Friction Stir Reaction Diffusion Welding of AC4C Cast Aluminium Alloy and AZ31 Magnesium Alloy

摘要

Al alloys and Mg alloys are a promising structural material in vehicle fabrication. In order to achieve combine properties, development of reliable joints is required. A variety of attempts to weld Al and Mg alloys using fusion welding showed that fusion welding was not suitable for joining of Al and Mg alloys because much more intermetallic compounds (IMC) formed in the weld, which was deleterious to the mechanical properties. Friction stir welding (FSW) was expected for joining Al and Mg alloys but reporting results showed that IMC were also formed in the weld and liquation phenomenon possibly occurred. However, whether liquation phenomenon occurred or not is not clear because of the stir behavior of a tool. In this study, lap joint is selected for FSW and the insert depth of a tool (the length of probe is 2.6 mm) is strictly controlled less than the thickness of the upper AC4C Al alloy sheet (3-mm-thick). In this way, the disturbing of the tool stir behavior can be eliminated. The tensile strengths, fraction locations of joints and microstructure evolution are evaluated. Eutectic diffusion reaction was confirmed at the lap interface of Al and Mg.