Effect of Silicon Carbide Particles on Mechanical and Metallurgical Properties of Friction Stir Welded Joints of Aluminium 6082 Alloy

Aluminium 6082 as a light weight structural material with specific strength, good damping properties and machine ability, is one of the most attractive material in applications of transportation and mobile electronics for effectively reducing weight. In 1991 a solid state joining process named Friction Stir Welding was developed and this technique has attracted considerable interest from the aerospace and automotive industries, since it is able to produce defect free joints particularly for light metals i.e. magnesium and aluminium alloy. In this investigation an attempt has been made to study the effect of friction stir welding parameters on mechanical and metallurgical properties of Aluminium 6082 alloy. The selected material was welded using combination of single and double pass Friction stir welding at tool rotational speed of 1600 rpm, welding speed (40 mm/min, 60 mm/min and 80 mm/min) and doping Silicon Carbide particles. Doping of Silicon Carbide particles improves the tensile strength and microhardness as compared to base material as received. It has been observed that high microhardness at the rate of two times was achieved by doping SiC particles during Friction Stir Welding.The maximum value of microhardness at the rate of 137 Hv is achieved with double pass friction stir welding. High tensile strength of 300 N/m2 is obtained at the welding speed of 60 mm/min with double pass friction stir welding. The fine and equiaxed grains were obtained due to dynamic recrystallization at the Stir Zone of Friction Stir welded joints. Double pass Friction stir welding causes homogeneous dispersion of SiC particles.It was also observed that excessive heat generation and insufficient flow of plasticized material at higher values of tool rotational speed, leading to formation of defects which ultimately results in failure of weld joints between SZ and TMAZ.