为了研究在激光熔覆修复工艺中, 激光扫描速率对最终形成的熔覆层性能的影响,采用同步送粉法, 利用激光熔覆工艺在QT500球墨铸铁上制备了不同扫描速率下的镍基合金熔覆层样本; 利用金相显微镜观察熔覆层的显微金相, 并使用显微硬度计对熔覆层显微硬度进行了测定与分析, 取得了熔覆层样品的硬度、显微金相组织以及样品稀释率等数据。结果表明, 在其它条件不变下, 随着激光扫描速率的增加, 熔覆层组织更加致密、均匀,熔覆层的平均显微硬度得到了显著提高; 以激光功率为1.9kW、扫描速率为5mm/s、光斑直径为4mm等参量得到的熔覆层组织与性能最优。此研究对激光熔覆表面强化工艺中合理选择工艺参量提供了理论依据。

In order to study effect of laser scanning speed on the properties of final cladding layer in laser cladding repair process, Ni-based alloy cladding samples were prepared on QT500 nodular cast iron by laser cladding at different scanning speeds under the condition of synchronous powder feeding.The metallographic microscope of the cladding layer was observed by metallographic microscope, and the microhardness of the cladding layer was measured and analyzed by means of microhardness tester. The hardness, microstructure and sample dilution ratio of the cladding samples were obtained. The results show that the microstructure and properties of the cladding layer would be better with the increase of the laser scanning speed.The microstructure of the cladding layer is more compact and the average microhardness of the uniform cladding layer is improved significantly with the increase of the laser scanning speed. The optimal parameters are laser power of 1.9kW, scanning speed of 5mm/s, and the diameter of the spot of 4mm. The study provides the theoretical basis for reasonable selection of process parameters in laser cladding surface strengthening process.