Influence of Tool Geometry on the Quality and Mechanical Properties of FSW Weldment for Al-alloy (7020-T53)

Abstract

In this paper the influence of tool geometry and welding parameters (rotating speed and travel speed) on the quality and mechanical properties by using friction stir welded joints for (7020-T53) aluminum alloy.Three types of tool geometry variables were used ( pin, shoulder and shoulder inclination), internal defect (tunnel) was detected by using X-Ray radiography for all samples which are welded at welding parameters (rotating speed and travel speed), perfect tool geometry that gives defect free was by increasing pin diameter with threaded ,increasing shoulder diameter and shoulder inclination (2o) for safety purpose radiography test was also performed to examine defect free of weldments (increasing tool dimensions and pin threaded gives increasing stir and heat input).The effect of welding parameters (rotation and travel speed) using tool geometry that gives defect free were investigated using different mechanical tests including (tensile, bending and microhardness). Macro and microstructure change during (FSW) process were studied and different welding zones were investigated using optical microscope. Based on the friction stir welding experiments conducted in this study the result show that aluminum alloy (7020-T53) can be welded using FSW process, the optimum welding parameters 1400rpm rotational tool speed and 40mm/min travel speed which give the maximum welding efficiency (83%), increasing rotational speed the microhardness increases in weld zone due to decreasing the grain size.