WC-Cr_(7)C_(3)复合增强铁基激光熔覆层的组织与性能

Microstructure and Properties of WC-Cr_(7)C_(3) Composite Reinforced Iron-Based Laser Cladding Layer

以铬粉、钨粉、石墨粉和铁粉为熔覆层原料,Ni60合金粉为黏结层原料,采用激光熔覆技术在45钢基体表面制备了WC-Cr_(7)C_(3)复合增强铁基熔覆层,研究了不同激光功率(2 500~3 500 W)和扫描速度(2~5mm·s^(-1))下熔覆层的宏观形貌,得到最优工艺参数,分析最优工艺下熔覆层的显微组织和性能。结果表明:最优激光熔覆工艺参数为激光功率3 500 W和扫描速度2mm·s^(-1);熔覆层中原位自生了网络结构的WC-Cr_(7)C_(3)复合碳化物,由熔覆层表面到内部其组织逐渐由等轴晶和树枝晶向柱状晶和平面晶转变;熔覆层的平均硬度为507.6 HV,较基体提高约63.8%,平均稳定摩擦因数为0.128,仅为基体的1/4,磨损率为4.9×10^(5)cm^(3)·N^(-1)·m^(-1),仅为基体的1/9,磨损形式为轻微的磨粒磨损和轻微的黏着磨损。

Taking chromium powder,tungsten powder,graphite powder and iron powder as cladding layer raw materials,and Ni60 alloy powder as bonding layer raw material,WC-Cr_(7)C_(3)composite reinforced iron-based cladding layer was prepared on the surface of 45 steel substrate by laser cladding technique.The macroscopic morphology of the cladding layer under different laser power(2 500-3 500W)and scanning speed(2-5mm·s^(-1))was studied to determine the optimal process parameters,and the microstructure and properties of the cladding layer under the optimal process were analyzed.The results show that the optimal laser cladding process parameters were the laser power of 3 500W and the scanning speed of 2mm·s^(-1).The WC-Cr_(7)C_(3)composite carbides with network structure were in situ spontaneously generated in the cladding layer.From the surface to the interior of the cladding layer,the microstructure gradually changed from equiaxed and dendrite to columnar and plane crystal.The average hardness of the cladding layer was 507.6HV,which was about 63.8%higher than that of the matrix.The average stable friction coefficient was 0.128,which was only one forth of the matrix,and the wear rate was 4.9×10^(5)cm^(3)·N^(-1)·m^(-1),which was only one ninth of the matrix;the wear form was slight abrasive wear and slight adhesive wear.