Experimental and Numerical Analysis of Heat Transfer in Friction Stir Welding

ABSTRACT

Friction stir welding(FSW) process operates at temperatures below the melting point of the material. It produces low-distortion; high quality and low cost welds on aluminum alloys, which are extremely difficult to weld by traditional fusion welding. In this paper, a three-dimensional heat transfer model using finite element software ANSYS is developed and experimentally validated to quantify the thermal history. Based on this model, the effects of welding parameters on temperature distribution are investigated. The heat input is modeled as a moving heat source. Boundary conditions and material properties in thermal modeling of FSW which plays a vital role in the final temperature profile are assumed as a realistic model. Simulation results indicate that maximum temperature in FSW process can be increased with increase in rotational speed and decrease in welding speed. The temperature variation during the welding is also measured to validate the calculated results. The calculated results are in good agreement with the experimental data. The results of heat transfer analysis were correlated with micro hardness and tensile properties of the joint. Correlation of peak temperature across the weld with micro hardness showed that dissolution of strengthening precipitates took place at higher temperature. The tensile test showed that the joint failed corresponding to minimum hardness.

Keywords: Frictions stir welding, Heat transfer, Finite element analysis, Tensile strength.

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