Numerical simulation and technology of electric induction heating for welded joints of rail

After the rail is heated at high temperature by flash welding, the grains of the weld and the heat-affected zone are relatively coarse, and at the same time, when the oxide inclusions remain in the joint during the flash welding process, it is easy to germinate the crack source. The use of induction heating to perform post-weld heat treatment of rail welded joints can refine the grains to achieve the purpose of improving the microstructure and reducing the residual stress, which is conducive to the operation and maintenance of the line. In this paper, a finite element model of induction heating for open-close coil of rail was established, and the transformation process of temperature field and microstructure during induction heating was studied. Based on the finite element simulation, the temperature distribution along the specified path of rail was obtained. The response surface experiment was carried out with temperature uniformity as the response value, and the normalizing process parameters were optimized. The results show that heat transfer to the interior is non-uniform in the process of induction heating. When heating to 45s, the first austenitic transformation will occur in the bottom Angle of the rail. The order of significance of factors affecting the temperature uniformity of rail induction heating is heating power, coil spacing and frequency in descending order. The maximum average relative error between the calculated value and the experimental value is less than 4.95%, which verifies the reliability of the model established in this paper.