Influence of Flat Friction Stir Spot Welding Process Parameters on Quality Characteristics of AA 6082 Weld

In this article Flat FSSW of three sheets of AA6082 was carried out having thickness of 1mm for each plate. The tool with probe and tool without probe were used for welding process. The use of these tools helps in obtaining the sound quality weld free from keyholes and cracks. The process parameters considered are tool rotational speed of 400, 975 and 1550 rpm, dwell time of 4, 6 and 8 s and plunge depth of 2.6, 2.8 and 3.0 mm. Taguchi analysis was used to optimize the parameters of this investigation for obtaining high tensile strength. An orthogonal array, L9 was applied and analysis of variance (ANOVA) was done to explore the importance of process parameters on various response. Various tests were carried out to investigate the mechanical properties of the weld. Optical microscopy out turn in fine distribution of grains in zones i.e. SZ, TMAZ, HAZ and BM. Scanning electron microscopy of weld was done to investigate the shear fracture in various zones i.e. SZ, TMAZ, HAZ, and BM. Scanning electron microscopy of tool is done before and after welding to investigate the change in microstructure, wear and tear of the tool. X-ray diffraction results in compressed residual stress which helps in obtaining the weld free from cracks. Previously Flat FSSW of AA 6061-T6 aluminum alloy was done which results as the weld free from keyholes and Taguchi method was not applied in this welding process for optimizing the process parameters. As the sound quality of weld is obtained with weld free from keyhole defect and cracks it has future application in light weight cars, aerospace.