Vacuum heat treatment of general knowledge
1. When the vacuum furnace processes titanium alloy, nitrogen is not suitable for cooling gas, because titanium and nitrogen react at high temperature to form golden titanium nitride.
2. All the movable connection parts of the vacuum furnace are sealed with o-type rubber ring, and this part is cooled by water.
3. When the workpiece is quenched under vacuum, vacuum quenching oil should be used, which has a low saturation vapor pressure.
4. The maintenance of the vacuum furnace should be in the state of vacuum or filled with pure nitrogen to avoid inhalation and moisture absorption when not in use at ordinary times.
5. The pressure rise rate of domestic vacuum furnace should not be greater than 1.33pa /h, and the standard of some foreign enterprises is 0.67pa /h
6. Vacuum heating is dominated by radiation, and the workpiece should be spaced in the furnace.
7. During the heating process, the workpiece and the materials in the furnace will deflate, making the vacuum degree drop.
8. The heating temperature of vacuum tempering, vacuum annealing, vacuum solid solution treatment and vacuum aging is generally the same as that of conventional treatment.
9. The vacuum tempering furnace shall have a quick cooling device. The pressure of cooling water should be greater than 0.2mpa, and the flow rate should be adjustable.
10. Cooling gas: generally 99.995 percent pure nitrogen is used in steel, 99.999 percent nitrogen or argon is used in high-temperature alloy, and 99.995 percent argon is used in titanium alloy.
11. Heating: after the workpiece is put in, generally, it can be heated only after pre-pumping to 6.67pa