Effect of tilt angle for conical pin tool with a conical shoulder on heat transfer and material flow using numerical simulation in friction stir welding

The weld quality is determined by the produced temperature and material flow along the cross-section of the workpiece. In this investigation, a computational fluid dynamics (CFD) model is employed to numerically simulate the heat transfer and material flow of Aluminum alloy AA6061. A conical pin tool with the conical shoulder (CPCS) at different tool tilt angles is considered for a lap joint. Temperature and velocity contours lines are used to study its gradient at different tool tilt angles. The result indicates that higher temperature is generated on trailing advancing side (AS), a high temperature gradient on leading side, and temperature decreases from top to bottom surface along the workpiece thickness. At transverse plane, temperature contour lines lean more towards the advancing side as tilt angle is increased. For CPCS tool, influence of tilt angle on velocity magnitude is negligible. Material from leading AS and front of the tool is observed to be swept along the retreating side (RS) and deposited at the rear of the tool. It is also observed that when tool tilt angle increases, streamlines tend to become more dispersed. It can be deduced that for CPCS, if the tilt angle of the tool is raised, the peak temperature will likewise increase, but the peak material velocity will remain the same. The outcomes of the current investigation are validated by comparison to previously published data. With the above findings and conclusions in mind, CPCS welders can better understand the impact of tool tilt angle on weld quality.