激光沉积Ti-6Al-2Zr-Mo-V钛合金高周疲劳性能

 疲劳失效是钛合金工业应用中最重要的失效方式，疲劳强度是钛合金应用的关键性指标。为了研究激光沉积Ti-6Al-2Zr-Mo-V钛合金的疲劳性能和行为，在625 MPa到900 MPa不同应力水平下进行了室温高周疲劳(HCF)测试(应力比R=0.1,加载频率f=120~130 Hz)，完成了疲劳断口表面分析。研究了气孔存在及分布对激光沉积Ti-6Al-2Zr-Mo-V钛合金疲劳性能的影响。激光沉积钛合金具有细小α/β片层组织。分析结果显示，虽然疲劳源区有气孔存在，激光沉积Ti-6Al-2Zr-Mo-V钛合金仍然具有优异的疲劳性能。取向丰富细小的α/β片层组织能有效减小疲劳源区滑移长度。分析结果还表明，应力水平对疲劳行为有一定影响。

HCF Properties of Laser Deposited Ti-6Al-2Zr-Mo-V Alloy

Fatigue failure is the most important failure mode in industrial applications of titanium alloys while fatigue strength is the critical mechanical property. First, the fatigue properties of laser deposited Ti-6Al-2Zr-Mo-V alloy are studied. High-cycle fatigue (HCF) test is conducted at room temperature at several different stress levels ranging from 625 MPa to 900 MPa, with a load ratio of 0.1 and a frequency of 120-130 Hz. Fatigue fracture surface is analyzed by scanning electron microscope (SEM). Then, the influence of micropores and their distribution on fatigue properties of laser deposited Ti-6Al-2Zr-Mo-V alloy is investigated. Fine α/β lamellar structure is obtained in laser deposited Ti-6Al-2Zr-Mo-V alloy. The examination results of high-cycle fatigue tests indicate that although micropores exist in the fatigue crack initiation regions, laser deposited Ti-6Al-2Zr-Mo-V alloy still has excellent fatigue properties. The fine α/β lamellar structure can effectively lend to the reduction of slip length in the crack initiation regions. Furthermore, the results also show that there is certain influence of stress level on fatigue behavior.