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How to deal with the nitriding of steel in CNC machining

Posted by: Chris Na 2021-05-27 Comments Off on How to deal with the nitriding of steel in CNC machining

We need to nitridize the material in the cnc machining process. Nitriding is the process of infiltrating nitrogen atoms into the surface layer of steel. Its purpose is to improve surface hardness and wear resistance, and to improve fatigue strength and corrosion resistance.

At present, the gas nitriding method is widely used and more mature in the process. It uses ammonia gas to decompose active nitrogen atoms when heated, and forms a nitride layer on the surface after being absorbed by the steel, and at the same time diffuses to the center. The decomposition reaction of ammonia is as follows:

2NH3→3H2+2[N]

 

Nitriding is usually carried out using special equipment or pit carburizing furnace. The quenched and tempered parts must be degreasing and purifying before nitriding. After entering the furnace, ammonia gas should be used to remove the air in the furnace.

 

The decomposition of ammonia starts above 200°C. At the same time, because ferrite has a certain ability to dissolve nitrogen, gas nitriding is generally carried out at a temperature not exceeding A1 (about 500-570°C).

After nitriding, the temperature of the furnace is lowered to below 200°C, the ammonia supply is stopped, and the workpiece is released from the furnace.