Iinvestigations on influence of nanoparticles on the properties of swept friction stir spot welded 6061t6 aluminium alloy

Abstract

In recent years, the use of aluminium alloys especially 6xxx series alloys has increased in space frame structures, shipbuilding and inner and outer panels of automotive vehicles to improve the sustainability of these industries. The use of aluminium in vehicles by the automakers has gradually increased, and it has provoked the fascination in alternative joining technologies such as Friction Stir Spot Welding (FSSW). FSSW is a prominent solid-state welding process, mostly used for sheet metal fabrication in automobile manufacturing and aerospace industries. Swept FSSW process is one of the variants among the different types of FSSW. This research work aims to improve the Swept Friction Stir Spot Welding (SFSSW) joint characteristics by applying the novel method of adding the nanoparticles in the weld area of the base metal. The base metal 6061-T6 aluminium alloy and nanoparticles SiC and Al2O3 are used for the investigation. AA6061-T6/SiC and AA6061-T6/Al2O3 SFSSW joints were fabricated using computer numerical control (CNC) machine The guide hole diameter (amount of nanoparticles addition), tool rotational speed and tool traverse speed were considered as process parameters for the design of experiments (DOE) approach for optimizing AA6061-T6/SiC and AA6061-T6/Al2O3 SFSSW joint strength. The lap shear strength, microhardness and wear of the joint were considered as response variables. The percentage of reinforcement is varied by changing the guide hole diameter, which was made on the base plate before welding process as 1.5, 2.0, 2.5 and 3.0 mm. Taguchi L16 orthogonal array with four levels of each control parameter was designed and the experiments were conducted accordingly. newline