45钢表面电子束微熔抛光的性能和组织分析

Properties and microstructure of 45 steel surface processed by electron beam micro melting polishing

关键词:  电子束  抛光  45钢  表面粗糙度  显微组织

Key words:  electron beam  polishing  45 steel  surface roughness  microstructure

摘要:

为显著改善45钢表面粗糙度及其综合力学性能. 文中采用电子束微熔抛光技术，对45钢表面进行电子束微熔抛光处理. 研究电子束抛光对表面粗糙度、改性层组织和硬度的影响，探讨了电子束扫描电流、扫描速度对表面粗糙度、改性层组织的影响规律. 结果表明，45钢经表面抛光处理后，表面粗糙度值由2.091 μm降到0.738 μm，降幅为64.7%；其表面改性层可分为抛光层区、热影响区和基体区；抛光层区的显微组织为针状马氏体，硬度为950 ~ 913 HV；热影响区的组织为针状马氏体和铁素体，硬度为855 ~ 280 HV；基体区的组织为珠光体和铁素体，硬度为244 ~ 204 HV. 电子束工艺参数对抛光后的表面粗糙度值影响显著，在满足抛光效果的条件下，改性层的厚度随电子束扫描电流的增加而增大，随扫描速度的增加而减小.

Abstract:

Process the surface of 45 steel was carried out in order to significantly improve the surface roughness and comprehensive mechanical properties of 45 steel using electron beam micro melting polishing technology. The influences of electron beam polishing on surface roughness, microstructure and hardness of the modified layer were studied. The influences of electron beam scanning current and scanning speed on surface roughness and microstructure of modified layer was also discussed. The results show that the surface roughness of 45 steel reduced from 2.091 μm to 0.738 μm. The decrease rate is 64.7%. The surface modification layer can be divided into the polishing zone, the heat affected zone and the matrix zone. The microstructure of the polishing layer is acicular martensite with 950 ~ 913 HV hardness. The microstructure of the heat affected zone are acicular martensite and ferrite with 855 ~ 280 HV hardness. The microstructure of the matrix zone are pearlite and ferrite with a hardness of 244 ~ 204 HV. The influence of electron beam processing parameters on the surface roughness after polishing is significant. Under the corresponding polish effect condition, thickness of the modified layer increases with the increasing of the scanning current of electron beam, and decreases with the increasing of scanning speed.