On 2018-08-08 14:48:54
Vacuum furnace heat treatment skills
Vacuum heat treatment is the inductive technology combining vacuum technology and heat treatment, which means that the whole and part of the heat treatment process are carried out in vacuum. China divides vacuum into low, medium, high and ultra-high vacuum.
Vacuum furnace and medium frequency electric furnace have a good development prospect in the field of hot working. They are used for induction heating of diathermy, rolling, forging, bending, heat treatment (quenching), welding and other processes. So what are the heat treatment skills of vacuum furnace and medium frequency electric furnace?
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 and form golden yellow titanium nitride.
2. The movable connection part of the vacuum furnace is 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 that of some foreign enterprises shall be 0.67pa/h
6. Vacuum heating is mainly based on radiation, and the distance between workpieces in the furnace shall be adhered to.
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.