Abstract: In order to improve the mechanics properties of high hardness lasers cladding layers, in the laser cladding processes, a class of sinusoidal alternating magnetic field was applied. The high hardness alloy cladding layers were prepared on the Q235A surface. The tensile tests, the impact tests, the fracture analyses, the microstructure observations, the phase analyses, the micro hardness tests and the comparative analyses of wear resistance of the test specimens were carried out. The effects of alternating magnetic field on the mechanics properties and microstructures of the cladding layers were studied. Research results show that in the laser cladding processes, the loading intensity is as 50mT and the frequency is as 20Hz, the tensile strength of the sample may be increased by about 9%, extension rate is increased by about 1%, impact toughness increased by about 11%, and the tensile fracture surfaces are obviously tough, material organizations are more detailed and dense; The microhardness of the cladding layers increase with the increase of the magnetic induction strength,but the changes of magnetic field frequency are very small. When the alternating frequency is as 25Hz, the magnetic field amplitude is as 60mT, the loss weight of the mill is reduced by 15%.

Key words: laser cladding, alternating magnetic field, cladding layer, mechanics property, microstructure

摘要： 为改善高硬激光熔覆层的力学性能，在激光熔覆过程中辅助施加类正弦交变磁场，在Q235A表面制备了高硬合金熔覆层。对熔覆试样进行拉伸和冲击性能测试、断口分析、显微组织观察、物相分析、显微硬度测试以及耐磨性对比分析，研究了交变磁场对熔覆层力学性能和微观组织的影响。研究结果表明：在激光熔覆过程中加载强度为50mT、频率为20Hz的交变磁场时，可使试样的拉伸强度提高约9%，延伸率提高约1%，冲击韧性提高约11%，且拉伸断口出现明显韧窝，材料组织更细化、致密；熔覆层显微硬度随着磁感应强度的增大而增大，但随磁场频率的变化极小；当交变频率为25Hz、磁场振幅为60mT时，熔覆试样磨损失重减小15%。

关键词: 激光熔覆, 交变磁场, 熔覆层, 力学性能, 微观组织