Effect of Processing Parameters in Obtaining Consolidated Joints and in the Microstructure in Aluminum-Steel Joints Welded by Friction Stir Welding (FSW)

The successful results presented in the literature about the FSW aluminum-steel joints, ignore the appearance and formation of defects at the joint as reference points for evaluation. It also increases the controversy about the presence of intermetallic compounds of the type FexAly, and the lack of information about its origin. The objective of this study is to determine appropriate parameters for obtaining five defects aluminum-steel joints and their relation to the formation of deleterious phases during the FSW. Consolidated welded joints were obtained and determined the microstructure in aluminum alloy 6063-T5 and AISI SAE 1020 welds joints. It was used a tungsten carbide tool (WC-14Co) at rotation and weld speeds of 300 rpm and 150 mm. min(-1), with tool offset of +0.5, +1.0 and +1.5 mm. The results highlight the importance of heat input in the Al-steel welding surface appearance and penetration depth. The microstructural analysis reveals the formation of seven regions in the weld, highlighting the thermo-mechanically affected zone on the steel, a band of ultra fine grains of ferrite and the absence of intermetallic compounds in the Al-steel interface.