Cr3C2对等离子钴基堆焊层组织及性能的影响

采用等离子堆焊技术在低碳钢表面制备钴基合金堆焊层(Co40)及添加质量分数20%和40%Cr3C2的钴基合金复合堆焊层(Co40+20%Cr3C2,Co40+40%Cr3C2)。利用光学显微镜、扫描电镜、X射线衍射仪以及磨损实验机等研究不同添加量的Cr3C2对钴基合金堆焊层组织和耐磨性能的影响。结果表明:Co40堆焊层由γ-Co和Cr23C6组成;添加Cr3C2粉末后,堆焊层出现未熔的Cr3C2和Cr7C3及Cr23C6相,且明显改变了其组织特征,Co40+20%Cr3C2堆焊层仍以亚共晶方式结晶,但其组织得到明显的细化和均匀化,而Co40+40%Cr3C2堆焊层转变为过共晶方式结晶,其组织由大量初生碳化物和枝晶组织组成;Co40+Cr3C2复合堆焊层的硬度和耐磨性较Co40堆焊层均得到显著提高,且随着Cr3C2添加量的增加而相应提高。

Effect of Cr3C2 on Microstructure and Properties of the Co-based Alloy Coatings Produced by Plasma Transferred Arc Weld-surfacing Process

The Co-based alloy coating （Co40） and the Co-based composite coating with 20% and 40%Cr3Ca particles （Co40＋ 20%Cr3C2, Co40＋40%Cr3C2） on low carbon steel substrate were obtained by plasma surfacing. The effects of Cr3C2 on the microstmcture and wear resistance of the Co40 coatings were investigated by means of various techniques, including optical microscopy, SEM, XRD and abrasion test. Results show that the Co40 coating is composed of 3＇-Co and Cr23C6 phase, and the C040＋Cr3C2 composite coatings are comtx）sed of y-Co, Cr23C6, Cr7C3 and not melted Cr3C2. The addition of Cr3C2 can change the solidification characteristic of the C040 coatings. Compared with the C040 coating, the microstructure of the C040＋ 20%Cr3C2 composite coating is refined and homogenized although crystallizing by hypoeutectic way. The C040＋40%Cr3C2 composite coating is composed of the primary carbide and the dendrite microstmcture crystallizing by hypereutectic way. The hardness and wear resistance of the composite clad layers was significantly improved compared with the C040 clad layer, and the hardness and wear resistance of C040＋40%Cr3Ca coating is better than those of C040＋20%Cr3C2 coating.