抄録
Fatigue crack growth (FCG) in air was investigated for sensitized duplex stainless steels which modeled heat-affected zone by welding. The steel was heat-treated for 20 hours at 600°C and 800°C. In order to clarify the FCG mechanism, stress corrosion cracking (SCC) tests were performed in air and distilled water environments. The FCG rate of the steel aged at 600°C was similar to that of as-received material except under high FCG region where brittle fracture surface could be seen in the ductile one. The FCG rate of the steel aged at 800°C was much higher than those of the others ones. Fracture mechanism of the steel aged at 800°C included static fracture which was characterized by facets with flat plane observed also in the SCC test in distilled water. Based on the FCG and SCC rates and the fracture surface observation, crack growth mechanisms were discussed in detail.
