多层熔覆对激光熔覆层微观组织和硬度的影响

采用金相显微镜和硬度计研究了多层熔覆对激光熔覆层微观组织和硬度的影响.结果表明,两层熔覆层交界处的硬度变化规律为以界面为基准线,往第二层熔覆层方向硬度随距离的增加而逐渐增加,往第一层熔覆层方向随着距离的增加,硬度先降低后增加最后降低;在层间停光时间较长的情况下,熔覆层数的增加会使试样平均硬度有所下降,靠近基材的熔覆层硬度低于远离基材的熔覆层硬度,多层激光熔覆不同层的组织没有明显差异;在层问停光时间极短的条件下,熔覆层数的增加会导致试样平均硬度急剧下降,靠近基材的熔覆层硬度高于远离基材的熔覆层硬度,多层激光熔覆不同层的组织有明显差异.

Influence of Multilayer Cladding on Microstructure and Hardness of Laser-Clad Layers

The influences of multilayer cladding on the microstructure and hardness of laser-clad layers were studied by metallographic microscope and hardometer.The results show that the hardness change rule along adjacent layers is as the interface is datum line,the hardness will increase with the increase of distance along the second layer,and with the increase of distance along to the first layer,the hardness will decrease firstly,and then increase,and decrease lastly;when the ceasing time of laser scanning between adjacent layers is relatively long,the increase of clad layers will result in decrease of average hardness of specimen,and the hardness of layer which is near the substrate is lower than that which is far from the substrate,furthermore,the microstructure of different layers in multilayer cladding has no obvious difference;when the ceasing time of laser scanning between adjacent layers is very short,the increase of clad layers will result in sharply decrease of average hardness of specimen,and the hardness of layer which is near to the substrate is higher than that which is far from the substrate,furthermore,the microstructure of different layers in multi-layer cladding has obvious difference.