Criticality of porosity defects on the fatigue performance of wire + arc additive manufactured titanium alloy

Romali Biswal; Xiang Zhang; Abdul Syed; Mustafa Awd; Jialuo Ding; Frank Walther; Stewart Williams

doi:10.1016/j.ijfatigue.2019.01.017

Criticality of porosity defects on the fatigue performance of wire + arc additive manufactured titanium alloy

Romali Biswal, Xiang Zhang, Abdul Syed, Mustafa Awd, Jialuo Ding, Frank Walther, Stewart Williams

Research output: Contribution to journal › Article › peer-review

146 Citations (Scopus)

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Abstract

This study was aimed at investigating the effect of internal porosity on the fatigue strength of wire + arc additive manufactured titanium alloy (WAAM Ti-6Al-4V). Unlike similar titanium alloys built by the powder bed fusion processes, WAAM Ti-6Al-4V seldom contains gas pores. However, feedstock may get contaminated that may cause pores of considerable size in the built materials. Two types of specimens were tested: (1) control group without porosity referred to as reference specimens; (2) designed porosity group using contaminated wires to build the specimen gauge section, referred to as porosity specimens. Test results have shown that static strength of the two groups was comparable, but the elongation in porosity group was reduced by 60% and its fatigue strength was 33% lower than the control group. The stress intensity factor range of the crack initiating pore calculated by Murakami’s approach has provided good correlation with the fatigue life. The kink point on the data fitting curve corresponds well with the threshold value of the stress intensity factor range found in the literature. For predicting the fatigue limit, a modified Kitagawa-Takahashi diagram was proposed consisting of three regions depending on porosity size. Critical pore diameter was found to be about 100 µm.

Original language	English
Pages (from-to)	208-217
Number of pages	10
Journal	International Journal of Fatigue
Volume	122
Early online date	28 Jan 2019
DOIs	https://doi.org/10.1016/j.ijfatigue.2019.01.017
Publication status	Published - May 2019

Bibliographical note

NOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Fatigue. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Fatigue, [122], (2019] DOI: 10.1016/j.ijfatigue.2019.01.017

© 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

Keywords

Additive manufacturing
Kitagawa-Takahashi diagram
Porosity defects
Stress intensity factor
Ti-6Al-4V

ASJC Scopus subject areas

Modelling and Simulation
Materials Science(all)
Mechanics of Materials
Mechanical Engineering
Industrial and Manufacturing Engineering

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10.1016/j.ijfatigue.2019.01.017

Post-PrintAccepted author manuscript, 2.99 MBLicence: CC BY-NC-ND

Cite this

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title = "Criticality of porosity defects on the fatigue performance of wire + arc additive manufactured titanium alloy",

abstract = "This study was aimed at investigating the effect of internal porosity on the fatigue strength of wire + arc additive manufactured titanium alloy (WAAM Ti-6Al-4V). Unlike similar titanium alloys built by the powder bed fusion processes, WAAM Ti-6Al-4V seldom contains gas pores. However, feedstock may get contaminated that may cause pores of considerable size in the built materials. Two types of specimens were tested: (1) control group without porosity referred to as reference specimens; (2) designed porosity group using contaminated wires to build the specimen gauge section, referred to as porosity specimens. Test results have shown that static strength of the two groups was comparable, but the elongation in porosity group was reduced by 60% and its fatigue strength was 33% lower than the control group. The stress intensity factor range of the crack initiating pore calculated by Murakami{\textquoteright}s approach has provided good correlation with the fatigue life. The kink point on the data fitting curve corresponds well with the threshold value of the stress intensity factor range found in the literature. For predicting the fatigue limit, a modified Kitagawa-Takahashi diagram was proposed consisting of three regions depending on porosity size. Critical pore diameter was found to be about 100 µm.",

keywords = "Additive manufacturing, Kitagawa-Takahashi diagram, Porosity defects, Stress intensity factor, Ti-6Al-4V",

author = "Romali Biswal and Xiang Zhang and Abdul Syed and Mustafa Awd and Jialuo Ding and Frank Walther and Stewart Williams",

note = "NOTICE: this is the author{\textquoteright}s version of a work that was accepted for publication in International Journal of Fatigue. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Fatigue, [122], (2019] DOI: 10.1016/j.ijfatigue.2019.01.017 {\textcopyright} 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ ",

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AU - Biswal, Romali

AU - Zhang, Xiang

AU - Syed, Abdul

AU - Awd, Mustafa

AU - Ding, Jialuo

AU - Walther, Frank

AU - Williams, Stewart

N1 - NOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Fatigue. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Fatigue, [122], (2019] DOI: 10.1016/j.ijfatigue.2019.01.017 © 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

PY - 2019/5

Y1 - 2019/5

N2 - This study was aimed at investigating the effect of internal porosity on the fatigue strength of wire + arc additive manufactured titanium alloy (WAAM Ti-6Al-4V). Unlike similar titanium alloys built by the powder bed fusion processes, WAAM Ti-6Al-4V seldom contains gas pores. However, feedstock may get contaminated that may cause pores of considerable size in the built materials. Two types of specimens were tested: (1) control group without porosity referred to as reference specimens; (2) designed porosity group using contaminated wires to build the specimen gauge section, referred to as porosity specimens. Test results have shown that static strength of the two groups was comparable, but the elongation in porosity group was reduced by 60% and its fatigue strength was 33% lower than the control group. The stress intensity factor range of the crack initiating pore calculated by Murakami’s approach has provided good correlation with the fatigue life. The kink point on the data fitting curve corresponds well with the threshold value of the stress intensity factor range found in the literature. For predicting the fatigue limit, a modified Kitagawa-Takahashi diagram was proposed consisting of three regions depending on porosity size. Critical pore diameter was found to be about 100 µm.

AB - This study was aimed at investigating the effect of internal porosity on the fatigue strength of wire + arc additive manufactured titanium alloy (WAAM Ti-6Al-4V). Unlike similar titanium alloys built by the powder bed fusion processes, WAAM Ti-6Al-4V seldom contains gas pores. However, feedstock may get contaminated that may cause pores of considerable size in the built materials. Two types of specimens were tested: (1) control group without porosity referred to as reference specimens; (2) designed porosity group using contaminated wires to build the specimen gauge section, referred to as porosity specimens. Test results have shown that static strength of the two groups was comparable, but the elongation in porosity group was reduced by 60% and its fatigue strength was 33% lower than the control group. The stress intensity factor range of the crack initiating pore calculated by Murakami’s approach has provided good correlation with the fatigue life. The kink point on the data fitting curve corresponds well with the threshold value of the stress intensity factor range found in the literature. For predicting the fatigue limit, a modified Kitagawa-Takahashi diagram was proposed consisting of three regions depending on porosity size. Critical pore diameter was found to be about 100 µm.

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VL - 122

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EP - 217

JO - International Journal of Fatigue

JF - International Journal of Fatigue

ER -

Criticality of porosity defects on the fatigue performance of wire + arc additive manufactured titanium alloy

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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Xiang Zhang

Cite this

Criticality of porosity defects on the fatigue performance of wire + arc additive manufactured titanium alloy

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Profiles

Xiang Zhang

Cite this

Criticality of porosity defects on the fatigue performance of wire + arc additive manufactured titanium alloy