Heat treatment tips for vacuum furnace
Vacuum heat treatment, which is a comprehensive technology combining two specialties of vacuum technology and heat treatment, means that all and part of the heat treatment process is carried out under vacuum. China divides vacuum into low, medium, high and ultra-high vacuum.
Vacuum furnace and medium frequency electric furnace have a very good prospect in the field of thermal processing, used for: induction heating of processes such as heat transmission, rolling, forging, bending, heat treatment (quenching), welding, etc. So what are the heat treatment techniques of vacuum furnace and medium frequency electric furnace?
1. Vacuum furnace treatment of titanium alloys, should not use nitrogen as the cooling gas, because titanium and nitrogen react at high temperatures to form golden yellow titanium nitride.
2. Vacuum furnace active connection part all use O-rubber ring seal connection, this part are through water cooling.
3. The workpiece is quenched under vacuum, vacuum quenching oil should be used, this oil has a low saturated vapor pressure.
4. Vacuum furnace maintenance should be in the vacuum or pure nitrogen state, to avoid the usual use of air absorption, moisture absorption.
5. Domestic vacuum furnace pressure rise rate should not be greater than 1.33Pa / h, the standard of some foreign companies for 0.67Pa / h
6. The vacuum heating is mainly by radiation, and the workpiece should keep spacing in the furnace.
7. In the process of heating up, the workpiece and the material inside the furnace will deflate and make the vacuum degree decrease.
8. The heating temperature of vacuum tempering, vacuum annealing, vacuum solution treatment and vacuum aging is generally the same as the heating temperature of conventional treatment.
9. Vacuum tempering furnace should have quick cooling device. The pressure of cooling water should be more than 0.2Mpa, and the flow rate should be adjustable.
10. Cooling gas: steel generally uses 99.995 percent purity of nitrogen, high-temperature alloys use 99.999 percent nitrogen or argon, titanium alloys use 99.995 percent argon.
11. Heating up: After putting in the workpiece, generally pre-pumping to 6.67 Pa before heating up.