Appliciability of fracture mechanics parameters to stress corrosion crack propagation of SUS 304 stainless steel in boiling MgCl2 solution was investigated in consideration of the specimen size effect and the characteristic environmental effect arising from coating of side surface of the specimen.
The stress corrosion crack propagation rate was nearly proportional to the J integral in the medium to high stress region where fracture surface morphology showed the fan-shaped type in the medium stress region and the mixed intergranular-transgranular type in the high stress region. Therefore, it can be understood that the J integral is a dominant fracture mechanics parameter to stress corrosion crack propagation in the medium to high stress region. It may be expected that the elastic fracture mechanics parameters G and K become dominant parameters to stress corrosion crack propagation in the low stress region where fracture surface morphology showed the brittle-facetted type.
Characteristic nonpropagating stress corrosion crack, caused by incomplete penetration of the corrosive solution into the crack tip, was observed on the coated specimen in the low stress region. There was little effect of the coating on the stress corrosion cracking in the medium stress region.
