On reinforcing the friction stir weld joints of AA5086-H116 using the plasma spray coatings

Abstract

The fatigue properties of friction stir weld joints of AA5086-H116 alloy, reinforced with Al2O3 particles using the plasma spray coating method, were investigated after single and double weld passes. A relatively uniform distribution of reinforced particles was achieved with superior properties, even higher than that of the parent alloy. The reinforced joints had enhanced hardness as well as joint efficiency, the double pass being superior to the single pass, but at the cost of reduced total elongation. Furthermore, the reinforced double-pass joints exhibited a remarkable ∼ 55%, ∼ 14%, and ∼ 89% increase in fatigue strength compared to the as-weld, the base material, and single-pass joints, respectively. The fractographic examination mainly revealed a defect-free crack initiation mechanism with a few cases of the ones induced by defects. The superior fatigue performance was mainly attributed to the uniform spatial and size distribution of fine Al2O3 particles within the weld nugget zone, thanks to the novel weld reinforcement method used in this study, which provides a promising avenue for improving the fatigue properties of weld joints.