电子束偏转扫描对TC18钛合金组织、硬度和作用深度的影响

Effects of Deflection Scanning of Electron Beam on Microstructure, Hardness and Treated Depth of TC18 Titanium Alloy

摘要:

为了形成均匀的表面硬化层,采用逐行、无搭接的电子束高频偏转扫描技术(DSEB)对 TC18 钛合金的表面进行处理。重点研究了电子束束流、聚焦电流和处理次数等关键参数对TC18组织、表面硬度和处理深度的影响。处理的试样通过电镜扫描(SEM)、光镜和维氏硬度计进行检测。经 DSEB 处理后,TC18 钛合金表面形成了主要由针状马氏体组成的表面硬化层,表面硬度得到提高；硬化区的金相组织均匀,在扫描束斑相邻区域没有明显的过渡；硬化层深度均匀,可达200 μm以上。试验结果表明 DSEB 有望成为大面积、复杂形状的钛合金构件的表面处理新方法。

Abstract:

In this study, the high frequency deflection scanning of vacuum electron beam technology (DSEB) with line by line scanning mode and no overlap was employed to treat with the surface of TC18 titanium alloy, for obtaining a homogeneous hardened surface layer. The purpose of this work was to investigate the effects of critical process parameters, including beam current, focus current and treatment times, on the microstructure, hardness and treated depth of the treatment area. The treated specimens were characterized by using SEM, Optical Microscope, and Vickers hardness tester. After treated by DSEB, the hardened surface layer is formed, which is mainly consisted of the acicular martensite, and the surface hardness of the treatment area is improved. Moreover, the microstructure of the hardened zone is homogeneous and has no obvious transition at the contact parts of two adjacent electron beams scanning. The depth of the hardened zone can be more than 200 μm and basically constant. These results show that DSEB is a very promising technological solution for the surface heat treatment of titanium alloy of large area and complex components.