镍基钎料对45~#钢激光熔覆镍基WC合金熔覆层缺陷的影响

Effect of Ni-based Solder on Defects of Laser Cladding WC Alloy Layers on 45~# Steel

目的改善Ni60A+WC合金粉末激光熔覆中裂纹和气孔等缺陷性能。方法在Ni60A+WC合金粉末中添加膏状镍基钎料(BNi-1a)改善激光熔覆层的裂纹和气孔缺陷。使用Rofin FL020光纤激光器,在1 kW功率、扫描速度为4 mm/s、光斑直径约为2 mm的条件下,对经过烘干的预涂覆合金熔覆层进行激光加工处理。通过显微硬度测试评价熔覆层的硬度,通过扫描电子显微镜和X射线衍射仪对熔覆层形貌、相组织进行分析,并通过UMT和表面形貌仪对熔覆层的摩擦系数和耐磨性进行评估。结果在Ni60A+WC合金粉末中添加膏状镍基钎料(BNi-1a),优化了Cr和C合金相的组成,使熔覆层的裂纹和气孔等缺陷明显减低。添加膏状镍基钎料的熔覆层的摩擦系数约为0.45,熔覆层的摩擦系数大约降低了18%。同时熔覆层的耐磨性也有所提高,未添加膏状镍基钎料的熔覆层磨痕横截面积约为0.70×10^(-3) mm^2,而添加膏状镍基钎料的熔覆层横截面积约为0.50×10^(-3) mm。结论镍基钎料(BNi-1a)的加入可以有效减少熔覆层的裂纹和气孔等缺陷,同时提高熔覆层的耐磨性,但是使熔覆层的硬度有一定的降低。

The work aims to reduce defects such as cracks and pores in laser cladding of Ni60A ＋WC alloy powder. Pasty Ni-based solder （BNi-1a） was added into Ni60A＋WC alloy powder to reduce defects such as cracks and pores in laser cladding layers. Provided with power of 1 kW, scanning speed of 4 mm/s and spot diameter of nearly 2 mm, Rofin FL020 fiber laser was used for laser processing of baked pre-coated alloy cladding layers. Microhardness test was conducted to evaluate hardness of the cladding layers, morphology and phase structure of the layers were studied with SEM and XRD. Friction coefficient and wear resistance of the layers were evaluated with UMT and surface morphology tester. Composition of Cr and C alloy phase was optimized, and defects such as cracks and pores were reduced by as pasty Ni-based solder （BNi-1a） was added into Ni60A＋WC alloy powder. For the cladding layer with pasty Ni-based solder, friction coefficient was nearly 0.45, friction coefficient of the cladding layer decreased by nearly 18%, wear resistance was also greatly increased, and cross-sectional area was nearly 0.50？10？3 mm. For the cladding layer without pasty Ni-based solder, cross-sectional area of the grinding crack was nearly 0.70？10？3 mm2. The addition of Ni-based solder （BNi-1a） can effectively reduce defects including cracks and pores, and improve wear resistance and reduce hardness, but it may reduce hardness of cladding layers.