Thermal Coupling Effect between Coating and Substrate in Induction Brazing Coating

In order to study the coupling effect of coating induced heat and substrate induced heat on substrate temperature field in brazing coating process, a two-dimensional finite element model was established to study the change law of the temperature field between coating and substrate under thermal load during the full cycle of coating preparation, revealing the coupling mechanism of thermal effect of induced heat between coating and substrate on substrate. Taking the induction-remelted titanium-based alloy coating on the surface of titanium alloy as an example, thermal effect of induction thermal coupling between coating and substrate on substrate was studied. At the same time, thermal effect of separate action of induced heat of coating and substrate on substrate was compared. Under combined action of coating induced heat and substrate induced heat, it was found that the melting interface moved from the coating surface and coating/substrate interface to the interior of the coating in both directions. Substrate induced heat had reverse heat input effect on coating melting. Under conditions of the present study, melting of the whole coating finished after 0.38 s when the coating surface started to melt. Comparative research showed that the action of two individual factors was not simple superposition. Under combined action, the maximum temperature of substrate was lower than the sum of individual factor, but the maximum depth and time of phase transformation of substrate were higher than the sum of individual factor. There was a coupling effect between coating induced heat and substrate induced heat. On the basis of substrate induced heat making substrate have a high interface temperature (but lower than the phase transformation temperature), coating with higher temperature could make substrate phase transform by further increasing the maximum temperature of substrate surface.