1988 年 37 巻 412 号 p. 36-42
An investigation was made on the effect of small amount of Cu on the stress corrosion cracking in welds of Al-Zn-Mg series A7N01 alloys. The environments used were 3.5% NaCl solution, 36g/l CrO3+30g/l K2Cr2O7+3g/l NaCl solution and atomospheric exposure.
The results obtained are as follows:
The weld heat affected zone has higher susceptibility to stress corrosion cracking than the other position. Stress corrosion cracking fracture principally occurs in the weld heat affected zone about 0.5-2mm far from the weld bond.
The addition of Cu increases strongly the resistance to stress corrosion cracking in aged alloys. Especially the addition of Cu increases the initiation time of stress corrosion cracking, but does not improve so effectively the resistance to crack growth rate da/dt corresponding to region II. From the practical point of view, it is necessary to add a small amount of Cu (less than 0.2%) to avoid stress corrosion cracking in aged welds of A7N01 alloy.