激光熔覆对轮轨材料摩擦磨损性能的影响

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Laser cladding of Co-based alloy on rail and wheel materials was carried out by CO2 laser. The microstructure and micro-hardness of the laser cladding layers were analyzed and tested. Friction and wear properties of the wheel/rail substrate and laser cladding Co alloy coatings were investigated using MMS-2A wear resistance machine. The results show that the high quality cladding coating without defects of pores and cracks and with the thickness of about 1 mm is ob- tained,which has an excellent metallurgical bonding with the substrate. The cladding layer mainly consists of these phases of T-Co, Cr23C6 and so on. There are some crystallization morphologies, such as planar, cellar, columnar and twin micro- structure. The micro-hardness of cladding layer of wheel and rail is respectively increased by 43% ,45% than that of sub- strate. Friction and wear properties of Co coatings are obviously better than those of wheel and rail materials. The wear re- sistance of coatings is improved about 4 times than that of substrate. The wear mechanism of cladding coatings is mainly ab- rasive wear.利用CO2激光器分别在车轮和钢轨材料表面熔覆一层钴基合金粉，分析熔覆层的微观组织结构和显微硬度，利用MMS-2A摩擦磨损试验机研究轮轨材料激光熔覆钴基合金粉前后的摩擦磨损性能。结果表明：激光熔覆可获得厚度1mm左右无气孔、裂纹且与基体冶金结合的优质激光熔覆层，熔覆层组织主要由γ-Co、Cr23C6等相构成，熔覆区主要有平面晶区、胞状晶区、树枝晶区；车轮和钢轨熔覆层的显微硬度分别比基体提高了43％和45％，激光熔覆后的轮轨摩擦磨损性能明显优于轮轨基体，耐磨性能比轮轨基体提高约4倍，激光熔覆后轮轨的磨损机制主要表现为磨粒磨损。