Influence of micro-sized Al2O3 particles on microstructure, mechanical, and wear behavior of dissimilar composite joint of AA6061/AA7075 by friction stirprocessing/welding

Abstract

In the present study, the fabrication of dissimilar composite joints of AA6061/AA7075 incorporated with micro-sized Al2O3 particles was carried out using friction stir welding. The impact of the dispersion pattern of different volume fractions of Al2O3 micro-particles (Al2O3mp) under various combinations of tool rotational speed (RS) and traverse speed (TS) on the weld quality was studied. The composite joints were tested for tensile strength, micro-hardness, wear, and microstructural development. The results demonstrated that higher grain refinement due to dynamic recrystallization (DRX) and pinning effect of Al2O3mp considerably improved the weld quality. Higher improvements in the mechanical properties of the composite joints were also observed as the volume fraction of Al2O3mp increased. Consequently, the composite joint processed at RS of 1100 rpm, TS of 40 mm/min with 10% volume fraction of Al2O3mp exhibits the higher tensile strength of 241.35 MPa with joint efficiency of 83.80% and maximum micro-hardness of 157.5 HV. In comparison with base materials, the incorporation of Al2O3mp also improved the wear resistance of the composite joints.