Finite-element simulation of moving induction heat treatment

An efficient finite-element procedure with a remesh scheme has been developed for the analysis of the moving induction heat treatment process, wherein relative motion occurs between the coil and the workpiece. In this procedure, the magnetic field is first simulated by using an updated mesh that tracks the moving coil position; the moving heat source within the workpiece material is derived from the magnetic field. The heat equation is then solved to obtain the temperature field created by the heat source. The procedure has been applied to calculate the temperature distributions in 1080 carbon steel cylinders during induction heating. The calculations have been validated by comparison with analytical solutions for the temperature distribution obtained using Green’s function methods. Finally, the temperature, residual stress, and microstructure distributions in quenched 1080 steel cylinders have been obtained using the finite-element procedure. Quenching of the heated cylinders, by both a moving cooling ring and a stationary liquid bath, has been analyzed. The finite-element procedure presented incorporates temperature-dependent material properties, phase transformations occurring in the 1080 steel, the change in magnetic permeability of the 1080 steel at the Curie temperature, and an elastoplastic stress model based on a mixed hardening rule. The simulation results demonstrate that the finite-element procedure could be applied to a variety of moving induction heat treatment problems to determine the residual stress and microstructure distributions in the heat-treated component. It also could be used in the design of process parameters and coils.