Investigation into defects occurred in friction stir welded joint of 6061-T6 aluminium alloy

Abstract

Due to the low melting point of aluminium (Al) alloys, it is difficult to join them by fusion welding techniques. After immense research in the field of welding, especially solid state welding processes, it was ascertained that friction stir welding (FSW) processes might be able to eliminate these difficulties. Although the FSW provides a strong bonding, some defects are often reported in the welded joint. These defects are generally responsible for making the joint weak. A continuous research is going on to assess the wear phenomena in FS welded joint. In the present work, a case study was done for analyzing various defects occurred in FS-welded Al 6061-T6 alloy. For the purpose, an augmented vertical milling machine was used as a FSW machine. Total six plates of Al-alloy were taken to make three joints. Welding was done through a non-consumable tool made of AISI D2 steel. The tool rotation and travel speed were selected as two different process parameters during welding. After joining the metals, five different major defects, such as, deformed base, flash, blow holes, bulged edges and collapsed pin were observed. A detailed explanation, including both quantitative and qualitative, behind each defects are discussed comprehensively in this work.