Abstract
The fracture mode in stress corrosion cracking of several stress corrosion cracking tests of austenitic stainless steels in boiling MgCl2 solution was fractographically investigated by scanning electron microscopy. The results obtained are as follows: (1) The fracture mode depended on stress corrosion cracking testing method under the same environmental condition. Namely, transgranular fracture was observed in stress corrosion cracking of U-bend tests and WOL tests where KI was below about 37MPa√m, while intergranular fracture was found in the transitional region from transgranular fracture to mechanical ductile fracture in both constant load tests and slow strain rate tests. (2) The effect of alloying elements on the fracture mode was revealed in the intergranular fracture in both constant load tests and slow strain rate tests. P, N and Mo promoted susceptibility to intergranular fracture, while Si acted to prevent susceptibility to intergranular fracture.
