Relevance of microstructure to stress corrosion cracking in aluminum-5% zinc and aluminum-5% copper alloys containing titanium

The importance of microstructure on stress corrosion cracking was assessed from metallog. studies on fractured wire specimens of Al-5 Zn and Al-5% Cu in M NaCl. The addn. of 0.2% Ti to Al-Zn decreased the susceptibility to stress corrosion as a result of improved grain boundary pptn. The addn. of 0.3% Ti to Al-Cu increased the stress corrosion resistance because of general 2nd phase pptn. and chilling effect of Ti. Cold-worked alloys had superior resistance over that of the annealed or aged alloys because of break down of the annealed structure and random distribution of 2nd phase particles