45钢电子束扫描相变硬化组织和硬度的研究

电子束表面处理可以提高钢铁材料的表面硬度和力学性能。研究电子束扫描对45钢硬化层组织和性能的影响,探讨电子束功率、扫描速度等工艺参数对硬化层组织和性能的影响。采用扫描电镜分析45钢电子束表面强化层的显微组织,用显微硬度计进行硬度测试。结果表明,45钢经电子束扫描处理后,硬化层的组织为针状和板条状马氏体,组织比常规调质处理更加均匀、细小,试样表面的平均硬度达58 HRC,比淬火加低温回火处理的硬度高3～5 HRC,是调质处理的两倍,从处理表面往下沿深度方向硬度逐渐减小。电子束工艺参数对硬化层组织和性能有较大影响,硬化层宽度和深度随着电子束功率的增加而增加,随着扫描速度的增加而减小;硬化层的最高硬度随着电子束功率密度的增加而增加,随着扫描速度的增加而减小。

Research on the Microstructure and Hardness of Transformation Hardening of 45 Steel during Electron Beam Scanning

The surface hardness and mechanical properties of steel materials are both improved by means of scanning electron beam.The influence of electron-beam scanning on the transformation hardening of 45 steel is studied in this work.The effects of electron beam parameters,such as electron beam power,scanning speed and so on,on the microstructure and mechanical properties are discussed.The microstructure of the 45 steel electron beam surface hardened layers is analyzed by using scanning electron microscope,and the hardness is measured by microhardness tester.The experimental results show that the microstructures of hardened layers of 45 steel is needle and lath martensite after electron beam scanning,and is more uniform and compact than those which are treated by quenching and tempering.The surface hardness of hardened layers reach to 58 HRC,which is harder than that treated with quenching and low temperature tempering of 3～5 HRC,and is about as two times as that treated by quenching and tempering,the hardness is declined gradually alone the deep section from the treated surface.The hardened layer microstructure and mechanical properties are great influenced with electron beam parameters.The width and depth of the hardened layer and the max hardness of the hardened layer are increased greatly with electron beam power increasing,declined with scanning speed increasing.