硫酸-塩化ナトリウム溶液中における溶体化オーステナイトステンレス鋼type304の応力腐食割れ : 塩化ナトリウム濃度とクロメイトの影響(<特集>腐食防食)

概要

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Stress corrosion cracking(SCC)of austenitic stainless steel type 304 has been investigated as functions of chromate concentration and test temperature in 0.82 kmol/m^3 H_2SO_4-NaCl solution under a constant applied load by using a constant load method. The linear relationship between the logarithms of time to failure and steady state elongation rate was obtained under a constant applied stress of 388 MPa(or 392 MPa)irrespective of NaCl concentration, chromate concentration and test temperatures as follows : log i_<ss>=-log t_f+C. Under the present experimental conditions, the steady state elongation rate was was found to be a useful parameter both for predicting time to failure and for the assessment of SCC susceptibility. The critical chromate concentration(C^<cri>_<Na2CrO4>)and critical test temperature(T^<cri>)were estimated under a constant nominal stress of 388 MPa and were obtained below, respectively ; log C^<cri>_<Na2CrO4>=0.70・logC_<NaCl>-0.73 10^3/T^<cri>=-0.64logC_<Na2CrO4>+2.11 The results obtained were discussed in terms of ion selectivity of film formed, corrosion current density at crack tips and the length of crack propagation.
社団法人日本材料学会の論文
1999-11-15