How to carry out heat treatment in nitriding furnace

In order to shorten the nitriding cycle and make the nitriding process not limited by steel grades, two new nitriding processes, soft nitriding and ion nitriding, have been developed in recent years on the basis of the original nitriding process. This is also the reason why the price of nitriding furnace is high and low.

In essence, soft nitriding is low temperature nitrocarburizing, mainly nitriding. When nitrogen atoms of steel penetrate, a small amount of carbon atoms penetrate. Compared with ordinary gas nitriding, the hardness of the nitrided layer is lower and the brittleness is smaller, so it is called soft nitriding.

1. Soft nitriding methods are divided into three categories: gas soft nitriding, liquid soft nitriding and solid soft nitriding. At present, gas soft nitriding is widely used in domestic production. Gas soft nitriding refers to low temperature nitrocarburizing in an atmosphere containing active nitrogen and carbon atoms. Common eutectonizing media include urea, formamide, ammonia and triethanolamine, which undergo thermal decomposition reaction at soft nitriding temperature to produce active nitrogen and carbon atoms. The active nitrogen and carbon atoms are absorbed by the surface of the workpiece, and penetrate into the surface of the workpiece through diffusion, so as to obtain a nitrocarburizing layer dominated by nitrogen.

The gas soft nitriding temperature is usually 560-570 ℃, because the hardness of the nitriding layer is the highest at this temperature. The nitriding time is usually 2-3 hours, because more than 2.5 hours, the nitriding layer depth increases slowly with time.

2. Structure and characteristics of soft nitriding layer of nitriding furnace ε Phase γ` Phase and nitrogenous cementite Fe3 (C, N), the secondary layer is the diffusion layer, which is mainly composed of γ` Phase harmony ε Phase composition.