目的 提高旋转式割草机割刀耐磨性能和切割锋锐性能，以实现刃具的长寿命作业和对作物的低损伤收获。方法 采用固体稀土催渗碳氮硼共渗，对割刀后刀面及刀尖进行局部化学热处理，通过扫描电子显微镜、光学显微镜及显微硬度计对共渗层组织、微区成分及硬度分布进行检测，探讨割刀作业过程中形成自磨锐特性，并进行田间试验验证。结果 割刀经850 ℃×4 h稀土催渗碳氮硼共渗后，后刀面及刀尖表面由硼化物层(厚度约50~70 μm)和碳氮共渗层(厚度约750~1000 μm)组成，刃口处经高频加热油淬后，外层硼化物由于共晶重熔使硬度有所增加。共渗割刀在厚度方向上实现了组织、成分和硬度的梯度均匀变化，碳氮共渗层对表面高硬硼化物支撑能力有较大提升。作业过程中，割刀后刀面及刃口处的表层硼化物硬度高、耐磨性好，不易剥落及崩刃，使用寿命长，刃口突出可始终保持锋锐的切割性能，从而形成了自磨锐特性，实现了对再生作物的低损伤切割。田间试验结果表明，与市售割刀相比，共渗割刀耐磨性较高，长时间作业后仍能保持锋锐的切割性能，有利于作物切口的愈合与再生。结论 稀土催渗碳氮硼共渗的割刀，由于组织、成分、硬度的梯度均匀变化，在作业过程中形成自磨刃，实现了刃具的长寿命作业和对作物的低损伤收获。

The work aims to improve the properties of wear resistance and cutting sharpness of rotary mower cutter, so as to realize the long service life of blades and lower the damage to crops. The flank surface and tip point of blades were heat-treated by carbon-nitron-boronized with rare elements catalysis technique. Scanning electron microscope (SEM), optical microscope (OM) and microhardness tester were used to detect the microstructure, components and hardness distribution of co-infiltrated layer. The self-sharpening characteristic formation mechanism of blades in the operation process was studied and verified with field test. After treatment of carbon-nitron-boronized with rare elements catalysis (850 ℃×4 h), the flank surface and tip point of blades were composed of boride layer (about 50~70 μm thickness) and carbonitriding layer (about 750~1000 μm thickness). The cutting edge hardness of boride increased due to hypereutectic treatment after high frequency induction quenching in oil. Therefore, gentle gradient variation of microstructure, components and hardness of heated blades was exhibited following the thickness direction and the support ability of carbonitriding layer to external boride layer remarkably increased. In the working process, the blades had longer serve life due to higher hardness flank surface and cutting edge, excellent wear resistance as well as difficult peeling and edge flaking. The protruding cutting edge could always keep sharp cutting performance, thus forming self-sharpening characteristics and realizing low-damage cutting of regenerated crops. The results of field test indicated that compared with the blades available in the market, the co-infiltrated blades had higher wear resistance and could still keep the sharp cutting performance after long-term operation, which was conductive to the healing and regeneration of crop cutting damage. The blades after treatment with carbon-nitron-boronized with rare elements catalysis technique can form the self-sharpening characteristic in the operation process because of uniform gradient microstructure, components and hardness distribution for the flank surface and tip point, thus realizing the long service life and lowering damage to crops.