Effect of processing parameters on microhardness and microstructure of a double-sided dissimilar friction stir welded aa6082-t6 and aa7075-t6 aluminum alloy

Abstract

In this paper the microstructure and microhardness of a double-side friction stir welding (FSW) of AA6082-t6 and AA7075-t6 dissimilar aluminum alloy were investigated. The Vickers microhardness revealed An irregular profiling in the hardness distribution, as against the conventional 'W'-shape trend – due to the difference in the chemical composition of alloys and the rate of precipitation. The microstructure and the microhardness evolution deviate from the conventional trend. The stereo microscopic view (SM) of the weld nugget shows no onion ring with a long flow arm. The scanning electron microscope (SEM) revealed worm hole defect at the heat affected region of the AA6082-t6 alloy. An excellent bonding was formed while the microhardness profile and microstructure evolution were abnormal. However, little flashes observed at the retreating side was as a result of the pre-heating of the plates during the initial welding process.