Abstract
Friction spot extrusion welding process is successfully performed on dissimilar aluminum alloys of AA2024-T3 and AA6061-T6 under the influence of shoulder features. The joints were analysed by microstructural features and mechanical properties using conventional and advanced tools of visual inspection, optical microscopy, scanning electron microscopy, transmission electron microscopy, electron back scattered diffractions, tensile testing and hardness testing. The results revealed that the joining was obtained by combination of mechanical locking from extruded material of top surface to predrilled bottom surface and diffusion in solid state. The stir zone and plastically deformed metal flow zone were influenced by scroll shoulder and smooth shoulder features. The tensile specimen of scroll shoulder was resulted to higher fracture load of 6381 N whereas the same was 4916 N in case of smooth shoulder. The interface of between plastically deformed metal flow zone and base material of AA6061-T6 can be considered as critical/weakest zone in case of friction spot extrusion. The variations of hardness were observed in stir zone, plastically deformed metal flow zone and thermo-mechanically affected zone in case of friction spot extrusion welding process.
Highlights
The demand of dissimilar aluminum (Al) welds is extensively increasing to meet the requirements of cost reduction, light weight structures and enhanced working efficiency of transport industries
The stir zone and plastically deformed metal flow zone were influenced by scroll shoulder and smooth shoulder features
The extruded material is filled towards the bottom workpiece (i.e. AA6061-T6) in the predrilled cavity that resulted in extruded zone known as plastically deformed metal flow zone (PDZ)
Summary
The demand of dissimilar aluminum (Al) welds is extensively increasing to meet the requirements of cost reduction, light weight structures and enhanced working efficiency of transport industries. Ojo et al [1] mentioned that the spot lap welds of transport industries are conventionally produced by resistance spot welding, which are advanced by frictionbased spot welding processes in recent time. Friction-based welding processes such as friction stir spot welding (FSSW), friction stir clinching (FSC), friction riveting, friction bit joining, friction flow drilling, friction forming and dieless friction stir extrusion joining are developed to produce different components with spot joining, as reported by some researchers [2, 3]. FSSW and friction stir clinching are found promising over resistance spot welding with large number of published articles as reported by Lin et al [4] and Uematsu and et al [5]. Most recent developments are investigated keeping focus on repairing/
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