SUS 304 ステンレス鋼の高温水による応力腐食割れ発生と伝播におよぼす環境側因子の影響
1977 年 41 巻 6 号 p. 596-601
詳細
1977 年 41 巻 6 号 p. 596-601
The effects of environmental factors such as testing temperature, pH and chloride concentration of the testing solution, and the applied stress level of the specimen on the initiation and propagation times of stress corrosion cracking of Type 304 stainless steel in high temperature water were studied.
Stress corrosion tests were carried out in an autoclave specially designed to measure the elongation of specimens, loaded with uni-axial tensile stress and exposed to chloride-containing water in the temperature range of 150 to 325°C.
The results of tests showed that each of the environmental factors mentioned above had a significant effects on the time to initiate cracks. Namely, the initiation time of cracking increased with an increase in pH value, and with a decrease in chloride concentration and applied stress level. The most susceptible temperature was 225°C. Furthermore, it became evident that the cracking process after crack initiation proceeded with a rapid propagation; hence the induction period for crack initiation indicated a large fraction of the fracture time.
On the basis of the results obtained above, it was concluded that the environmental factors have a dominating effect on crack initiation rather than crack propagation.
