文章编号：1004－5422(2021)04－0390－10

DOI:10.3969/j.issn.1004-5422.2021.04.010

IMI834钛合金高周及超高周疲劳裂纹萌生和扩展行为研究

刘  玉¹，刘宸汗¹，詹  敏²，汤  栋¹，何  超3，王清远^1，3 

（1.成都大学  机械工程学院，四川  成都  610106；2.成都大学建筑与土木工程学院，四川  成都  610109；

 3.四川大学  深地科学与工程教育部重点实验室，四川  成都  610065）

摘  要：为评估 IMI834 钛合金高周及超高周疲劳性能，揭示微观组织对其疲劳裂纹萌生及扩展行为的影响.采用旋转弯曲疲劳以及单轴拉压超声疲劳试验系统对材料疲劳性能进行了试验研究，并结合扫描电镜、电子背散射衍射技术和纳米压痕硬度测试等技术对合金材料的组织与疲劳性能关系进行了深入研究.结果表明:2种加载条件下材料具有较高的疲劳强度，裂纹萌生主要有2种模式，即短寿命状态下的表面萌生与长寿命状态下的内部萌生.合金材料内部存在大量晶粒取向相近且硬度值较低的α团簇结构，等轴状的α相内部以及α/β相界为裂纹萌生活跃点，而β相对裂纹扩展路径起阻碍、偏折的作用，β相的分布、取向是表面裂纹扩展路径的主要影响因素;应力比R=-1的超声疲劳加载条件下，材料高周疲劳裂纹为表面萌生，超高周疲劳裂纹由表面萌生转为内部萌生;粗糙区域是超高周疲劳过程中由裂纹引发的特征区域，并提出基于Pairs准则的粗糙区域内结构的演变过程.

关键词：钛合金；疲劳；裂纹萌生；裂纹扩展；微观组织

中图分类号：TG146.23         文献标识码：A

Study on High Cycle and Very High Cycle Fatigue Crack  Initiation and Propagation Behavior of IMI834 Titanium Alloy

LIU Yu¹,LIU Chenhan¹,ZHAN Min²,TANG Dong¹,HE Chao³,WANG Qingyuan^1,3

(1.School of Mechanical Engineering,Chengdu University,Chengdu 610106,China;

2.School of Architecture and Civil Engineering,Chengdu University,Chengdu 610106,China;

3.Key Laboratory of Deep Underground Science and Engineering,Ministry of Education,Sichuan University Chengdu 610065,China)

Abstract：In order to evaluate the high cycle and very high cycle fatigue properties of IMI834 titanium alloy, the effect of microstructure on the initiation and propagation of fatigue cracks was revealed. The rotating bending fatigue and uniaxial tensile compression ultrasonic fatigue test system was used to study the fatigue performance of the material, and the relationship between the microstructure and fatigue performance of the material was studied in depth by combining scanning electron microscopy, electron backscatter diffraction technology and nanoindentation hardness test.The results show that the material has high fatigue strength under two loading conditions, and the crack initiation mainly has two modes : ( a ) surface initiation under short life state, and ( b ) internal initiation under long life state. There are a large number of α cluster structures with similar grain orientation and low hardness in the material. The equiaxed α phase and the α/ β phase boundary are the active points of crack initiation, and β plays a role in hindering and deflecting the crack propagation path. The distribution and orientation of β phase are the main factors affecting the surface crack propagation path. Under ultrasonic fatigue loading with stress ratio R =-1, the high-cycle fatigue crack of the material is surface initiation, and the very high cycle fatigue crack changes from surface initiation to internal initiation. Rough area is the characteristic region caused by crack in the process of ultrahigh cycle fatigue, and the evolution process of structure in rough area based on Pairs Criterion is proposed.

Key words：titanium alloy;fatigue;crack initiation;crack propagation;microstructure