Q235钢表面激光熔注WC涂层的微观组织及耐磨性

Microstructure and wear property of surface modification layer produced by laser melt injection WC on Q235 steel

关键词:  激光熔注  碳化钨  微观组织  耐磨性能

Key words:  laser melt injection  WC  microstructure  wear-resistant property

摘要:

采用激光熔注技术对材料进行表面强化具有显著的优点.将WC陶瓷作为注入颗粒,在Q235钢表面制备激光熔注层.对激光熔注工艺进行了系统研究.利用SEM,EDS,XRD等手段分析熔注层的微观组织结构,对熔注层的硬度和耐磨性能进行了测试.结果表明,成功的激光熔注过程需要严格的工艺参数条件,采用优化的工艺参数时激光熔注WC表面层成形良好.熔注层主要由WC,W₂C以及M₆C(Fe₃W₃C-Fe₄W₂C)强化相组成,Fe₃W₃C分别以颗粒之间基体上的树枝晶和依附WC颗粒形成的反应层两种形态存在于熔注层中;熔注层平均硬度约为母材硬度的4倍,熔注层摩擦系数不超过基体的1/4,熔注层耐磨性良好.

Abstract:

Laser melt injection (LMI) technology has great potential in the field of material surface modification.WC powder was injected into the surface of Q235 steel by LMI process,and the influence of process parameters was studied.The microstructure and composition of the coatings were analyzed by means of SEM,XRD and EDS.Hardness and wear-resistant property of the coatings was measured.The results show that successful LMI layer can be achieved only on the condition that process parameters meet the strict requirements.Through optimizing the process parameters,excellent coatings can be acquired.Microstructure in the coatings is complex,which consist of WC,W₂C,and M₆C (Fe₃W₃C-Fe₄W₂C) phases.The differences of Fe₃W₃C microstructure in the different zones of the coatings are obvious.The compositions of the reaction layers around particles and dendrite precipitation carbides in the upper coating are both Fe₃W₃C.The average hardness of LMI layer is about four times of that of Q235 steel.The friction coefficient of LMI layer is not over one quarter of that of the substrate,which indicates wear resistance of coatings enhanced sharply.