电弧沉积条件下Cu基熔覆层的微观组织及性能研究

Study on Microstructure and Properties of Cu based Cladding Layer under Arc Deposition

为了优化Q345B低碳钢的表面使用性能,设计相应的药芯焊丝并采用TIG沉积方法制备了Cu基熔覆层,通过OM、SEM、EDS、XRD和显微硬度测试等方法,研究了Cu基熔覆层的微观组织、元素分布、物相组成、界面元素扩散和表面硬度等。结果显示,在成分过冷的影响下,Cu基熔覆层由界面至顶部形成了不同的晶粒形貌。熔覆层主要由FCC结构的Cu-Ni-Cr-Fe固溶体、富Cr析出相和单质C元素组成,其中,由于微观偏析的存在,固溶体内元素分布不均匀,Ni、Fe元素主要富集在枝晶内,在枝晶间浓度较低;富Cr析出相主要以球状或棒状分布在基体上,少量单质C也在基体内均匀分布。研究表明,得益于合金元素的固溶强化和第二相粒子的第二相强化作用,熔覆层平均硬度达到202.8 HV_(0.1),高于纯铜和Q345B基体。

In order to optimize the surface performance of Q345B low carbon steel,the corresponding flux-cored welding wire was designed and the Cu based cladding layer was prepared by TIG deposition method.The microstructure,element distribution,phase composition,interface element diffusion and surface hardness of Cu based cladding layer were studied by OM,SEM,EDS,XRD and microhardness test.The results show that under the influence of compositional supercooling,different grain morphologies are formed in the Cu based cladding layer from the interface to the top.The cladding layer is mainly composed of Cu-Ni-Cr-Fe solid solution of FCC structure,Cr-rich precipitation phase and elemental C element.Among them,due to the existence of microsegregation,the distribution of elements in the solid solution is not uniform,and Ni and Fe elements are mainly concentrated in In the dendrite,the concentration between the dendrites is low.The Cr-rich precipitation phase is mainly distributed on the matrix in a spherical or rod shape,and a small amount of elemental C is also uniformly distributed in the matrix.The results show that benefiting from the solid solution strengthening of alloy elements and the second phase strengthening effect of the second phase particles,the average hardness of the cladding layer reaches 202.8 HV_(0.1),which is higher than that of pure copper and Q345B matrix.