The existence of angular and hard AlN inclusions would seriously deteriorate the service life of high-nitrogen stainless bearing steels (HNSBSs). In this work, the formation mechanism of AlN inclusion in HNSBSs under as-cast, annealing and austenitizing states was systematically investigated by microstructure observation and thermodynamic, kinetic analyses. The results showed that the concentration product of Al and N could exceed the critical solubility of AlN inclusion at liquidus temperature with the Al content higher than 0.050 wt pct, which led to the formation of AlN inclusions about 1 to 5 μm (equivalent diameter) in liquid steel. Based on the ‘Clyne-Kurz’ model, AlN inclusion could form at the solidifying front due to the enrichment of N in the residual liquid steel with the Al content higher than 0.030 wt pct. Besides, the precipitation of Cr₂N and the extremely low diffusion coefficient of Al in α phase restrained the precipitation of AlN during annealing at 1023 K. However, AlN and AlN-MnS composite inclusions less than 0.6 μm could precipitate during austenitizing at 1323 K with the Al content higher than 0.006 wt pct, which was the critical Al content to avoid AlN formation in HNSBSs after melting, solidification, and heat treatment processes.

角质和硬质AlN夹杂物的存在会严重降低高氮不锈钢轴承钢（HNSBSs）的使用寿命。通过显微组织观察和热力学，动力学分析，系统地研究了铸态，退火和奥氏体化状态下HNSBS中AlN夹杂物的形成机理。结果表明，Al和N的浓度产品可能超过的AlN夹杂物的在液相线温度与Al含量的临界的溶解度比0.050重％，而导致的AlN夹杂物的生成约1至5更高μm（等效直径）在液态钢中。基于“ Clyne-Kurz”模型，由于残留铝含量大于0.030 wt％的液态钢中的N富集，可能在凝固前沿形成AlN夹杂物。另外，Cr的析出₂ N和在α相Al的极低的扩散系数在1023 K.退火期间抑制AlN的析出但是，AlN和AlN的MnS系夹杂物复合小于0.6 μ M可以在1323奥氏体化过程中沉淀K的Al含量高于0.006 wt％，这是避免HNSBS熔化，固化和热处理后形成AlN的关键Al含量。