Investigation of mechanical properties and surface roughness of friction stir welded AA6061-T651

Abstract

Friction stir welding (FSW) of 6-mm-thick plates of AA6061-T651 was carried out using a simple cylindrical pin tool. The impact of welding factors (rotational speed, welding speed) on tensile properties, microhardness, and surface roughness of FSW joints was investigated. Ultimate tensile strength (UTS), yield strength, and % elongation of AA6061-T651 base plate as well as FSW joints were found out using a universal testing machine (UTM). Maximum value of UTS and yield strength were achieved at rotational speed of 1400 rpm and welding speed of 20 mm/min. Minimum surface roughness was reached at rotational speeds of 1400 rpm and welding speed of 20 mm/min. Microstructural evolutions in the friction stir welded (FSWed) joint and microhardness profile were also determined. Maximum hardness of HV 120 was acquired for the stir zone (SZ). Hence, attainment of the maximum tensile strength, microhardness, and minimum surface roughness during FSW is a desired method to improve the service life and suitability of AA6061-T651.