Experimental Investigation of Variation in Mechanical and Microstructural Properties Along the Length of Similar AA6063 FSW.

Abstract

        In this paper, 6063-T4 Al-alloy sheets with dimensions (6x90x200) mm were joined via friction stir welding (FSW). Tow sheets were but welded with square mating edges. The rotating welding tool made of tool steel heat-treated to HRC 60. The temperature distribution had been investigated experimentally with constant revolution speed and constant linear speed. A digital reader of twelve channels was used to read and record the temperature with time at each channel as an excel table. Nine K-type thermocouples were positioned along the weld length. The mechanical properties were evaluated (such as tensile strength , microhardness, and microstructure tests) at room temperature in several positions along the length of the joint. The results show that the max. temperature was conducted at the end of the weld to be 375C?. The relationships between the peak temperature and the time, distance from start, microhardness, tensile strength,  and microstructure were discussed. The hardness of the stirred zone was more than the base metal hardness due to refinement of grains by friction stir process.  The strength and hardness of the FSW were as min. at the end of the weld due to increasing in heat input to the joint at this region which lead to grain growth at the microstructure of last region.