How to operate the nitriding furnace
Aug. 30, 2020
How to operate the nitriding furnace
1. heating up
Ammonia gas should be exhausted before heating. The ammonia gas flow rate is more than twice the normal flow rate. For those with strict requirements on deformation, stepped heating can be used, or the heating rate can be less than 50 degrees/h.
2. Exhaust
Generally, the temperature is increased while exhausting, and the temperature is 150-200℃. During the exhausting process, the PH test paper method can be used to check the sealing condition of the furnace tank and pipeline; during the exhausting phase, ammonia gas is continuously introduced to make the furnace pressure reach 200- 400Pa (U-shaped tube filled with oil), the air is not cleared, and the exhaust pipe cannot be ignited. The ammonia decomposition rate can reach 70% during the heating stage. The ammonia volume in the furnace gas is more than 95%, which can reduce the ammonia flow
3. Keep warm
When the temperature reaches the nitriding temperature, adjust the ammonia flow rate so that the ammonia decomposition rate reaches the required range of the process, the furnace pressure is controlled between 200-600Pa, and the ammonia decomposition rate is measured every 15-30 minutes.
4. Cool
After the end of nitriding, close the exhaust valve to reduce the ammonia flow to make the ammonia decomposition rate reach about 70%. Keep the temperature for 2 hours to reduce the brittleness of the workpiece surface; power off and reduce the temperature, maintain the positive pressure in the furnace, and the furnace temperature will drop below 150.
