喷丸强化对TC11钛合金高周疲劳性能的影响  

High Cycle Fatigue Behavior of TC11 Titanium Alloy by Shot Peening Strengthening

作　　者：严振[1,2] 梁益龙[1,2] 张泽军 徐军[1,2] 易艳良 

机构地区：[1]贵州大学材料与冶金学院,贵州贵阳550025 [2]贵州省材料结构与强度重点实验室,贵州贵阳550025 [3]黎阳航空发动机有限公司,贵州贵阳550025

出　　处：《稀有金属》2014年第4期554-560,共7页Chinese Journal of Rare Metals

基　　金：贵州省重点攻关项目(黔科合GZ字[2011]3001)资助

摘　　要：主要研究TC11钛合金喷丸前后高周疲劳性能的改变情况,并对比研究了喷丸前后宏微观影响因素的变化。在疲劳试验前后采用X射线应力衍射仪(XRD)、金相显微镜、扫描电镜(SEM)、超微小显微硬度计等分析研究了喷丸强化对TC11钛合金高周疲劳性能的影响,并结合升降法和成组实验法测试喷丸前后两种不同表面状态下TC11钛合金的高周疲劳性能,拟合成两种不同表面状态下的疲劳S-N曲线。疲劳试验结果表明喷丸后在表层形成明显的残余压应力场和喷丸硬化现象,将裂纹萌生驱赶至次表面,显著提高了TC11疲劳强度和寿命。经喷丸后TC11钛合金试样疲劳强度极限达到616.5 MPa,而未喷丸试样疲劳强度极限仅为448 MPa,与之相比喷丸后疲劳强度极限增加了168.5MPa,提升幅度达37.6%。喷丸不仅使得试样表面完整性更为良好,减少了表面应力集中区,还使得表层组织中α相分布的致密度增加。喷丸硬化致使表层显微硬度值发生变化,形成一个深度有近260μm的梯度分布层,表面硬度达到HV433,较未喷丸相比也有近HV50的提升。喷丸后疲劳源深度达到258μm,较未喷丸试样的38μm相比增加达220μm。The changes of high-cycle fatigue properties of TCll titanium alloy before and after the shot peening were investigated. Simultaneously, the variations of macro and micro influence factors before and after the shot-peening were comparatively studied. During the fatigue experiment, X-ray stress diffraction （XRD） apparatus, metallurgical microscope, scanning electron microscope （ SEM）, ultra micro hardness tester, etc., were applied to analyze the influences of shot peening on high cycle fatigue behavior of TC11 titanium alloy. Based on the combined method of changing strength and grouping test, the high cycle fatigue behavior of TC11 titanium alloy in two different surface conditions of shot peening was studied. The results revealed that the residual compressive stress and structure strength drove the crack initiation to the subsurface initiation and obviously improved the fatigue life of TC11 titanium alloy after the shot-peening. After blasting of TCll titanium specimen, the fatigue strength limit reached 616.5 MPa, and the fatigue strength limit of the sample of unpeened came up to 448 MPa. Moreover, compared with the unpeened fatigue strength limit, the fatigue strength limit increased by 168.5 MPa （ about 37.6% ） after blasting. Blasting not only made the integrity of the sample surface more favorably redace the surface stress concentration area, but also developed the density of a-phase distribution in the surface tissue. Surface microhardness was influenced by pill hardened, and the microhardness formed a gradient layer with depth of about 260 μm. Meanwhile, the peening surface hardness increased to HV433 （ HV50 higher than that of unpeened one）. The depth of source of fatigue increased by 220 μm compared with that without blasting, and finally came up to 258 μm after blasting.

关 键 词：喷丸强化 高周疲劳 TC11钛合金 S-N曲线 

分 类 号：TG178[金属学及工艺—金属表面处理]