表面纳米化对316L不锈钢干摩擦性能的影响

目的研究表面纳米化316L不锈钢干摩擦磨损性能,以获得合理的喷丸时间,提高316L不锈钢的使用寿命。方法采用普通喷丸强化方法对316L不锈钢进行表面纳米化处理,利用洛氏硬度计测量了纳米化前后材料表面洛氏硬度;利用激光共聚焦显微镜观察了纳米化前后材料表面三维形貌,测量了材料表面的粗糙度;利用扫描电子显微镜观察了表面纳米化处理后横截面的金相组织;利用材料表面性能综合测试仪在干摩擦条件下进行了摩擦磨损实验,测量了材料的摩擦系数;利用扫描电子显微镜观察了磨痕表面形貌,分析了材料的磨损机理。结果与未纳米化试样相比,喷丸时间为15 min时,表面硬度提高9.7%,而表面粗糙度降低17.6%,干摩擦系数降低17.3%;喷丸时间为30 min时,表面硬度提高34.1%,粗糙度降低35.1%,干摩擦系数降低28.8%。未纳米化试样呈现典型的粘着磨损和磨粒磨损机制,而纳米化处理后试样则主要呈现疲劳磨损和磨粒磨损机制。结论表面纳米化处理后试样表面硬度随处理时间的增加而增加,粗糙度随处理时间的增加而降低,干摩擦系数随处理时间的增加而减小。喷丸处理时间较短时以疲劳磨损为主,处理时间较长时以磨粒磨损为主。

Effects of Surface Nanocrystallization on Dry Friction Properties of 316L Stainless Steel

The work aims to obtain a reasonable shot blasting time and improve the service life of 316L stainless steel by studying dry friction and wear properties of 316L stainless steel subject to surface nanocrystallization. Normal shot peening method was used to apply surface nanocrystallization treatment to 316L stainless steel. The surface Rockwell hardness for nanocrystallized and un-nanocrystallized samples was measured by Rockwell hardness meter. Three-dimensional morphology of nanocrystallized and un-nanocrystallized samples was observed by laser confocal microscope. The surface roughness was also measured. The cross-sectional metallographic structure of samples after nanocrystallization was observed by scanning electron microscope. Friction coefficient of the material was measured by taking advantage of friction and wear experiment with a surface performance general-purpose tester under dry friction conditions. The grinding surface morphology was observed by scanning electron microscope and wear mechanism of the material was discussed as well. Compared with un-nanocrystallized samples, after shot blasting for 15 min, surface hardness of nanocrystallized samples increased by 9.7%, surface roughness reduced by 17.6% and dry friction coefficient reduced by 17.3%. After shot peening for 30 min, the surface hardness increased by 34.1%, surface roughness reduced by 35.1% and dry friction coefficient reduced by 28.8%. Un-nanocrystallized samples mainly showed fatigue wear and abrasive wear mechanism. In conclusion, the sample surface hardness after surface nanocrystallization increases with the increase of treatment time while both roughness and dry friction coefficient decrease with the increase of treatment time. The wear mechanism in a short shot peening is mainly fatigue wear, and that in a long shot peening is mainly abrasive wear.