The Influence of Ultrasonic Impact Peening on the Mechanical Properties of Similar Friction Stir Welded Joints of AA 7075-T73

Abstract

The purpose of this study is to study the ultrasonic peening influence upon the mechanical properties of the welded joints of 3 mm AA 7075-T73. Friction stir welding (FSW) was carried out by using milling machine and cylindrical tool with tapered pin. The used welding parameters were 710 rpm , 35 mm min for rotational and travel speed , respectively .Tensile tests results showed that the welding efficiency was about 60% for welded samples , and this value increased by using one and two lines ultrasonic peening treatment to 74% , and 71% , respectively , this improvement is due to generating compressive stresses along the surface of welded joints. The microhardness of the welded samples showed that there were fluctuations across the welded centerline and minimum hardness occur in the heat affected zone (HAZ).

Keywords

• aluminum alloy
• friction stir welding
• ultrasonic peening
• mechanical properties