工艺参数对激光增材熔覆成形Co基WC复合涂层的影响

Effect of Process Parameters on Co based WC Composite Coatings by Laser Additive Cladding Forming

采用9种不同的激光工艺参数在316L不锈钢基板上熔覆成形了Co基WC复合涂层。利用光学显微镜(OM)、扫描电子显微镜(SEM)和X射线衍射仪(XRD)检测了熔覆层的显微组织并分析了强化机制;利用显微硬度计和摩擦磨损实验机分析了熔覆层的横截面硬度分布和表面摩擦磨损性能。结果表明:激光功率分别为1.2 kW和1.6k W时成形的试件没有裂纹,物相组成不受激光功率和扫描速率的影响,主要由WC、Co和W2C相组成,但1.2 kW的激光功率会产生气孔等缺陷,导致成形试件硬度低于1.6 kW。又由于同一激光功率下受到扫描速率的影响,使参数为1.6 kW下10 mm·s-1的扫描速率的试件组织和性能最优,硬度最高达到1698 HV,摩擦系数为0.73。

Co based WC composite coatings were cladded on 316 L stainless steel substrate by 9 different laser process parameters.The microstructure of the cladding layer was detected by optical microscope(OM),scanning electron microscope(SEM)and X-ray diffractometer(XRD),respectively.The strengthening mechanism was analyzed.The cross section hardness distribution and surface friction and wear properties of the cladding layer were analyzed by microhardness tester and frictional wear tester,respectively.The results show that the specimens have no crack when the laser power is 1.2 kW and 1.6 kW,respectively,and the phase composition is not affected by laser power and scanning speed.The phase composition is mainly composed by WC,Co and W2 C phase,respectively.However,under the laser power of 1.2 kW,the blowholes and other defects appear,which lead to the hardness less than 1.6 kW.Moreover,due to the influence of scanning rates under the same laser power,the microstructure and properties of the samples under the paramters of 1.6 kW and 10 mm·s-1 is best,and the hardness reaches 1698 HV and the friction coefficient is 0.73.