Microstructure of the interface in magnesium alloy to aluminium alloy dissimilar joints produced by friction stir welding

Abstract

Friction stir welding (FSW) is a process that was developed by the UK Welding Institute (TWI) in 1991.¹ Because of its status as a solid-phase joining process operating at a temperature below the melting point of the materials being joined, FSW usually generates less residual stress than fusion welding, being also advantageously free from fume, porosity, and solidification cracking. The mechanical properties of welds are equivalent or superior to those of conventional welds and offer a high level of reliability. Other merits of FSW include relatively low equipment costs, low operating costs, and no required training. For this reason, in the decade or so since the principle of FSW was invented, the process has seen a number of practical applications in railway and ship structures as well as for rocket fuel tanks in the aerospace field² and continues to draw considerable attention by the engineering industry worldwide. The foregoing applications, however, all refer to components produced from aluminium alloys.