Characterization of Polypropylene Sheet Friction Stir Spot Welded Joint

Abstract

A study to determine the effect of rotational speed and geometric shape of a tool on the mechanical properties of polypropylene joint using the FSSW technique has been carried out. A polypropylene sheet was cut into pieces with a dimension of 150 x 30 x 5 mm. A medium carbon steel bar was machined to fabricate welding tools. Two types of devices with shoulder angles of 0° and 5° were prepared, while the other parametric geometries were the same. While the friction stir spot welding (FSSW) process has been carried out at variations of rotational speeds of 985, 1660, and 2350 rpm, the other welding process parameters, such as tool plunge rate, dwell time, and delay time, were considered constant. The tensile shear load capacity, macrostructure, hardness, and failure mode of the joint results were then evaluated. The results revealed that using a pin tool with a shoulder angle of 5° achieved a maximum tensile shear load capacity at a rotational speed of 2350 rpm with a result of 2253 N due to its wider nugget area. The load capacity increased with the increase of rotational speed. A pin tool angle of 15° with a shoulder angle of 5° may be suggested for the tool's chosen geometry.