Effect of Process Parameters on Wear Behaviour of Friction Stir Welded Heat-treated Aluminium Alloy AA6063-T6

Abstract

This research investigates the influence of welding process parameters(tool rpm and welding speed)on the mechanical properties (wear behaviour, tensile strength and micro hardness) of friction stir welded (FSWed) butt joints while the base metal utilizes as the control. Butt joints were prepared on a vertical milling machine at different tool rpm (750,1150,1450 and 1750 rpm) and at constant welding speeds (35,45,95 and 124 mm/min) respectively. Wear test were performed on the pin on disc tribometer using 1200 rpm disc rotating speed and a constant applied load of 40KN.The result show sthat wear increases by 27.3 % in total with the increase in tool rotation speed from 750rpm to 1150 rpm at constant welding speed 35 mm/min and decreases by 29.7 % in total with the increase in welding speed  from 35 mm/min to 124mm/min at constant tool rotation speed. Similar results were also observed in other combinations of tool rpm and welding speeds. It indicates that an increase in the tool rotational speed leads to increase inthe wear loss and an increase in the welding speed improves the wear resistance. It is also demonstrating that joint welded with different tool rpm and welding speeds greatly affects the tensile strength and micro hardness matrix due to micro structural modification in terms of grain refinement and dynamic recrystallization during welding. A scanning electron microscope is also used to study the worn surface morphology to show the wear characteristics of butt joints which are welded at the different processes. Due to presence of second phase particle in the stir zone, improved hardness and better tensile strength are achieved. Butt joints processed with low tool rpm and high welding speed may exhibit significant improvement in the wear performance and mechanical properties of aluminium alloy.