Modelling of continual induction hardening in quasi-coupled formulation

Purpose - As far as the authors know, no sufficiently complete model of continual induction hardening was developed and solved so far. The paper presents both mathematical model of the process and algorithm of its solution in the quasi-coupled formulation. Design/methodology/approach - Computation of electromagnetic and temperature fields is based on the finite element method, while time variable boundary conditions are determined by means of an original theoretically-empirical procedure. Findings - Substantial are backgrounds for design of the inductor and parameters of the field current as well as parameters of the cooling medium. Research/limitations/implications - The model reached a good level of accuracy validated by suitable experiments. Nevertheless, next work in the field will also have to respect history of the heating before cooling itself (the austenitizing temperature is a function of the velocity of heating). Very important is also appropriate meshing of the investigated region to suppress numerical instabilities appearing during the computation process. Finally, acceleration of numerical schemes is a must, because modelling of one common task (on very fast PCs) takes about 4 h. Practical implications - The results and conclusions may be used for designing devices for continual induction hardening of axisymmetric bodies. Originality/value - Complete mathematical and computer model of the process, original methodology for finding the coefficient of convective heat transfer from the cooled part of the heated workpiece to ambient water spray.