How to nitriding seamless steel pipe?

According to the basic principle and process characteristics of seamless steel pipe nitriding treatment, its process parameters include nitriding degree, nitriding time and ammonia decomposition rate, etc. The focus here is on the relationship between temperature and decomposition rate.

According to the requirements of the depth and hardness of the nitriding layer, one-stage, two-stage or three-stage treatment can be carried out. At the same time, a reasonable selection should be made according to the material and technical requirements of the seamless steel pipe. It must be comprehensively analyzed and combined with the working conditions. If you do not participate, it must be clear that there is no The heat treatment of seam steel pipe is quenching and tempering treatment.

The three nitriding processes have their own characteristics. Isothermal nitriding (or segmental nitriding) has a high surface hardness of HV1000-1200, small deformation, low brittleness, simple process, and convenient use, but the process cycle is long and the cost is high. , mostly used for shallow nitriding layer, foot, J precision, high hardness seamless steel pipe; Compared with isothermal nitriding, the surface hardness of secondary nitriding is slightly moderate (HV850-1000), the deformation is slightly increased, but the nitriding speed is fast . It is mostly used for seamless steel pipes with deep nitriding layers and large batches. The third stage nitriding speed is fast, but the effect of hardness, brittleness and deformation is worse than that of isothermal nitriding. Therefore, when nitriding treatment is required for seamless steel pipe parts, a comprehensive evaluation can be made according to the technical requirements, working characteristics, production efficiency, manufacturing cost and other aspects of seamless steel pipes to determine the best nitriding process.

It should be noted that for seamless carbon steel pipes and cast iron seamless steel pipes, in order to improve the corrosion resistance of the workpiece: I and nitriding are called corrosion-resistant nitriding. Thin and dense white nitride layer (E phase in 0.015～O.Oomm). J is characterized by high chemical stability. It has different corrosion resistance in humid air, superheated steam, sea water, gas combustion products and weak alkali solution, and the corrosion-resistant nitriding seamless steel pipe piano should be normalized or tempered. Corrosion-resistant nitriding can replace surface treatment methods such as nickel plating, galvanizing, bluing, polishing, and sometimes even alloy steel and stainless steel. The process temperature of the cargo process is about 550-650°C, the time is 1-3 hours, and the ammonia decomposition rate is 45%-70%.

Article source: https://article-realm.com/article/Finance/33019-How-to-nitriding-seamless-steel-pipe.html