Influence of Weld Pores on the Very Long-Life Fatigue Failure of the Electron Beam Welding Joints of TC17 Titanium Alloy

Fulin  Liu; Hong  Zhang; Hanqing  Liu; Yao  Chen; Kashif Khan; Qingyuan  Wang; Yongjie Liu

doi:10.3390/ma12111825

Influence of Weld Pores on the Very Long-Life Fatigue Failure of the Electron Beam Welding Joints of TC17 Titanium Alloy

Fulin Liu , Hong Zhang , Hanqing Liu , Yao Chen , Kashif Khan, Qingyuan Wang , Yongjie Liu

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Abstract

The electron beam welding process is widely used in the connection among titanium alloy material parts of aero-engines. Its mechanical properties need to meet the requirements of long life and high reliability. In this paper, the static strength and the fatigue failure behavior of the electron beam weldments of TC17 titanium alloy were investigated experimentally under low amplitude high frequency (20 kHz), and the mechanical response and failure mechanism under different external loading conditions were analyzed. In summary, the samples were found to have anisotropic microstructure. The tensile strength of the PWHT of TC17 EBW joint was~ 4.5% lower than that of the base metal. Meanwhile, compared with the base metal, the fatigue strength was reduced by 45.5% at 10 9 cycles of fatigue life. The fracture analysis showed that the fatigue failure of the welded joint of TC17 alloy was caused by the welded pores and the fatigue cracks initiated from the welded pores. A fine granular area (FGA) was observed around the crack initiation region. The existence of pores caused the stress intensity factor of the fine granular area (K FGA) to be inversely proportional to the fatigue life. The K FGA calculation formula was modified and the fatigue crack propagation threshold of the welded joint of TC17 alloy was calculated (3.62 MPa· m 1/2). Moreover, the influences of the effective size and the relative depth of the pores on the very long fatigue life of the electron beam welded joint of TC17 titanium alloy were discussed.

Original language	English
Pages (from-to)	1825
Number of pages	17
Journal	Materials
Volume	12
Issue number	11
DOIs	https://doi.org/10.3390/ma12111825
Publication status	Published - 5 Jun 2019

Bibliographical note

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Keywords

titanium alloy TC17
electron beam welded joint
welded pores
very high cycle fatigue regime
stress intensity factor

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10.3390/ma12111825

PublishedFinal published version, 12 MBLicence: CC BY

Kashif Khan
- Centre for Manufacturing and Materials - Assistant Professor Academic
Person: Teaching and Research

Cite this

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title = "Influence of Weld Pores on the Very Long-Life Fatigue Failure of the Electron Beam Welding Joints of TC17 Titanium Alloy",

abstract = "The electron beam welding process is widely used in the connection among titanium alloy material parts of aero-engines. Its mechanical properties need to meet the requirements of long life and high reliability. In this paper, the static strength and the fatigue failure behavior of the electron beam weldments of TC17 titanium alloy were investigated experimentally under low amplitude high frequency (20 kHz), and the mechanical response and failure mechanism under different external loading conditions were analyzed. In summary, the samples were found to have anisotropic microstructure. The tensile strength of the PWHT of TC17 EBW joint was~ 4.5% lower than that of the base metal. Meanwhile, compared with the base metal, the fatigue strength was reduced by 45.5% at 10 9 cycles of fatigue life. The fracture analysis showed that the fatigue failure of the welded joint of TC17 alloy was caused by the welded pores and the fatigue cracks initiated from the welded pores. A fine granular area (FGA) was observed around the crack initiation region. The existence of pores caused the stress intensity factor of the fine granular area (K FGA) to be inversely proportional to the fatigue life. The K FGA calculation formula was modified and the fatigue crack propagation threshold of the welded joint of TC17 alloy was calculated (3.62 MPa· m 1/2). Moreover, the influences of the effective size and the relative depth of the pores on the very long fatigue life of the electron beam welded joint of TC17 titanium alloy were discussed.",

keywords = "titanium alloy TC17, electron beam welded joint, welded pores, very high cycle fatigue regime, stress intensity factor",

author = "Fulin Liu and Hong Zhang and Hanqing Liu and Yao Chen and Kashif Khan and Qingyuan Wang and Yongjie Liu",

note = "This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.",

year = "2019",

month = jun,

day = "5",

doi = "10.3390/ma12111825",

language = "English",

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journal = "Materials",

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AU - Liu , Fulin

AU - Zhang , Hong

AU - Liu , Hanqing

AU - Chen , Yao

AU - Khan, Kashif

AU - Wang , Qingyuan

AU - Liu, Yongjie

N1 - This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PY - 2019/6/5

Y1 - 2019/6/5

N2 - The electron beam welding process is widely used in the connection among titanium alloy material parts of aero-engines. Its mechanical properties need to meet the requirements of long life and high reliability. In this paper, the static strength and the fatigue failure behavior of the electron beam weldments of TC17 titanium alloy were investigated experimentally under low amplitude high frequency (20 kHz), and the mechanical response and failure mechanism under different external loading conditions were analyzed. In summary, the samples were found to have anisotropic microstructure. The tensile strength of the PWHT of TC17 EBW joint was~ 4.5% lower than that of the base metal. Meanwhile, compared with the base metal, the fatigue strength was reduced by 45.5% at 10 9 cycles of fatigue life. The fracture analysis showed that the fatigue failure of the welded joint of TC17 alloy was caused by the welded pores and the fatigue cracks initiated from the welded pores. A fine granular area (FGA) was observed around the crack initiation region. The existence of pores caused the stress intensity factor of the fine granular area (K FGA) to be inversely proportional to the fatigue life. The K FGA calculation formula was modified and the fatigue crack propagation threshold of the welded joint of TC17 alloy was calculated (3.62 MPa· m 1/2). Moreover, the influences of the effective size and the relative depth of the pores on the very long fatigue life of the electron beam welded joint of TC17 titanium alloy were discussed.

AB - The electron beam welding process is widely used in the connection among titanium alloy material parts of aero-engines. Its mechanical properties need to meet the requirements of long life and high reliability. In this paper, the static strength and the fatigue failure behavior of the electron beam weldments of TC17 titanium alloy were investigated experimentally under low amplitude high frequency (20 kHz), and the mechanical response and failure mechanism under different external loading conditions were analyzed. In summary, the samples were found to have anisotropic microstructure. The tensile strength of the PWHT of TC17 EBW joint was~ 4.5% lower than that of the base metal. Meanwhile, compared with the base metal, the fatigue strength was reduced by 45.5% at 10 9 cycles of fatigue life. The fracture analysis showed that the fatigue failure of the welded joint of TC17 alloy was caused by the welded pores and the fatigue cracks initiated from the welded pores. A fine granular area (FGA) was observed around the crack initiation region. The existence of pores caused the stress intensity factor of the fine granular area (K FGA) to be inversely proportional to the fatigue life. The K FGA calculation formula was modified and the fatigue crack propagation threshold of the welded joint of TC17 alloy was calculated (3.62 MPa· m 1/2). Moreover, the influences of the effective size and the relative depth of the pores on the very long fatigue life of the electron beam welded joint of TC17 titanium alloy were discussed.

KW - titanium alloy TC17

KW - electron beam welded joint

KW - welded pores

KW - very high cycle fatigue regime

KW - stress intensity factor

U2 - 10.3390/ma12111825

DO - 10.3390/ma12111825

M3 - Article

SN - 1996-1944

VL - 12

SP - 1825

JO - Materials

JF - Materials

IS - 11

ER -

Influence of Weld Pores on the Very Long-Life Fatigue Failure of the Electron Beam Welding Joints of TC17 Titanium Alloy

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