The Effect Of Tool Profiles On Heat Generation And Distribution During Friction Stir Welding Of Aluminium Alloy

Friction stir welding (FSW) is a solid-state joining process that uses a non-consumable tool to join metallic components. Heat is generated by friction between the rotating tool and the workpiece. In this study the effect of process parameters and tool geometry on heat generation during FSW is investigated through analytical and numerical modelling together experimental validation. Equations of tapered and straight tool profiles for triangular, square, pentagonal, hexagonal and octagonal geometries profiles have been derived first. The derived equations were then implemented in a finite element software package to model heat generation and thermal profile during FSW. Experimental validation was carried out using design of experimental (DOE) method for welding 6061-T6 aluminium alloy. The calculated thermal profiles agree with experimental data. It is found that the amount of heat generation increases with increasing number of flats, and taper ratio, and the highest temperature occurs in a straight octagonal tool profile which has 8 flats. The peak temperature increases around 19% by increase the number of probe flats from 3 to 8, and its taper ratio changes from 0.4 to 1. The tensile strength in experimental welded joints was tested to evaluate the effect of tool profile on mechanical properties. The transverse tensile strength increases approximately 33% by changing the tool profile from straight octagonal (SOct) to straight square (SSQ) due to producing defect free joints with symmetric hardness profiles. The tensile strength of SSQ joint is 79% of base metal strength were obtained using rotational speed of 1000 rpm and a welding speed of 200 mm/min.