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The so-called vacuum heat treatment is a heat treatment method in which the workpiece is heated to the required temperature in 10-1 ~ 10-2 PA vacuum medium, and then cooled in different media at different cooling rates. Vacuum heat treatment is known as efficient, energy-saving and pollution-free clean heat treatment in contemporary heat treatment field.

Vacuum heat-treated parts have a series of advantages, such as no oxidation, no decarburization, degassing and degreasing, good surface quality, small deformation, high comprehensive mechanical properties, good reliability (good repeatability and stable life). Therefore, vacuum heat treatment is widely valued and widely used at home and abroad. The popularity of vacuum heat treatment is regarded as an important indicator to measure the level of heat treatment technology in a country. Vacuum heat treatment technology is the hot spot of heat treatment process development in recent 40 years, and it is also an important field of advanced manufacturing technology.

Since the vacuum thermal system is so important, I'd like to tell you some points that should be paid attention to in the heat treatment of vacuum pump

1. Nitrogen should not be used as cooling gas when vacuum pump is used to dispose titanium alloy. Because titanium and nitrogen react at high temperature, golden titanium nitride is formed.

2. The movable connection part of vacuum pump adopts O-type rubber ring sealing connection, and this part is cooled by water.

3. Vacuum pump workpiece in vacuum quenching, should use vacuum quenching oil, this oil has low saturated vapor pressure.

4. The vacuum furnace should be kept in vacuum or filled with pure nitrogen to prevent air suction and moisture absorption when not in use.

5. The pressure rise rate of domestic vacuum furnace should be no more than 1.33pa/h, and the standard of some foreign enterprises is 0.67pa/h.

6. Vacuum heating is mainly radiation, and workpiece spacing should be maintained in the furnace.

7. In the process of vacuum pump heating, the workpiece and furnace data will be deflated, so that the vacuum degree drops.

8. The heating temperature of vacuum tempering, vacuum annealing, vacuum solution treatment and vacuum aging is generally the same as that of conventional treatment.

9. The vacuum tempering furnace shall have a quick cooling installation. The pressure of cooling water should be greater than 0.2MPa and the flow rate should be adjustable.

10. Cooling gas: 99.995% pure nitrogen is used for steel, 99.999% nitrogen or argon is used for high temperature alloy, and 99.995% argon is used for titanium alloy.

11. After the vacuum pump is put into the workpiece, it can be heated only when the vacuum pump is pre pumped to 6.67pa.