Improving the Strength of Friction-Stir-Welded Joints of AA1100 Alloy

Abstract

This paper deals with the experimental analysis of Friction Stir Welding (FSW) of AA1100 aluminum alloy joined by means of a square pin tool. During the process, temperature measurement has been done by means of K-type thermocouples and it has been noticed that the temperature in the advancing side (AS) of the weld is about 20-25 °C higher than its retreating side (RS). The ultimate tensile strength (UTS) of the welded specimen is increased by 20% of the parent material due to the uniform dispersion of silicon particles present within the base material. Microstructural observations revealed finely arranged equiaxed grains in the nugget region of the weld. X-ray diffraction results showed the formation of alumina (Al2O3) in the weld nugget due to high heat generation and exposure to atmospheric oxygen during welding. Residual stress measurement exhibited a M-shaped distribution. The samples joined at low travel speed and high tool rotational speed showed compressive residual stress in the joint region. Residual stress of the material lying below the tool shoulder is found to be tensile in nature. Also, it has been noticed that the residual stress in the AS is superior in magnitude than the RS of the weld specimen.