Developing a Finite Element Model for Analysing Dissimilar Friction Stir Welding (FSW) of Al/Mg Alloys

Joining of dissimilar materials have been one of the most significant challenges for many industries like aerospace, automotive, shipping and shipbuilding. Since the invention of friction stir welding (FSW), it assists the joining of different similar and dissimilar materials like aluminium, magnesium, titanium, steel, copper etc. From one side aluminium has a very wide application in different industries because of its high strength and high resistance of the corrosion. On the other hand, magnesium alloys have moderate strength and creep resistance. Therefore, joining of aluminium and magnesium attracts enormous research interests. However, investigating the temperature distribution and the mixing of the material inside the welding zone becomes as a significant challenge for researchers. Additionally, a specific friction law is required, because of the complicated friction behaviour between the tool and materials. In this research, Norton friction law is used to develop a finite element model. Then, the model is employed to investigate the thermal and mechanical behaviour, and the possibility of the void formation during FSW. The results of the study showed that, the temperature has an asymmetrical distribution in a range of 350–412 ºC. The highest temperature is predicted to be around 412 ºC at the aluminum side. This issue happens because the thermal diffusivity of AZ31 alloy is lower than AA 6061, therefore the peak temperature on the magnesium side is observed to be lower. Finally, the results have been compared with the numerical and experimental results of the literature in order to verify and validate the model.