Yorimasa Takeda1 and Masahiro Saito1
1Nagasaki Research and Development Center, Mitsubishi Heavy Industries, Ltd., Nagasaki
In order to evaluate the role of hydrogen and anodic dissolution on the stress corrosion cracking of 5%NiCrMoV steels, stress corrosion cracking tests on the specimens with wide range of temper embrittlement were carried out in a boiling 60%Ca(NO3)2 solution, a boiling 40%NaOH solution and a H2S-saturated 0.5%CH3COOH solution (at room temperature). The effect of temper embrittlement and the role of hydrogen on the stress corrosion cracking were discussed in terms of fracture morphology compared with the hydrogen induced cracking in hydrogen gas.
The stress corrosion cracking in the 40%NaOH solution at open circuit potentials and in the H2S-saturated 0.5%CH3COOH solution could be explained by hydrogen, while the stress corrosion cracking in the 60%Ca(NO3)2 solution and in the 40%NaOH solution at -400 mV (vs Ag/AgCl/sat.KCl) was related to anodic dissolution.
stress corrosion cracking, hydrogen embrittlement, low alloy steels, temper embrittlement, nitrate solution, sodium hydroxide, sulfide stress corrosion
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