304不锈钢纳米晶粒表层液体氮碳共渗后的结构和力学性能

Structure and mechanical properties of liquid nitrocarburized 304 stainless steel with a nanocrystalline surface layer

采用表面机械研磨处理(SMAT)在304不锈钢表面形成纳米晶粒表层,对粗晶粒和表面纳米化的304不锈钢试样采用一种较为环保的新型介质在450℃进行氮碳共渗(分别标记为CG-NC和SNC-NC试样)。结果表明,氮碳共渗的两种试样表面光滑,表层主要由含氮的S相组成,但SNC-NC试样仍保留纳米晶粒的表面结构。SNC-NC试样的氮原子扩散深度(13.3μm)、硬度(1040 HV0.05)和耐磨性都高于CG-NC试样(8.2μm,780 HV0.05)。

A nanocrystalline surface layer was generated on 304 stainless steel by the surface mechanical attrition treatment （SMAT） technique. The coarse grained and the surface nanocrystallized 304 stainless steel samples were salt bath nitrocarburized by using a newly developed environment friendly salt medium at 450 ℃ （noted as CG-NC and SNC-NC samples, respectively）. The results show that the both treated samples have smooth surface, and the surface layers are mainly composed of N containing S phase, but SNC-NC sample still maintains nano-sized grains at the surface layer. The SNC-NC sample has larger N diffusion depth （13.3 μm）, higher hardness （ 1040 HV0. 05） and better wear resistance than the CG-NC sample （8. 2 μm, 780 HV0.05）.