The effect of microstructure on corrosion behaviour and mechanical properties of friction stir welds of AA2519 and AA2219 Al-alloys

Abstract

The highly weldable AA2219 Al-Cu alloy has been amended as AA2519 Al-Alloy to increase its ballistic resistance. Despite the fact that the mechanical properties of friction stir(FS) welds are improved, corrosion resistance is affected as a result of the diverse microstructural changes which occurs in different zones in the course of welding.Present work is planned to compare and correlate the effect of microstructure on mechanical and corrosion behaviour of AA2219 and AA2519 FS welds. Results of the work shown better corrosion resistance and mechanical properties of AA2519 welds when compared to that of AA2219 welds. The presence of strengthening precipitates Al 2 CuMg, Al 3 Zr and Al 3 Ti provides insulation path for galvanic cell formation between the Al 2 Cu and Al matrix, may be the reason for improved corrosion resistance in AA2519 Al-alloys and it’s welds. Overall it was found that better combination of strength and corrosion resistance was obtained for AA2519 Al-alloy welds. • For the first time a systematic comparison is made between the Microstructure, Mechanical properties and corrosion behaviour of AA2219 and AA2519 alloy friction stir welds. • Effect of precipitates like Al 2 CuMg, Al 3 Zr and Al 3 Ti on mechanical and corrosion properties of AA2519 and AA2219 alloy friction stir welds was studied. • Observed tensile properties and corrosion behaviour was correlated with the microstructure of AA2519 and AA2219 alloy friction stir welds. • Present study is proved that a good combination of tensile strength and corrosion resistance can be achieved in Friction stir welds of AA2519.