Patent ID: 8322592

Claim:
A preventive maintenance method for stress corrosion cracking of a structure formed by welding austenitic stainless steel members together to form a welded junction, comprising: a repair welding step of removing a defective portion present at the welded junction of the structure, and subjecting a remaining portion to repair welding using a repair welding material, thereby forming a repair portion having a heat affected zone; and an overlay welding step, performed after the repair portion is formed, of overlay-welding an austenitic welding material to a surface of the structure, wherein the overlay welding step welds the austenitic welding material over the welded junction including the repair portion and its heat affected zone, wherein the austenitic welding material is different in composition from the repair welding material and has improved corrosion stress cracking resistance, and wherein the austenitic welding material contains C: 0.01 wt % or less, Si: 0.5 wt % or less, Mn: 0.5 wt % or less, P: 0.005 wt % or less, S: 0.005 wt % or less, Ni: 15 to 40 wt %, Cr: 20 to 30 wt %, N: 0.01 wt % or less, O: 0.01 wt % or less, and the balance of Fe and inevitable impurities, wherein the content of B contained as one of the inevitable impurities in the welding material is 3 wt ppm or less, and the total content of C, P, S, N and O in the welding material is 0.02 wt % or less.