The article presents studies of phase transformations taking place in surface layers of nitrided steels as a result of their annealing at 520 °C for 5 and 10 h. Two steel grades were tested, the unalloyed AISI 1085 and the low-alloy AISI 52100. As a result of glow discharge nitriding, at 570 °C/5 h and 540 °C/12 h, respectively, nitrided layers were produced on the steels, consisting of a surface layer of iron nitrides with the structure of ε + γ′ and γ′ and of similar thickness 25. The study showed that during 5 h of annealing at 520 °C, the iron nitride layer already decomposed, which was documented by the analysis of chemical composition and X-ray analysis of the surface layers of steel. Comparative studies on the hardness distribution of surface layers of nitrided as well as nitrided and subsequently annealed AISI 52100 steels showed that after both 5 and 10 h of annealing, the hardness depth profiles were very similar and the effective thickness of the diffusion layer did not change. The results obtained enabled the demonstration that the emission of nitrogen into the atmosphere during annealing of nitrided steels is not accompanied by diffusion of nitrogen into the base layer. This proves that the iron nitride layer is not a source of nitrogen for the diffusion layer during annealing at reduced pressure.

本文介绍了氮化钢表面层在520°C退火5和10 h后发生的相变的研究。测试了两种钢种，即非合金AISI 1085和低合金AISI52100。由于辉光放电渗氮，分别在570°C / 5 h和540°C / 12 h时在钢上产生了渗氮层由氮化铁表面层组成，其结构为ε  +  γ '和γ′，且厚度类似。25.研究表明，在520°C的退火条件下5个小时，氮化铁层已经分解，这已通过化学成分分析和钢表层的X射线分析得到了证明。对渗氮以及渗氮和随后退火的AISI 52100钢表面层的硬度分布进行的比较研究表明，在退火5和10小时后，硬度深度分布非常相似，并且扩散层的有效厚度没有变化。所获得的结果证实了在氮化钢退火过程中向大气中的氮排放并未伴随氮向基层的扩散。