Influence of Pin Profile on the Tool Plunge Stage in Friction Stir Processing of Al-Zn-Mg-Cu Alloy.

Friction stir processing (FSP) is a solid state process for refining the microstructure. Though FSP has shown significant impact in manufacturing industry, a detailed investigation is needed for further development of the process. The current article presented an experimental investigation on tool plunge stage by using different pin profiles such as conical, square, pentagonal and hexagonal. Influence of pin profiles on the temperature distribution around the tool during plunge has been studied. Thermocouples were placed at two different locations around the tool in the workpiece of Al-Zn-Mg-Cu alloy and temperatures were measured simultaneously at both the locations. FSP tools with different pin profiles under same process parameters were used to study the effects of pin profile on the temperature of the workpiece. Temperature profile was found to be asymmetric around the tool. During plunging stage, it was observed that the temperature due to plastic deformation at pin was less than the temperature caused by friction on the workpiece. Compared to other pin profiles, pentagon pin generated more temperature during the plunging. Further, tool shoulder had significant influence on the workpiece temperature compared to tool pin. [ABSTRACT FROM AUTHOR]