Effect of Friction Stir Welding on Microstructural and Mechanical Properties of Copper Alloy

Abstract

Abstract —This study demonstrates the feasibility of joining the commercial pure copper plates by friction stir welding (FSW). Microstructure, microhardness and tensile properties in terms of the joint efficiency were found 94.03 % compare to as receive base material (BM). The average hardness at the top was higher than bottom. Hardness of weld zone was higher than the base material. Different microstructure zones were revealed by optical microscopy and scanning electron microscopy. The stirred zone (SZ) exhibited primary two phases namely, recrystallized grains and fine precipitates in matrix of copper. Keywords —Welding; FSW; Commercial Copper; Mechanical properties I. I NTRODUCTION RICTION stir welding (FSW) is a new solid state welding process, where the weld is produced by softening, plastic deformation combined with forging action caused by tool rotation of base metal (Fig. 1) [1-3]. Absence of melting of base metal in FSW reduces oxidation, residual stress, solidification related defects. The microstructure of the weld generally shows a central weld nugget with onion ring structure, a thermo-mechanically affected zone (TMAZ) close to the nugget, and a very small heat affected zone (HAZ) [4]. Recently many reports on friction stir welding of various metal system such as aluminium [5-10], magnesium [11-12], mild steel [13], stainless steel [14], and dissimilar systems such as aluminium to stainless steel [15], aluminium to steel [16], aluminium to copper [17], aluminium to magnesium [18], have been published. Preliminary studies on the FSW for copper to copper [19-21] and brass [22-23] have also been reported. Copper and its alloys are widely used in industrial applications due to their excellent electrical and thermal conductivities, good strength, and corrosion and fatigue resistances.