Tensile properties and microstructural features of friction stir welded Al 6061 joints fabricated by various dual-pin tool shapes

Abstract

This study investigates the influence of tool shapes on tensile properties and microstructural features at stirred zone (SZ) and heat-affected zone of Al 6061 joints welded through friction stir welding (FSW) technique. Six novel dual-pin FSW tools were designed and fabricated consisting of two eccentric pins with different shapes of circle–circle, triangle–triangle (TT), rectangle–rectangle, and the combined pins of circle–triangle, circle–rectangle, and triangle–rectangle. Quasi-static tests were conducted on the welded joint samples and stress–strain data were collected. Dual-pin welding tools led to microstructural evolution including growth in the plastic flow and enlargement in SZ. Weld joints fabricated by TT and rectangle-triangle (RT) tools possessed the maximum values of tensile strength and ductility.