Certain investigation on the failure of AA7075 aluminum alloy, pure aluminum materials and tools during the process of friction stir welding

Abstract

Failure evaluation for base materials, namely AA7075 aluminum alloy and pure aluminum and tool material have been identified during the process of friction stir welding (FSW). Though the friction stir welding is considered as ideal for joining the nonferrous materials, it is difficult to avoid flaws in all materials particularly while using improper welding parameters. The flaws like insufficient penetration at the bottom of the weld and the pores are easily taken place when the materials are welded at a faster rate or welded with a small application of pressure. The present work aims to investigate the failure of base metal and tool material. Pure Aluminum metal and solution heat treated and artificially aged 7075 aluminum alloy has been friction stir welding and failures are investigated. A failure in the AA7075 alloy base metal is the result of welding with precipitate condition in which no fusion occurs in the base metal by using HSS tool. A failure in the pure Aluminum is due to lack of penetration of the tool and stirring effect. Welding with this condition leads to decrease the hardness and tensile strength. Torsion impact causes the failures in the tool materials.