Optimal control of induction heating for semi-solid metal forming

Thixoforming technique requires heating the feedstock to a semi-solid state with a uniform temperature distribution, a uniform globular microstructure and an optimum liquid fraction. The skin effect of induction heating results in an exponential heat source (power density) profile within the semi-solid material. In this study, the conjugate gradient method in conjunction with the adjoint method is used to find a heating process to achieve a uniform temperature distribution along the radius of a cylinder in a relatively short time. It is found that a modified CGM may provide a satisfactory heating strategy. The physical and mathematical models take into account the temperature-dependent thermophysical properties. Radiative and convective heat losses and different heating frequencies are also considered.