中频淬火：淬硬层较深(3~5mm)，适用于承受扭曲、压力负荷的零件，如曲轴、大齿轮、磨床主轴等(所用材料为45号钢、40Cr、9Mn2V和球墨 高频的淬火，可以短时间的表层淬硬!晶体组织很细!结构变形小 中频表面应力比高频的要小50HZ叫工频，加热深度5-10 1000-10000HZ叫中频。“高频淬火”与“中频淬火”在原理上是一样的，所以在中频淬火设备的选择上有一定准则。
High-frequency quenching is mostly used for surface quenching of industrial metal parts. It is a metal heat treatment method that generates a certain induced current on the surface of the workpiece, rapidly heats the surface of the part, and then rapidly quenches it.Induction heating equipment, that is, equipment for induction heating of workpieces for surface quenching.
The principle of induction heating: the workpiece is placed in the inductor, and the inductor is generally a hollow copper tube inputting intermediate frequency or high frequency alternating current (1000-300000Hz or higher).
The alternating magnetic field generates an induced current of the same frequency in the workpiece. The distribution of this induced current in the workpiece is uneven, it is strong on the surface, but very weak in the interior, and it is close to 0 in the center. This skin effect is used. , the surface of the workpiece can be heated rapidly, the surface temperature rises to 800-1000 ℃ in a few seconds, and the temperature of the core part is very small.
The intermediate frequency quenching is to place the metal parts in an induction coil, and the induction coil is connected with alternating current to generate an alternating electromagnetic field, and an alternating current is induced in the metal parts.
Due to the skin effect, the current is mainly concentrated on the surface of the metal parts, so the temperature of the surface is the highest, and water spray cooling or other cooling is followed immediately below the induction coil. Since the heating and cooling are mainly concentrated on the surface, the surface modification is obvious, while There is basically no internal modification, and it can have a very special heat treatment effect.