Effect of Introducing Surface Compressive Stresses on Stress Corrosion Cracking Resistance of High Strength aluminum Alloys

Author:  Al-Rimawi, Mayyada Rahed
Source:  University of Jordan
Doc ID:  1995006
Year of Publication:  1995
Abstract:  
The high strength aluminum alloy 7075-T6 is used widely in aircraft industry. Nevertheless this alloy is susceptible to SCC expeciall in the welded condition. In this investigation, an experimental program to improve the sterss corrosion cracking resistance of 7075-T6 alloy in chloride enviroment by shot peening has been carried out. Shot peening is a multiple impact of particles onto an elastic/plastic target, whixh esults in compressive stresses. Thus retarding the crack formation and preventing stress corrosion cracking of metal parts. It has been proved that tensile stresses induced by shot peening retard SCC. The experimental work was first carried out to select the best chloride enviroment promoting SCC. The SCC susceptibility of the welded specimen was metallurgically studied and was attributed to the metallurgical change induced during welding. Finally the shot peening effect on the SCC resistance of welded 7075-T6 specimens was studied different intensities. It was found that shot peening is suuperior in preventing SCC at some intensities and retarding it at others.