The aluminum, chromium, vanadium and molybdenum elements in traditional alloy steels are very helpful for nitriding. When these elements come into contact with the nascent nitrogen atoms at the nitriding temperature, they form stable nitrides. In particular, molybdenum is not only a nitride-forming element, but also acts to reduce the brittleness that occurs at the nitriding temperature. Other elements in alloy steels, such as nickel, copper, silicon, manganese, etc., are not very helpful for nitriding characteristics. Generally speaking, if the steel contains one or more nitride-forming elements, the effect after nitriding is relatively good. Among them, aluminum is the strongest nitride element, and the nitriding results of 0.85-1.5% aluminum are the best. For chromium steel containing chromium, if there is enough content, good results can also be obtained. However, carbon steel without alloy is not suitable as nitriding steel because its generated nitriding layer is very brittle and easy to peel off.
Most parts can be nitrided immediately after degreasing using gas degreasing method. Some parts also need to be cleaned with gasoline. However, if the final processing method before nitriding is polishing, grinding, or buffing, a surface layer that hinders nitriding may be produced, resulting in uneven or curved nitriding layers after nitriding. In this case, one of the following two methods should be used to remove the surface layer. The first method is to remove oil with gas before nitriding. Then use aluminum oxide powder to perform abrasive cleaning on the surface. The second method is to perform phosphate coating on the surface.
seamless alloy steel tubing A335
