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Vacuum heat treatment
From;    Author:Stand originally

1. Vacuum maximum pressure enrages Leng Cuihuo technology

Development of technology of Leng Cuihuo of gas of current vacuum maximum pressure is rapidder, appeared in succession negative pressure (1 × of < 105Pa) shed rate air cooling, pressurization high (105 ~ of 1 × 4 × 105Pa) air cooling, high pressure (105 ~ of 5 × 10 × 105Pa) air cooling, superhigh pressure (105 ~ of 10 × 20 × 105Pa) air cooling new, not only raised vacuum to enrage Leng Cuihuo ability substantially, and brightness of surface of the workpiece after quenching is good, be out of shape small, still have the advantage such as efficient, energy-saving, free from contamination.

Vacuum maximum pressure enrages Leng Cuihuo's utility is material to quench with temper, the solid dissolve of stainless steel and special alloy, effectiveness for a given period of time, ionic cementite and carbolic nitrogen in all ooze, and vacuum agglomeration, the refrigeration after drill rod solder and quench.

When with nitrogen of high pressure of 6 × 105Pa refrigeration quenchs, the load that is cooled can be inattentive only model, high-speed steel (W6Mo5Cr4V2) but temper by dipping in water comes fully 70 ~ 100mm, tall alloy heats up mould steel (like 4Cr5MoSiV) can amount to 25 ~ 100mm, tall alloy Leng Zunmo provides steel (like Cr12) can amount to 80 ~ 100mm.

When with nitrogen of high pressure of 10 × 105Pa refrigeration quenchs, be cooled load can be concentrated model, when cooling than 6 × 105Pa, laden density raises % of 4O of ~ of about 30 % .

When the mixture gas refrigeration that uses nitrogen of superhigh pressure of 20 × 105Pa or helium gas and nitrogen quenchs, be cooled load is concentrated can bind together. Its density relatively 80 % ~ rises when nitrogen of 6 × 105Pa is cooling 150 % , can cool the chromium steel of steel of all high-speed steel, tall alloy steel, hot mould that make work and Cr13 % and more alloy oil steel of temper by dipping in water, be like the 9Mn2V steel of larger size.

The cooling power excel of the heater of temper by dipping in water of double room air cooling that has alone cooling chamber is identical the cell furnace of the type. The cooling effect of the double room furnace with cooling nitrogen of 2 × 105Pa and the cell furnace of 4 × 105Pa comparative. But moving cost, maintenance cost is low. As a result of industry of data of our country foundation (material of black lead, molybdenum) with form a complete set yuan parts of an apparatus (electromotor) wait for a level to remain to rise. Increasing maximum pressure of cell of 6 × 105Pa so while vacuum protects quality, pressurization of development double room and burner of temper by dipping in water of high-pressured air cooling accord with the national condition of our country quite.

2. Isotherm of air cooling of vacuum maximum pressure quenchs
The greater work with complex form undertakes from high temperature easy generation is out of shape when fast refrigeration continuously even crackle. Can quench with saline bath isotherm before solve. In burner of temper by dipping in water of air cooling of cell vacuum maximum pressure whether undertake air cooling isotherm quenchs? Graph 1 contain convection to heat to be in be opposite in burner of temper by dipping in water of air cooling of cell high pressure 120mm of × of 320mm of two groups of φ folds the carbolic element of outfit two pieces after structural steel uses different and cooling means to quench to turning a result. Line of the one cento in the graph is after 102O ℃ heats, use tall pure nitrogen to cool continuously below pressure of 6 × 105Pa (wind direction is to go up, below mutual and alternant, 40s switch) result. Another group is the control refrigeration when undertaking 370 ℃ to sample surface, core. From two cento the contrast of the line can see, the time that core temperature passes 50O ℃ (half cold time) only poor make an appointment with 2min. Undertake from the surface temperature arrives at 370 ℃ controlling cooling initial core around, need 27min. This shows, it is feasible that in cell vacuum maximum pressure gas oil burner undertakes isothermal air cooling quenchs.
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