Differentiation in the SiC Filler Size Effect in the Mechanical and Tribological Properties of Friction-Spot-Welded AA5083-H116 Alloy

Ceramic reinforced friction stir spot-welding (FSSW) is one of the unique welding techniques used to fabricate spot joints. This study is intended to investigate the effect of reinforcement additive particle size in achieving higher weld strengths. AA5083-H116 aluminum alloy plates were welded with nano- and micro-sized silicon carbide (SiC) particles. Investigations of the weld joints prepared using a tool rotational speed of 1300 rpm, tool plunge rate of 25 mm/min, and dwell time of 10 s revealed that the lap shear tensile strength and hardness of the nano-SiC particles added to aluminum joints were higher than those of the micro-SiC particles added to joints. In particular, the nano-SiC particles provided 29.6% higher strength and 23.3% higher hardness than the unfilled FSSW. The uniformly dispersed fine SiC particles in the processed zone provided more nucleation sites for the re-precipitation of new grains and the precipitates in the aluminum matrix. The X-ray diffraction results confirmed that there was no evidence of a new phase (intermetallic compounds). Reinforcement of SiC particles significantly enhanced the wear characteristics, as well (26.3%). Field emission scanning electron microscopy (FESEM) evidenced the uniform distribution of SiC particles in the weld nugget zone. In addition, the fractography of the samples is presented and discussed.