One-stage nitriding process; its surface hardness is high, about HV1000~1200, with small deformation, low brittleness, simple process, and convenient operation. However, the process cycle is long, the cost is high, and the nitriding layer is shallow. It is mostly used for shallow nitriding layers, rulers, J Precision, high hardness seamless steel pipe;
Two-stage nitriding process; compared with one-stage nitriding, its surface hardness is slightly intermediate (HV850~1000), the deformation is slightly increased, but the infiltration speed is fast, and it is mostly used for seamless steel pipes with deeper nitriding layers and larger batches. ;
Three-stage nitriding process; the infiltration speed is fast, but the hardness, brittleness, deformation, etc. are worse than isothermal nitriding.
In addition, when the nitriding temperature is 500°C, it has the highest surface hardness. Above this temperature, the hardness of fir will decrease. The reason is that the aggregation of nitrides below 500°C is not significant and the smoke dispersion is large. At the same time, taking into account the relationship between nitriding temperature and hardness, nitriding layer depth, seamless steel pipe deformation and many other factors, the nitriding temperature is usually controlled between 480 and 560°C.
Therefore, everyone must choose the appropriate nitriding treatment method according to the technical requirements and production materials of seamless steel pipes.
