On 2018-08-08 14:48:54
Vacuum heat treatment in machinery industry
1. When titanium alloy is treated in vacuum furnace, nitrogen should not be used as cooling gas, because titanium and nitrogen react at high temperature to form golden titanium nitride.
2. The movable connection part of the vacuum furnace is all sealed with O-ring, and this part is cooled by water.
3. When the workpiece is quenched in vacuum, vacuum quenching oil shall be used, which has low saturated vapor pressure.
4. The maintenance of the vacuum furnace shall be in the state of vacuum or pure nitrogen filling to avoid air absorption and moisture absorption when not in use.
5. The pressure rise rate of domestic vacuum furnace shall not be greater than 1.33pa/h, and the standard of some foreign enterprises is 0.67pa/h.
6. Vacuum heating is mainly based on radiation, and the distance between workpieces in the furnace should be kept.
7. During the heating process, the workpiece and furnace materials will be deflated to reduce the vacuum.
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 be equipped with quick cooling device. The pressure of cooling water shall be greater than 0.2MPa, and the flow shall be adjustable.
10. Cooling gas: generally, 99.995% pure nitrogen is used for steel, 99.999% nitrogen or argon is used for superalloy and 99.995% argon is used for titanium alloy.
11. Temperature rise: after the workpiece is put in, it can be heated only when it is pre pumped to 6.67pa.