Finite element simulation of dynamic recrystallization phenomenon and evaluation of effective factors in friction stir welding in AA-2024 aluminum alloy

In this research, grain size variation and grain distribution and the effect of different factors such as friction, tool rotational speed, linear velocity of the tool, cooling rate, tool geometry and tool penetration depth on the temperature change and grain size during the friction stir welding process of the aluminum alloy Al-2024 sheet with a thickness of 7.8 mm has been investigated. In order to simulate the model of finite element friction stir welding, the Deform 3D software has been used. The tool is a rigid body and a sheet is considered as a formable plastic material. In order to validate, a comparison between simulation data and experimental results was performed. The effect of effective factors on the temperature of the welding and the amount of grain size variation in the cross section of the weld line have been discussed. Among the variables studied, increasing the cooling rate and the linear velocity of the tool reduce the temperature and grain size, and increase the temperature and grain size with increasing other variables. The results show that with the method presented in this paper, precise prediction of the effect of variation of the variables affecting temperature and grain size can be obtained. In the following, these results can be used to determine the optimum conditions for the friction stir welding process