IMECH-IR  > 非线性力学国家重点实验室
微结构和应力比对Ti-6A1-4V高周和超高周疲劳行为的影响
Alternative TitleEFFECTS OF MICROSTRUCTURE AND STRESS RATIO ON HIGH-CYCLE AND VERY-HIGH-CYCLE FATIGUE BEHAVIOR OF Ti-6A1-4V ALLOY
刘小龙; 孙成奇; 周砚田; 洪友士; Hong, YS
Source Publication金属学报
2016
Volume52Issue:8Pages:923-930
ISSN0412-1961
Abstract

采用旋转弯曲和超声疲劳实验分别测试了全等轴和等轴双态组织Ti-6A1-4V合金的高周和超高周疲劳性能,并用SEM观察了疲劳断口特征.结果表明:2种组织T1-6A1-4V合金的高周和超高周疲劳行为相似,不同应力比下,其S-N曲线均表现出单线形或双线形的形式;存在滑移机制和解理机制2种疲劳破坏机制.随应力比增加,2种组织Ti-6A1-4V合金的高周和超高周疲劳破坏机制均从滑移机制向解理机制转变.基于疲劳寿命和疲劳强度建立模型分析了应力比对2种机制之间竞争行为的影响,模型预测结果与实验结果趋势吻合.

Other Abstract

Titanium alloys have been widely used as superior engineering materials because of their high specific strength, high temperature resistance and high corrosion resistance. In their engineering applications such as used in aircraft engines, titanium alloys may experience even 10~(10) fatigue cycles. Recently, faceted crack initiation was observed in high-cycle fatigue (HCF) and very-high-cycle fatigue (VHCF) regimes of titanium alloys, which resulted in a sharp decrease in fatigue strength. Therefore, the HCF and VHCF of titanium alloys have both scientific significance and engineering requirement. In this work, the effects of microstructure and stress ratio (R) on HCF and VHCF of a Ti-6A1-4V alloy have been investigated. Fatigue tests were conducted on a rotating-bending fatigue machine and an ultrasonic fatigue machine. All the fatigue fracture surfaces were observed by SEM. The results show that the HCF and VHCF behaviors of the fully-equiaxed and the bimodal Ti-6A1-4V alloy are similar. The observations of fracture surface indicate that two crack initiation mechanisms prevail, i.e. slip mechanism and cleavage mechanism. With the increase of stress ratio, the crack initiation mechanism switches from slip to cleavage. The S-N curves present the single-line type or the bilinear type. For the cases of rotating-bending and ultrasonic axial cycling with R= -1.0, -0.5 and 0.5, the S-N curves are single-line type corresponding to the slip mechanism or cleavage mechanism. For the cases of R= -0.1 and 0.1,the S-N curves are bilinear type corresponding to both slip and cleavage mechanisms. A model based on fatigue life and fatigue limit is proposed to describe the competition between the two mechanisms, which is in agreement with the experimental results.

KeywordTi-6a1-4v Alloy Very-high-cycle Fatigue Microstructure Stress Ratio Slip Mechanism Cleavage Mechanism
DOI10.11900/0412.1961.2015.00581
Indexed BySCI ; EI ; CSCD
Language中文
WOS IDWOS:000381541900004
WOS KeywordTi-6A1-4V alloy ; very-high-cycle fatigue ; microstructure ; stress ratio ; slip mechanism ; cleavage mechanism
Funding OrganizationNational Natural Science Foundation of China 11202210 11572325
CSCD IDCSCD:5761349
DepartmentLNM金属材料微结构与力学性能
ClassificationQ3
Ranking1
Citation statistics
Cited Times:1[CSCD]   [CSCD Record]
Document Type期刊论文
Identifierhttp://dspace.imech.ac.cn/handle/311007/59798
Collection非线性力学国家重点实验室
Corresponding AuthorHong, YS
Recommended Citation
GB/T 7714
刘小龙,孙成奇,周砚田,等. 微结构和应力比对Ti-6A1-4V高周和超高周疲劳行为的影响[J]. 金属学报,2016,52(8):923-930.
APA 刘小龙,孙成奇,周砚田,洪友士,&Hong, YS.(2016).微结构和应力比对Ti-6A1-4V高周和超高周疲劳行为的影响.金属学报,52(8),923-930.
MLA 刘小龙,et al."微结构和应力比对Ti-6A1-4V高周和超高周疲劳行为的影响".金属学报 52.8(2016):923-930.
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