Experimental and numerical investigations of optimum process window for friction stir welding using flat faced tool pin

摘要

Background/Objectives: In friction stir welding, tools with flat faced pin delivers better weld quality than cylindrical pin. In flat faced pin, improper selection of process parameters often results premature tool failure. Being easily controllable process parameters, proper selection of tool rotation speed with respect to the tool advancing speed not only avoids unwanted weld defects but also enhances tool life. Methods: An integrated experimental and numerical comparative study is made between air and water cooled processes to understand the effects of heat dissipation through the boundaries on temperature distribution. Findings: Optimum range of Pseudo Heat Index (PHI) is achieved by comparing the obtained temperature distribution with material softening temperature. Optimum range of weld speed with respect to the tool rotation speed is derived through the optimum Pseudo heat index. Experimental study on the joint strength validates the proposed optimal process parameter ranges. Novelty : This study outlines a novel approach to develop an optimum process window based on PHI for air and water cooled friction stir welding using tools with flat faced pin.