Corrosion and Mechanical Aspects of Friction Stir Welded AA6061 Joints: Effects of Different Backing Plates

The mechanical and corrosion characteristics of the friction stir welds (FSW) are defined by the heat generated throughout the process. The backing plate material is crucial for effective temperature control during the FSW process. The detailed examination comprehends how the backing plate material influences the mechanical and corrosion characteristics of AA6061 FSW joints. In this investigation, FSW process variables such as backing plate, the rotation speed of the tool, and traverse speed were varied to obtain a suitable combination of parameters to achieve high corrosion resistance of joints along with satisfactory mechanical properties. An exfoliation corrosion test is carried out to determine the welds' corrosion resistance. An electrical conductivity test was performed to identify the relationship between hardness and electrical conductivity. The results demonstrated that the lowest corrosion rate, 0.8174 mm per year (mm/year), was achieved by a weld produced using an aluminum backing plate at 1200 rpm and 60 mm/min. The weld with the composite backing plate at 1200 rpm, 30 mm/min exhibits the highest corrosion rate of 1.559 mm/year. The maximum ultimate tensile strength (UTS) is found in joints with an aluminum backing plate. Visual observations indicate that post-weld machining improves the corrosion resistance of FSW samples.