Technology And Simulation Of The Temperature Field Of High-melting Point Alloys Welded By Friction Stir Welding

In this paper, the objective of works was to design experimentation of welding mild steel Q235A and Ti—6A1—4V alloy by friction stir welds. In experimentation, we can get well mechanical capabilities and micro-structure of the tin-in by change force, rotate speed and jointing velocity. Then, to analyze the samples with the aim of describing the relation among the joining process, the resultant microstructures and ultimately the properties of the welds to demonstrate the feasibility of friction stir welding (FSW) for joining of high-melting point alloy. Microstructures of the defect — free welds of Ti-6Al-4V showed that, the welds region displayed several microstructurally distinct regions. The stir zone (SZ), because of dynamic recrystallization caused by intense deformation and high temperature exceeded β-transus during FSW, exhibited prior β grain and transformed β. The themo-mechanically-affected zone (TMAZ) was constituted of equiaxed a grain by the DRX. For mild steel Q235A, grains of SZ and HAZ were finer than those of base metal. The properties of the welds was improved extremely. If change the technics parameters in a limited range, the effect of the microstructures of the welds is not remarkable.Another important aspect of the work is simulating the temperature range of FSW by using finite element software ANSYS. Adopted a dynamic coordinate system moving with the stir pin to predigest the mathematics model, we transfer the transient-state to pre-steady state. The heat input includes which from friction between the tool and workpiece, and that derived from the deformation of the plastic metal. When setting up the heat transfer model, the heat from deformation of the plastic metal is ignored.To analyze, contrast and validate the results of simulation, it is found that jointing energy lies on the ratio between rotation and velocity. When the ratio is greater, the jointing energy is increased, and the peak temperature is greater. The temperature range of the cross section is consistent with the microstructures of the welds distribution.