Quality of friction stir welding joints on aluminum 1100 thin plates

Abstract

The Aluminum 1100 series is widely used because of its high corrosion resistance and ductility. Joining aluminum with conventional welding presents challenges due to its poor weldability. Friction Stir Welding (FSW) is a solid-state joining process in which heat is generated by the tool's rotation, with the pin and shoulder rubbing against the material to be welded, stirring it. The FSW process can reduce welding issues when joining aluminum materials. The quality of the joint formed by friction stir welding depends on the welding parameters, as evidenced by numerous prior investigations. However, previous research has been limited to the mechanical strength of welded joints, using destructive testing methods. This allows researchers to examine the quality of welded joints using nondestructive testing. Researchers focus on the quality of friction-stir-welded joints on an AA 1100 thin plate. The tool used has three flat sides, with a tool pin and shoulder diameter ratio of 1:3. The parameters used were variations in the tool's lateral tilt angle, with values of 00, 0.50, and 10. The travel speed was 45 mm/minute with a tool rotation of 1860 rpm. The clamp/fixture was made of S45C, a heat-treated material; the backing plate was mild steel. The AA 1100 material, thicker than 2 mm, undergoes welding. The quality of FSW joints was inspected using nondestructive testing methods, including visual, radiographic, and eddy-current testing. In contrast, mechanical strength was assessed by tensile testing to validate the nondestructive test. The results indicated that tilt angle 00 had no defects, tilt angle 0.50 had tunneling or voids, and tilt angle 10 had defects in the form of material gaps. When the tilt angle was changed to 00, the tensile strength was 85.53 MPa, and the joint efficiency was 78%. When the tilt angle was set to 0.50 and 10, the tensile strength dropped to 61.84 MPa and 71.91 MPa, respectively.