristics, which mean that both mechanical and chemical parameters are independent of the specimen thickness. The former is stress intensity, K_I and the latter is repassivation potential of crevice, E_R. SCC tests have been conducted potentiostatically in 3, 0.3, and 0.03% NaCl solutions at 80℃ under K_I constant condition. Cracking occurs at the crevice bottom only when the bottom surface is dissolving at potentials more noble than E_R and K_I is over K_<ISCC>, 13∿14kgf/mm^<3/2>. Bulk NaCl concentration has no significant influence on K_<ISCC> and ^.l_<II>, crack growth rate in the region II where ^.l is independent of K_I. Cracking occurs at potentials between -0.23 and -0.18 V(SCE) in 3% NaCl, and between -0.11 and +0.10 V in 0.03% NaCl solution. The lower limit of the potential range for cracking is the potential just more noble than E_R in each solution and the upper corresponds to the potential where the dissolution rate at the crevice bottom is equal to ^.l_<II>.
社団法人日本鉄鋼協会の論文
1980-12-01