High-Frequency Induction Hardening with Controlled Capacitors-Discharge Pulse-Operation Processes

The paper deals with induction hardening processes with power pulses obtained by means of capacitors-discharge high-frequency generators. The process is characterized by high power densities and heating times of the order of some tens or hundreds of milliseconds, together with cooling rates obtained by self-quenching without the use of auxiliary means. The paper examines the possibility of obtaining the most favourable transient temperature distribution in the workpieces by controlling the shape of the pulses and therefore the variable time rate energy supply. The influence of shape of pulses, and discharge-circuit's electrical parameters on the heating and cooling transients has been analyzed by a thermal model, which also allows to predict the depths of hardening. Measurements from hardening tests carried out on steel samples varying the pulse shapes are given in support of the calculation results.