Fundamental issues and industrial applications of friction-stir welding

A wide range of the same and dissimilar metal and alloy systems were fricti on-stir welded in this investigation and their residual microstructures and hardness profiles examined and compared. The friction-stir weld (FSW) zone is characterized by dynamic recrystallization and in some cases, such as t he FSW of silver to 2024 aluminum alloy, there is considerable grain growth of the silver The FSW of age-hardenable systems such as 6061 and 2024 alum inum alloys and a 6061 Al + 20% Al2O3 metal matrix composite, exhibit degra dation of residual hardness land strength) by as much as 45 per cent from t he base metal. However, in the welding of cast 1100 aluminum alloy there wa s no loss in hardness while for the FSW of A339 aluminum alloy + 10% SiC th e weld zone hardness actually increased noticeably from the base metal. For dissimilar systems involving an age-hardenable member or members the hardn ess reduction depended in part on the starting base metal hardness while in the case of pure metals or non-age-hardenable alloys the lowest hardness w as the limiting parameter The FSW of 6061 Al/2024 Al, 2024 Al/Ag, 2024 Al/C u, 6061 Al/Cu, and even aluminum alloy 6061 Al-20% Al2O2/aluminum alloy A33 9-10% SiC illustrates a wide range of industrial joining applications.