摘要
选择W18Cr4V高速钢刀具作为测试基体,综合运用淬火与回火相结合的工艺处理基体。在其表面激光熔覆一层高硬度的CoMoN/WC涂层,实验测试分析各个回火温度得到的涂层硬度及其微观组织。研究结果表明:1)CoMoN/WC涂层跟基材达到了异冶金结合状态,在涂层内存Fe3W3C硬质相组织以及各类间隙态的化合物,使涂层获得很高的硬度。位于涂层中上区域存在大量的树枝晶与部分等轴晶,在中部区域形成了许多大尺寸树枝晶,在涂层底部存在许多小孔以及许多大尺寸的黑色组织。涂层形成了梯度硬度分布状态,相对于基体发生了硬度的大幅提升。三次回火+淬火循环处理涂层获得更高硬度;当回火温度上升后,涂层的硬度表现为不断减小。对试样进行高温处理后会引起晶粒的长大现象,同时减弱了组织细化的效果,形成了更多的位错数量。
The CoMoN/WC composite coatings,synthesized by laser cladding of a layer of CoMoN/WC powders pre-coated on W18 Cr4 V high-speed steel substrate,were modified by quenching/tempering cycles.The influence of the tempering temperature and quenching-tempering cycle number on the microstructures,hardness and red hardness of the CoMoN/WC coatings were investigated.The preliminary results show that the tempering temperature had a major impact.To be specific,the tissue refinement,formation of Fe3W3C and interstitial compounds significantly increased the hardness of the coatings.As the tempering temperature increased(in three cycles),the hardness decreased,because high temperature increased grain-size and dislocation density.Formation of hetero-metallurgical bonding enhanced interfacial adhesion.The fact that many dendrites and some equiaxed-grains occupied the top,larger dendrites controlled the middle,and high density of pores and large black clusters dominated the bottom explains the depth profile of hardness.
作者
程改兰
冯金广
陈正学
Cheng Gailan;Feng Jinguang;Chen Zhengxue(School of Mechanical and Electrical Engineering,Zhengzhou Vocational College of Information Technology,Zhengzhou 450008,China;School of Mechanical and Electrical Engineering,Henan Vocational and Technical College,Zhengzhou 450008,China;Henan Mechanical Design and Research Institute Co.,LTD.,Zhengzhou 450008,China)
出处
《真空科学与技术学报》
EI
CAS
CSCD
北大核心
2020年第5期432-436,共5页
Chinese Journal of Vacuum Science and Technology
