On 2018-08-08 14:48:54
High frequency quenching and medium frequency quenching
What is high frequency quenching
High frequency quenching is mostly used for the surface quenching of industrial metal parts. It is a kind of metal heat treatment method which makes the workpiece surface produce a certain induction current, quickly heat the surface of parts, and then quickly quench.
What is intermediate frequency quenching
Intermediate frequency quenching is put metal parts within an induction coil, induction coil alternating current (ac), to produce alternating electromagnetic field, induction of alternating current in metal parts, because of the skin effect, current mainly concentrated in the surface of the metal, so the temperature on the surface of the highest, followed by water spray cooling or other cooling under the induction coil, due to the heating and cooling are mainly concentrated on the surface, so the surface modification is very obvious, and the internal basic no modification, can have very special heat treatment effect.
The difference between high frequency quenching and intermediate frequency quenching
High frequency quenching and medium frequency quenching belong to a kind of surface heat treatment technology, which is a method of using high frequency (or medium frequency, power frequency) of the induction current to make the steel surface heated quickly, and then immediately cooling.
The working principle of high frequency quenching and medium frequency quenching is the same, is the induction heating principle: that is, the workpiece is put into the inductor, inductor is generally input medium frequency or high frequency alternating current (1000-300000hz or higher) of the hollow copper tube. In alternating magnetic field in the workpiece to produce induced current with frequency, the induced current distribution in the workpiece is not uniform, strong on the surface, and in the internal is very weak, the heart is close to zero, use the skin effect, can make the surface heating quickly, within a few seconds surface temperatures to rise to 800-1000 ℃, and the core temperature is small.
However, during the heating process, the distribution of induced current in the workpiece is not uniform, and the heating effect produced by different current frequencies is also different:
1. High-frequency quenching
The current frequency ranges from 100 to 500 kHz.
Shallow hardened layer (1.5~2mm);
The workpiece is not easy to oxidize;
Good quenching quality;
High production efficiency;
Suitable for working parts under friction conditions, such as generally small gears, shafts (materials used for 45 steel, 40Cr);
2, medium frequency quenching
The current frequency is 500 ~ 10000 Hz;
The hardened layer is deep (3~5mm);
It is suitable for parts that bear distortion and pressure load, such as crankshaft, large gear, grinding machine spindle, etc. (the materials used are 45 steel, 40Cr, 9Mn2V and spheroidal ink;
In short, the biggest difference between high frequency quenching and intermediate frequency quenching is the difference in heating thickness. High frequency quenching can take a short time to harden the surface, the crystal structure is very fine, the structure deformation is small, and the surface stress of intermediate frequency is smaller than that of high frequency.