EFFECTS OF SHOT PENNING ON MECHANICAL PROPERTIES, MICROSTRUCTURAL EVOLUTION AND RESIDUAL STRESS OF SUBMERGED FRICTION STIR-WELDED AA6061-T6 ALLOY

Abstract

The purpose of this work is to study the effect of shot peening on the mechanical characteristics of welded plates which were performed by Submerged Friction Stir Welding (SFSW) on AA6061-T6 alloy. SFSW was carried out under three cooling mediums like water, brine solution, and coolant oil at the rotational speed of 1200[Formula: see text]rpm and welding speed of 45[Formula: see text]mm/min, respectively. The welded samples from each cooling medium were subjected to a shot peening process. A tensile test was carried out on weld peened and welds unpeened joints. The hardness of the various zones of HAZ, TMAZ, and NZ was also investigated. Optical and scanning electron microscopy was used to examine the microstructures of peened and unpeened joints formed by coolant samples. Shot peening has the potential to enhance the compressive residual stress of friction stir welded joints. According to these findings, shot peening had a greater impact on the mechanical properties of welded samples than unpeened samples, including tensile strength, percentage of elongation, and hardness. The grain size was a little bit smaller than the FSW sample because the surface of the welded samples was subjected to more strain during shot peening.