Application of induction heating surface quenching:
The workpiece is subjected to torsion, bending alternating load, requirements of surface layer is higher than the heart under stress or wear resistance, to puts forward to strengthen the requirements on the workpiece surface, suitable for carbon steel We=0.40 ~ 0.50%.
Two, process
Rapid heating and quenching cooling combined immediately.
By rapid heating to be machined steel surface reach the quenching temperature, ranging from heat to the center that is cooled rapidly, only make the surface hardening of martensite, the center is still not quench the original plastic annealing, good toughness (or normalizing and tempering) organization.
Three, the main method:
Induction heating surface quenching (high frequency, intermediate frequency, frequency), flame heating surface hardening, electric contact heating surface hardening, the electrolyte heating surface hardening, laser surface quenching heating, electron beam surface hardening.
Four, induction heating surface hardening
(a) the basic principle:
The workpiece is placed in the inductor with hollow copper pipe is wound into the inside, pass into the AC middle frequency or high frequency, the formation of induced current with the same frequency in the surface of the workpiece, the parts surface heated rapidly (within a few seconds can be temperature 800 ~ 1000 degrees, the heart is still close to room temperature) immediately after the spray cooling (or immersion quenching), to the workpiece surface layer hardening.
(two) the selection of heating frequency
The frequency of the current commonly used are:
1, the high frequency heating: 100 ~ 500KHZ, 200 ~ 300KHZ is commonly used, electronic tube type high frequency heating, hardened layer depth is 0.5 ~ 2.5mm, suitable for small parts.
2, intermediate frequency heating: current frequency is 500 ~ 10000HZ, 2500 ~ 8000HZ power supply equipment commonly used, is a mechanical type medium frequency heating device or silicon controlled intermediate frequency generator. The hardened layer depth ~ 10mm. Suitable for shaft, larger diameter in high gear etc..
3, the frequency of heating: electric current frequency is 50HZ. Equipment used in mechanical power frequency heating power supply, hardened layer depth of 10 ~ 20mm, surface quenching is suitable for large diameter workpieces.
(three), the application of induction heating surface quenching:
Having compared with ordinary heating quenching:
1, heating speed is very fast, can expand the A transformation temperature range, shorten the time of transformation.
2, the workpiece surface after quenching martensite can be obtained very fine, slightly higher hardness (2 ~ 3HRC). The brittleness of low and high fatigue strength.
3, through the work of the process is not easy to oxidation and decarburization, even some of the workpiece after treatment can be directly assembled using.
4, hardened layer depth, easy control, easy to realize mechanization, automation.
Five, the flame surface quenching
Flame surface quenching is suitable for medium carbon steel 35, 45 steel and the medium carbon alloy structural steel 40Cr and 65Mn, gray cast iron, alloy cast iron. Is the rapid heating workpiece using acetylene oxygen or gas oxygen mixed gas combustion flame spraying. The surface of the workpiece to achieve the quenching temperature, cooling water immediately. The depth of hardened layer is 2 ~ 6mm, otherwise it will cause serious overheating surface of workpiece and deformation and cracking.