(1. 北京航空制造工程研究所,北京 100024;
2. 大连理工大学 材料科学与工程学院,大连 116085;
3.南京航空航天大学 机电学院,南京 210016)
摘 要: 利用金相显微镜、X射线衍射仪和扫描电镜对置氢Ti-6Al-4V合金的微观组织和相组成及切屑形貌进行了观察分析,采用分离式Hopkinson压杆试验测试置氢Ti-6Al-4V合金的动态力学性能,研究氢对Ti-6Al-4V切屑形成过程及切屑形态的影响,探讨置氢Ti-6Al-4V合金的切屑形成机制。结果表明:置氢后Ti-6Al-4V合金切屑的收缩系数增加,表面层片结构尺寸减小,切屑锯齿化程度减轻;氢含量低于0.4%(质量分数)时,局部材料热塑失稳是形成锯齿切屑的主要原因,随氢含量增加,钛合金切屑的绝热剪切现象减轻,随着氢含量的进一步增加,锯齿切屑的形成是由微裂纹而致。
关键字: Ti-6Al-4V合金;置氢;切屑形成;绝热剪切
cutting hydrogenated Ti-6Al-4V alloys
(1. Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024, China;
2. School of Material Sciences and Engineering, Dalian University of Technology, Dalian 116085, China;
3. School of Mecharonics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China)
Abstract:The microstructure and phase composition of hydrogenated Ti-6Al-4V alloys and the morphology of chip were observed optical microscopy, X-ray diffractometry and scanning electron microscopy. The split Hopkinson bar was employed to test the dynamic mechanical property. The morphology and mechanism of chip formation in cutting Ti-6Al-4V alloys were investigated. The results show: compared with unhydrogenated chip, the chip compression ratio of hydrogenated Ti-6Al-4V alloys is greater, the dimension of lamellae and saw-tooth are less significantly. The thermo-plastic instability is the mechanism of saw-tooth chips formation due to the large plastic deformation when the addition o hydrogen is less than 0.4% (mass fraction). In contrast, the crack initiation mechanism is responsible for the saw-tooth chip with more hydrogen content.
Key words: Ti-6Al-4V alloy; hydrogen treatment; chip formation; adiabatic shearing