Influence of cooling conditions on tensile lap shear strength and microstructure of friction stir welded aluminum alloy 5052-H32 and polycarbonate light weight hybrid joint

Abstract

The joining of dissimilar materials, notably polymer and metal, is incredibly demanding due to the differences in the materials' mechanical, chemical, and thermal characteristics. In this present study, the feasibility analysis of dissimilar materials joints of aluminum alloy AA5052-H32 and polycarbonate (PC) was performed utilizing Friction Stir Welding (FSW) in the lap joint taper threaded tool pin profile. Response surface methodology (RSM) was implemented as a statistical design of the experiment tool for working process parameter optimization. Optical and Field emission scanning electron microscopy was employed to characterize the detailed microstructure of friction stir welded hybrid joint of AA5052-H32 alloy and PC. The mechanical and metallurgical findings demonstrate that AA5052-H32 and PC sheets were effectively bonded together utilizing a mix of macro mechanical interlocking and secondary chemical adhesive bonding of the materials, providing a viable relaxation to adhesive bonding or mechanical fastening. The hardness of the polymer in as-received conditions welded normally and in underwater conditions was measured onshore D hardness scale. The joint obtained at a rotational speed 1118 rpm and welding speed 48 mm/min with a 2° tilt angle had the maximum tensile lap shear strength of 14.86 MPa in air-cooled and 12.47 MPa in a water-cooled environment. Additionally, shore D hardness for optimal set of process parameters were 72 and 75 for air-cooled and water-cooled conditions respectively.