Induction heating is different from other heating methods. The heat energy of induction heating is generated directly inside the heated object. This heating characteristic determines the change in surface temperature and the temperature distribution along the cross section of the heated body. At the same time, during the induction heating process using high-frequency induction heating power, the heating speed is not a constant due to the influence of changes in the physical properties of the material. When heating by electromagnetic induction, the temperature rises much faster than heating by oil or gas. This high-speed heating plays an extremely important impact on the phase change process. One of these features is the effect on the critical point position of the steel.
When using high-frequency induction heating power for induction heating, the phase transformation process of pearlite into austenite is also the same as other heat treatment phase transformations. A horizontal line or inclined line is recorded on the heating kinetic curve, which is equivalent to the strongest phase transformation. period. The starting point of the transformation and the transformation process can be judged based on the temperature and the time spent in the transformation stage. A horizontal (step) line indicates that pearlite transforms into austenite at a certain degree of superheat. The faster the heating rate, the higher the step temperature. The step on the heating curve is the critical point Ac1. The heating temperature is higher than the critical temperature. Due to the fast heating speed and short heating time, the austenite grains will not grow strongly.
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GS-ZP-1200
