Effects of pin diameter on the tool plunge stage in friction stir welding

چکیده مقاله

In this paper, the plunge stage of friction stir welding process has been investigated. Effect of pin diameter on the temperature distribution in the workpiece and its microstructure has been examined experimentally. By using the tools with different pin diameters tests were done and temperature at four points of workpiece was measured during the tool penetration. The results showed that the diameter of the pin had significant effects on the workpiece temperature. Increasing the diameter of the pin was decreased the final temperature of each point of workpiece because the effective friction surface was decreased. Temperature distribution around the tool was clearly asymmetric and the highest temperature was in the back of the tool at trailing edge. At the end of the plunge stage temperature of each point was almost fixed at constant temperature and the process reached a steady state condition. The microstructure of the samples was similar to each other. In the microstructure studies four areas with different microstructure were observed at the cross section of the workpiece. The size and orientation of the grains were different with others. Extent of the areas was affected by pin diameter. The extent of the stir zone and thermomechanical affected zone were reduced by decreasing the pin diameter

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