Effects of size, geometry, and testing temperature on additively manufactured Ti-6Al-4V titanium alloy

Daniel June, Jason R. Mayeur, Paul Gradl, Andrew Wessman, Kavan Hazeli

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

This article presents a comprehensive study concerning size and geometry effect on the ambient and high-temperature mechanical behavior of additively manufactured laser powder bed fusion Ti-6Al-4V alloy. Key mechanical property metrics are presented, including strain hardening rate, yield strength, and Young's modulus as a function of thickness and testing temperature (ambient, 250 °C, and 450 °C). The effect of specimen size on manufacturing-induced microstructural feature formation is demonstrated and discussed. A detailed analysis regarding Young's modulus, yield strength, and strain hardening rate variation at elevated temperatures is also presented. Size effect and temperature-sensitive deformation mechanisms are linked to the underlying microstructural deformation mechanisms activated at respective temperatures. Counter-intuitively, this study determined that irrespective of the geometry, strain hardening rates increased as temperature increased. An in-depth microstructural examination is presented to explain the stated observation. The texture of Interrupted tensile test samples examined for ambient, 250 °C, and 450 °C post-yield was observed to be unchanged, indicating the strain hardening behavior was not texture dependent. Schmid factor analysis, coupled with experimental findings from previous work, was implemented to generate a hypothesis. This hypothesis suggests that the drop in critical resolved shear stress for basal and pyramidal slip systems, as temperature increases, paired with the high dislocation density of laser powder bed fusion Ti-6Al-4V, leads to dislocation entanglement and results in increased strain hardening at elevated temperatures.

Original languageEnglish
Article number103970
JournalAdditive Manufacturing
Volume80
DOIs
StatePublished - Jan 25 2024

Funding

Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). The NASA Marshall Space Flight Center, USA supported this investigation under Award Number: 80NSSC21M0319. The authors would like to thank Gabriel Demeneghi at NASA Marshal Space Flight Center and Mehrdad Pourjam at The University of Arizona for their input and discussion during this investigation.

FundersFunder number
U.S. Department of Energy
National Aeronautics and Space Administration
Marshall Space Flight Center80NSSC21M0319

    Keywords

    • Deformation mechanisms
    • High-temperature behavior
    • Size effect
    • Strain hardening rate
    • Ti alloys

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