Microstructure and Mechanical Properties of Friction Stir Welded Joint of an Aluminum Alloy Sheet 6005A-T4

The 6005A-T6 alloy had been widely applied in rail transmit industry due to its combination properties of moderate strength, superior resistance to corrosion, and excellent extrusion plasticity. However, few reports were related to the 6005A-T4 alloy in spite of it also presenting considerable properties. In this work, we introduced the FSW method to investigate the weldability and mechanical properties of a thin plate aluminum 6005A-T4 to evaluate its potential application. Fully recrystallized microstructure was obtained in the nugget zone, characterized by equiaxed grain with a size of 2.2 mu m under current welding parameters. The tensile strength can reach as high as 174 +/- 2 MPa with the absence of beta phase, which is equivalent to 83.8% of that of base metal. The dissolution of beta phase will dramatically reduce the micro-indentation hardness down to as low as 58 HV0.2 and the fine grain, for example 2 mu m in this work, will reversely raise this value up to 64 HV0.2. Our investigation provides some perspectives to understand weldability, mechanical properties of the 6005A-T4 alloy, and develop its further applications in the related field.