表面粗糙度对钛合金超高周疲劳性能的影响
发布人：上海艾荔艾合金股份有限公司www.shailiai.cn
更新时间：2016-03-03
采用自行研制的超声疲劳实验装置, 研究不同表面粗糙度下 Ti-6Al-4V 合金的超高周疲劳性能.
表面粗糙度对钛合金超高周疲劳性能的影响EFFECT OF SURFACE ROUGHNESS ON VERY HIGH CYCLE FATIGUE BEHAVIOR OF Ti-6Al-4V ALLOY采用自行研制的超声疲劳实验装置, 研究不同表面粗糙度下 Ti-6Al-4V 合金的超高周疲劳性能. 结果表明, 当表面凹痕宽深比 a/c (a 为凹痕宽度, c 为凹痕深度)在 2~10 之间时, Ti-6Al-4V 合金的临界凹痕深度在 0.49～1.10 µm 之间. 当表面凹痕深度小于临界深度时, 表面粗糙度对 Ti-6Al-4V合金的超高周疲劳性能没有影响. 当表面凹痕深度大于临界深度时, Ti-6Al-4V 合金疲劳寿命随表面粗糙度的增加而下降, 并且随着循环周次的增加, Ti-6Al-4V 合金疲劳性能对表面粗糙度的敏感性下降. 随着表面粗糙度的增加, Ti-6Al-4V 合金超高周疲劳裂纹的萌生方式发生变化. 超高周疲劳裂纹源有由 1 个向多个、由内部向次表面转移的趋势; 当表面凹痕深度增加到一定程度后, 在超高周疲劳寿命区间, Ti-6Al-4V 合金疲劳寿命随粗糙度的增加而大幅下降. 疲劳裂纹全部从合金表面凹痕根部处萌生, 没有内部萌生的情况.
Ti-6Al-4V alloys are widely used in aero engine blades for their unique properties, such as high specific strength, high specific stiffness and high fatigue strength. Aero engine blades usually suffer a variety of cyclic loading during the period of services, which finally results in fatigue failure. Fatigue life of materials is known to highly depend on the surface quality. Consequently, more and more researches about the influence of machined surface roughness on the fatigue behavior of materials have been carried out in the last decades. However, there are less relevant results about the relationship between surface roughness and very high cycle fatigue (VHCF) properties of Ti-6Al-4V alloy. To investigate the effects of surface roughness on fatigue properties of Ti-6Al-4V under very high cycle fatigue regimes, ultrasonic fatigue tests were conducted at the conditions of 20 kHz and stress ratio R=-1 at room temperature in air. During ultrasonic fatigue testing, each specimen was water-cooled. The specimen surfaces were cut and grinded which gave different surface roughness. The surface roughness was characterized using profilometry. In order to explain the high dependence of stress-fatigue life (S-N) curves on the surface roughness, an approach based on the finite element analysis of measured surface topography was proposed. The results show that the VHCF property of Ti-6Al-4V alloy was significantly affected by surface roughness. The critical flaw size was 0.49~1.10 µm when the ratio between spacing and height of circumferential grooves was between 2~10. When surface roughness was smaller than the critical flaw size, surface roughness exerted no influence on fatigue life. While surface roughness was greater than critical flaw size, fatigue life decreased with increasing surface roughness. Surface roughness played a more important role in long life regime than that in VHCF regime in which with the growth of surface roughness, the crack initiation site changed from single one to two or more ones, as well as changed from inside to subsurface. When the surface roughness was large enough, all cracks initiated from surface even in super long life regime.
作为值得信赖的合作伙伴和高品质金属合金的半成品供应商，艾荔艾拥有完善的服务体系和专业的团队。在同客户交易的过程中，我们力求根据不同的应用需求将我们的产品做到精益求精。针对当前和未来的市场需求，艾荔艾致力于为客户提供最佳的金属材料解决方案。
AILIAI has been a reliable partner and supplier of sophisticated and high-quality semi-finished products maed of alloys. In dialogue with our customers, we optimise our products to meet the specific application requirements. AILIAI develops the best alloy material solutions for current and future challenges.
获取更多我们供应的合金和服务信息，请致电086-021-67660801或发电子邮件kefu@ailiaigroup.com联系我们，您也可以通过微博，微信，领英和推特与我们互动。
For more information on the alloys and services that we supply, call us at 086-021-67660801 or email us at kefu@ailiaigroup.com. You can also get in touch on social media, we are constantly active on Weibo, Weixin, LinkedIn and Twitter.