Microstructure and Wear Resistance of Ni-Cr Alloy Laser Cladding Layer with High Cr Content  

高Cr含量的Ni-Cr合金激光熔覆层组织与耐磨性能

作　　者：Pan Chaoyang Liu Zongde Shen Yue Lu Xinjie Mao Jie Wang Xinyu Li Jiaxuan 潘朝阳;刘宗德;申越;路鑫杰;毛洁;王鑫宇;李家璇(华北电力大学电站能量传递转化与系统教育部重点实验室,北京102206)

机构地区：[1]Key Laboratory of Power Station Energy Transfer Conversion and System,Ministry of Education,North China Electric Power University,Beijing 102206,China

出　　处：《稀有金属材料与工程》2024年第9期2438-2445,共8页Rare Metal Materials and Engineering

摘　　要：Four kinds of Ni-xCr alloy laser cladding layers(x=20,40,60 and 80,wt%)were prepared by high-speed laser cladding technique,and the relationship between microstructure and wear resistance of Ni-Cr alloy laser cladding layers with different Cr contents was investigated.The results show that the four Ni-Cr alloy laser cladding layers all have reticulated dendritic structures.Among them,Ni-20Cr and Ni-40Cr are single-phaseγ-(Ni,Cr)solid solutions,and their wear mechanisms are adhesive wear and abrasive wear.With the increase in Cr content,Ni-60Cr and Ni-80Cr areγ-(Ni,Cr)phase and Cr phase,as well as Cr-rich precipitates,and their wear mechanisms are adhesive wear,abrasive wear and fatigue wear.A moderate increase in Cr content can enhance the hardness and wear resistance of Ni-Cr alloy laser cladding layer.However,excessive addition of Cr results in the precipitation of Cr-rich precipitates.The hardness of these precipitates is 2430.4 MPa,which is lower than the hardness of the Ni-60Cr matrix(4024.86 MPa)and Ni-80Cr matrix(7022.68 MPa).A hardness transition zone exists between the Cr-rich precipitates and the matrix.Cracks are likely to initiate and expand in this zone,leading to deep spalling,which is not conducive to the wear-resistant properties of the laser cladding layer.Ni-80Cr has the highest hardness,but its high Cr content leads to a large number of penetrating cracks and Cr-rich precipitates on the surface,ultimately resulting in the worst wear resistance.Ni-60Cr exhibits the best wear resistance due to its high hardness and dense microstructure.采用高速激光熔覆技术制备了4种Ni-xCr合金熔覆层(x=20、40、60和80,质量分数),研究了不同Cr含量的Ni-Cr合金熔覆层的显微组织与耐磨性能的关系。结果表明,4种Ni-Cr合金熔覆层的组织均为网状枝晶结构。其中,Ni-20Cr和Ni-40Cr为单相的γ-(Ni,Cr)固溶体,其磨损机制为粘着磨损和磨粒磨损。随着Cr含量的增加,Ni-60Cr和Ni-80Cr为γ-(Ni,Cr)相和Cr相,且存在富Cr沉淀物,磨损机制为粘着磨损、磨粒磨损和疲劳磨损。适度增加Cr含量可以提高Ni-Cr合金熔覆层的硬度和耐磨性。然而,过量添加Cr会导致富Cr沉淀物的析出。这些沉淀物的硬度为2430.4 MPa,低于Ni-60Cr基体(4024.86 MPa)和Ni-80Cr基体(7022.68 MPa)的硬度。富Cr沉淀物与熔覆层基体之间存在硬度过渡区,裂纹极易在过渡区萌生并扩展,造成深层剥落,不利于熔覆层的耐磨性能。Ni-80Cr的硬度最高,但其Cr含量过高导致表面存在大量的贯穿性裂纹和较多的富Cr沉淀物,最终表现出最差的耐磨性能。Ni-60Cr拥有较高硬度和致密的微观结构,因此表现出最好的耐磨性能。

关 键 词：Ni-Cr alloy laser cladding Cr-rich precipitate wear resistance 

分 类 号：TG1[金属学及工艺—金属学]