What is the process specification of nitriding furnace

What is the process specification of nitriding furnace

1. Nitriding temperature

(1) 500-530℃ is commonly used, which can ensure that the nitride has a large dispersion and the highest hardness

(2) As the nitriding temperature increases, the depth of the nitriding layer increases, but the hardness decreases significantly. When nitriding is greater than 550℃, the highest hardness of most steel types is lower than 1000HV

(3) Using two-stage nitriding method, the temperature of the second stage is often lower than 560℃

2. Nitriding time.

(1) The nitriding layer thickens with the extension of time, the initial growth rate is large, and then gradually slows down, the general infiltration rate is about 0.01mm/h

(2) With the extension of the holding time, the nitrides aggregate and grow, and the hardness decreases. The higher the temperature, the longer the time, the stronger the growth

3. Ammonia decomposition rate

(1) When the decomposition rate is 20-40%, there are many active nitrogen atoms, and the surface of the part can absorb a lot of nitrogen

(2) When the decomposition rate exceeds 60%, the hydrogen content in the atmosphere will be as high as 52%, which will produce denitrification. At this time, not only the number of active nitrogen atoms decreases, but also a large number of hydrogen molecules and nitrogen molecules stagnate near the surface of the part, causing nitrogen Atoms are not easily absorbed by the surface, so that the nitrogen content on the surface of the part is reduced, and the depth of the nitriding layer is also reduced.