Please wait a minute...
Acta Metall Sin  2016, Vol. 52 Issue (8): 923-930    DOI: 10.11900/0412.1961.2015.00581
Orginal Article Current Issue | Archive | Adv Search |
EFFECTS OF MICROSTRUCTURE AND STRESS RATIO ON HIGH-CYCLE AND VERY-HIGH-CYCLE FATIGUE BEHAVIOR OF Ti-6Al-4V ALLOY
Xiaolong LIU1,Chengqi SUN1,Yantian ZHOU2,Youshi HONG1()
1 State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China 。
2 Heat Treatment Plant, Wafangdian Bearing Co. Ltd., Dalian 116300, China
Download:  HTML  PDF(1553KB) 
Export:  BibTeX | EndNote (RIS)      
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 1010 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-6Al-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-6Al-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.

Key words:  Ti-6Al-4V alloy      very-high-cycle fatigue      microstructure      stress ratio      slip mechanism      cleavage mechanism     
Received:  12 November 2015     
Fund: Supported by National Natural Science Foundation of China (Nos.11202210 and 11572325)

Cite this article: 

Xiaolong LIU,Chengqi SUN,Yantian ZHOU,Youshi HONG. EFFECTS OF MICROSTRUCTURE AND STRESS RATIO ON HIGH-CYCLE AND VERY-HIGH-CYCLE FATIGUE BEHAVIOR OF Ti-6Al-4V ALLOY. Acta Metall Sin, 2016, 52(8): 923-930.

URL: 

https://www.ams.org.cn/EN/10.11900/0412.1961.2015.00581     OR     https://www.ams.org.cn/EN/Y2016/V52/I8/923

Fig.1  Schematics of shape and dimensions of specimens (unit: mm, R—stress ratio)

(a) rotating bending (b) ultrasonic, R= -1.0 (c) ultrasonic, R>-1.0=2.26×107 cyc)

Fig.2  SEM images of Ti-6Al-4V alloy after annealing (700 ℃, 2 h, A.C.) (a) and solution-ageing (920 ℃, 1 h, A.C. + 550 ℃, 4 h, A.C.) (b) heat-treatments (αp—primary α grain, ββ grain, αs—secondary α grain)
Fig.3  EBSD results of Ti-6Al-4V alloy after annealing (a) and solution-ageing (b) heat-treatments
Fig.4  Fatigue crack initiation by slip mechanism (σa—fatigue strength, Nf—fatigue life)

(a) fully-equiaxed microstructure (rotating bending, σa=620 MPa, Nf=4.38×107 cyc)(b) bimodal microstructure (rotating bending, σa=690 MPa, Nf=2.47×105 cyc)

Fig.5  Fatigue crack initiation by cleavage mechanism (arrows show the facets)

(a) fully-equiaxed microstructure (axial loading at R=0.1, σa=339 MPa, Nf=3.09×107 cyc) (b) bimodal microstructure (axial loading at R=0.1, σa=339 MPa, Nf=2.26×107 cyc)

Fig.6  Schematic of interior crack initiation (a) and morphologies of facet (b), rough area (c) and fish-eye (d) by AFM (bimodal microstructure, axial loading at R=0.1, σa=250 MPa, Nf=2.02×107 cyc)
Fig.7  Morphology of cleavage facet (a) and EDS result of facet (b) (bimodal microstructure, axial loading at R=0.1, σa=339 MPa, Nf
Fig.8  Distributions of facet size and primary α grain size
Fig.9  S-N curves of Ti-6Al-4V alloy under rotating bending (R.B.—rotating bending, Sli—fatigue induced by slip mechanism, symbol with arrow—unbroken) (a) fully-equiaxed microstructure (b) bimodal microstructure
Fig.10  S-N curves of Ti-6Al-4V alloy under ultrasonic axial loading (Cle—fatigue induced by cleavage mechanism, symbol with arrow—unbroken) (a) fully-equiaxed microstructure (b) bimodal microstructure
Fig.11  Relation between lgD* and stress amplitude at different stress ratios
Fig.12  Schematic of competition between slip mechanism and cleavage mechanism
[1] Li S X.Int Mater Rev, 2012; 57: 92
[2] Hong Y S, Zhao A G, Qian G A.Acta Metall Sin, 2009; 45: 769
[2] (洪友士, 赵爱国, 钱桂安. 金属学报, 2009; 45: 769)
[3] Liu X L, Sun C Q, Hong Y S.Mater Sci Eng, 2015; A622: 228
[4] Leopold G, Nadot Y, Billaudeau T, Mendez J.Fatigue Fract Eng Mater Struct, 2015; 38: 1026
[5] Ding H S, Shang Z B, Wang Y Z, Chen R R, Guo J J, Fu H Z.Acta Metall Sin, 2015; 51: 569
[5] (丁宏升, 尚子博, 王永喆, 陈瑞润, 郭景杰, 傅恒志. 金属学报, 2015; 51: 569)
[6] Neal F D, Blenkinsop P A.Acta Metall, 1976; 24: 59
[7] Szczepanski C J, Jha S K, Larsen J M, Jones J W.Metall Mater Trans, 2008; 39A: 2841
[8] Chandran K S, Jha S K.Acta Mater, 2005; 53: 1867
[9] Chandran K S, Chang P, Cashman G T.Int J Fatigue, 2010; 32: 482
[10] Oguma H, Nakamura T.Int J Fatigue, 2013; 50: 89
[11] Oguma H, Nakamura T.Scr Mater, 2010; 63: 32
[12] Chandran K S.Nat Mater, 2005; 4: 303
[13] Shanyavskiy A A.Sci China-Phys Mech Astron, 2014; 57: 19
[14] Lei Z Q, Xie J J, Sun C Q, Hong Y S.Sci China-Phys Mech Astron, 2014; 57: 74
[15] Matsunaga H, Sun C, Hong Y, Murakami Y.Fatigue Fract Eng Mater Struct, 2015; 38: 1274
[16] Goodman J.Mechanics Applied Engineering. London: Longman, Green and Co Ltd, 1899: 30
[17] Gerber W. Z Bayer Archit Ing Ver, 1874; 6: 101
[18] Zuo J H, Wang Z G, Han E-H.Mater Sci Eng, 2008; A473: 147
[19] Takeuchi E, Furuya Y, Nagashima N, Matsuoka S.Tetsu Hagané, 2010; 96: 36
[19] (竹内悦男, 古谷佳之, 長島伸夫, 松岡三郎.鉄と鋼, 2010; 96: 36)
[20] Takeuchi E, Furuya Y, Nagashima N, Matsuoka S.Fatigue Fract Eng Mater Struct, 2008; 31: 599
[21] Morrissey R, Nicholas T.Int J Fatigue, 2006; 28: 1577
[22] Basquin O H.Proc Astm, 1910; 10: 625
[23] Sun C, Lei Z, Hong Y.Mech Mater, 2014; 69: 227
[24] Qian G A, Zhou C E, Hong Y S.Acta Mater, 2011; 59: 1321
[25] Hong Y S, Zhao A G, Qian G A, Zhou C E.Metall Mater Trans, 2012; 43A: 2753
[1] HUANG Yuan, DU Jinlong, WANG Zumin. Progress in Research on the Alloying of Binary Immiscible Metals[J]. 金属学报, 2020, 56(6): 801-820.
[2] YU Jiaying, WANG Hua, ZHENG Weisen, HE Yanlin, WU Yurui, LI Lin. Effect of the Interface Microstructure of Hot-Dip Galvanizing High-Strength Automobile Steel on Its Tensile Fracture Behaviors[J]. 金属学报, 2020, 56(6): 863-873.
[3] GENG Yaoxiang, FAN Shimin, JIAN Jianglin, XU Shu, ZHANG Zhijie, JU Hongbo, YU Lihua, XU Junhua. Mechanical Properties of AlSiMg Alloy Specifically Designed for Selective Laser Melting[J]. 金属学报, 2020, 56(6): 821-830.
[4] LIU Zhenpeng, YAN Zhiqiao, CHEN Feng, WANG Shuncheng, LONG Ying, WU Yixiong. Fabrication and Performance Characterization of Cu-10Sn-xNi Alloy for Diamond Tools[J]. 金属学报, 2020, 56(5): 760-768.
[5] ZHAO Yanchun, MAO Xuejing, LI Wensheng, SUN Hao, LI Chunling, ZHAO Pengbiao, KOU Shengzhong, Liaw Peter K.. Microstructure and Corrosion Behavior of Fe-15Mn-5Si-14Cr-0.2C Amorphous Steel[J]. 金属学报, 2020, 56(5): 715-722.
[6] LI Xiucheng,SUN Mingyu,ZHAO Jingxiao,WANG Xuelin,SHANG Chengjia. Quantitative Crystallographic Characterization of Boundaries in Ferrite-Bainite/Martensite Dual-Phase Steels[J]. 金属学报, 2020, 56(4): 653-660.
[7] YANG Ke,SHI Xianbo,YAN Wei,ZENG Yunpeng,SHAN Yiyin,REN Yi. Novel Cu-Bearing Pipeline Steels: A New Strategy to Improve Resistance to Microbiologically Influenced Corrosion for Pipeline Steels[J]. 金属学报, 2020, 56(4): 385-399.
[8] QIAN Yue,SUN Rongrong,ZHANG Wenhuai,YAO Meiyi,ZHANG Jinlong,ZHOU Bangxin,QIU Yunlong,YANG Jian,CHENG Guoguang,DONG Jianxin. Effect of Nb on Microstructure and Corrosion Resistance of Fe22Cr5Al3Mo Alloy[J]. 金属学报, 2020, 56(3): 321-332.
[9] XIAO Hong,XU Pengpeng,QI Zichen,WU Zonghe,ZHAO Yunpeng. Preparation of Steel/Aluminum Laminated Composites by Differential Temperature Rolling with Induction Heating[J]. 金属学报, 2020, 56(2): 231-239.
[10] CHENG Chao,CHEN Zhiyong,QIN Xushan,LIU Jianrong,WANG Qingjiang. Microstructure, Texture and Mechanical Property ofTA32 Titanium Alloy Thick Plate[J]. 金属学报, 2020, 56(2): 193-202.
[11] DENG Congkun,JIANG Hongxiang,ZHAO Jiuzhou,HE Jie,ZHAO Lei. Study on the Solidification of Ag-Ni Monotectic Alloy[J]. 金属学报, 2020, 56(2): 212-220.
[12] WANG Tao,WAN Zhipeng,LI Zhao,LI Peihuan,LI Xinxu,WEI Kang,ZHANG Yong. Effect of Heat Treatment Parameters on Microstructure and Hot Workability of As-Cast Fine Grain Ingot of GH4720Li Alloy[J]. 金属学报, 2020, 56(2): 182-192.
[13] JIANG He,DONG Jianxin,ZHANG Maicang,YAO Zhihao,YANG Jing. Stress Relaxation Mechanism for Typical Nickel-Based Superalloys Under Service Condition[J]. 金属学报, 2019, 55(9): 1211-1220.
[14] ZHANG Beijiang,HUANG Shuo,ZHANG Wenyun,TIAN Qiang,CHEN Shifu. Recent Development of Nickel-Based Disc Alloys andCorresponding Cast-Wrought Processing Techniques[J]. 金属学报, 2019, 55(9): 1095-1114.
[15] Jinyao MA,Jin WANG,Yunsong ZHAO,Jian ZHANG,Yuefei ZHANG,Jixue LI,Ze ZHANG. Investigation of In Situ 1150 High Temperature Deformation Behavior and Fracture Mechanism of a Second Generation Single Crystal Superalloy[J]. 金属学报, 2019, 55(8): 987-996.
No Suggested Reading articles found!