Microstructural Control and Tribological Behavior of High-Nitrogen 316LN Austenitic Stainless Steel

Traditional austenitic stainless steel (ASS) faces challenges in operating safely under low-temperature sliding wear conditions because of its relatively low strength and hardness. To address this issue, this study focused on high-nitrogen 316LN ASSs. Through controlled rolling and annealing, three microstructures were designed: non-recrystallized, heterogeneous, and fully recrystallized microstructures (marked by NG, HS, and CG structures, respectively). The influence of environmental temperature and microstructure on the tribological behavior and wear mechanisms of high-nitrogen 316LN ASSs was investigated. The results demonstrate that the HS structure exhibits the lowest friction coefficient because the reduced number of abrasive particles limits the direct contact between the worn surface and the counterpart, outperforming the NG and CG structures. As the environmental temperature decreases, the wear rates of all the structures decrease, with the lowest wear rate observed at –120 °C. At this temperature, the CG structure exhibits the lowest wear rate—surpassing the NG and HS structures—attributed to its low stacking-fault energy, inducing martensitic transformation and forming a nano/submicron crystalline hardened layer. This layer effectively prevents crack propagation and enhances wear resistance. Although martensitic transformation and surface hardening also occur in the HS structure, the wear debris generated during sliding acts as a third-body abrasive, accelerating wear and degrading wear resistance. In contrast, the CG structure, which exhibits excellent low-temperature plastic deformation ability, shows only mild abrasion during the wear process.