Objective of the current study is to investigate the effect of plastic deformation before and after nitriding on nitrogen (N) and hardness distribution as a function of depth. AISI316 stainless steel samples were subjected to ultrasonic shot peening (USP), nitriding, USP followed by nitriding and nitriding followed by USP. USP prior to nitriding led to higher N uptake by expanded austenite and N diffusion to deeper regions contributing to enhanced hardened depth. USP after nitriding led to N redistribution from expanded austenite to diffusion zone leading to decreased surface hardness and increased hardened depth as compared to nitrided case. Interestingly, the level of compressive residual stress remained the same irrespective of whether USP is carried before or after nitriding. USP after nitriding induced intense deformation of the surface but with reduced deformed depth that attributed to the ability of nitrided region to sustain higher deformation loads than the base metal.

Graphical abstract

中文翻译：

---

严重塑性变形对 316 不锈钢渗氮前后条件的影响

本研究的目的是研究渗氮前后塑性变形对氮 (N) 和硬度分布随深度变化的影响。AISI316不锈钢样品经过超声喷丸（USP）、渗氮、USP后渗氮和渗氮后USP。氮化前的 USP 通过扩大奥氏体和 N 扩散到更深的区域导致更高的 N 吸收，从而有助于提高硬化深度。与氮化处理相比，氮化后的 USP 导致 N 从膨胀奥氏体重新分布到扩散区，导致表面硬度降低和硬化深度增加。有趣的是，无论是在氮化之前还是之后进行 USP，压缩残余应力的水平都保持不变。

图形概要