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.