Microstructure and mechanical properties of long Ti-6Al-4V rods additively manufactured by selective electron beam melting out of a deep powder bed and the effect of subsequent hot isostatic pressing

Lu, S. L., Tang, H. P., Ning, Y. P., Liu, N., StJohn, D. H. and Qian, M. (2015) Microstructure and mechanical properties of long Ti-6Al-4V rods additively manufactured by selective electron beam melting out of a deep powder bed and the effect of subsequent hot isostatic pressing. Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 46 9: 3824-3834. doi:10.1007/s11661-015-2976-3


Author Lu, S. L.
Tang, H. P.
Ning, Y. P.
Liu, N.
StJohn, D. H.
Qian, M.
Title Microstructure and mechanical properties of long Ti-6Al-4V rods additively manufactured by selective electron beam melting out of a deep powder bed and the effect of subsequent hot isostatic pressing
Journal name Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science   Check publisher's open access policy
ISSN 1073-5623
1543-1940
Publication date 2015
Year available 2015
Sub-type Article (original research)
DOI 10.1007/s11661-015-2976-3
Open Access Status Not Open Access
Volume 46
Issue 9
Start page 3824
End page 3834
Total pages 11
Place of publication New York, NY, United States
Publisher Springer New York
Collection year 2016
Language eng
Abstract An array of eight long Ti-6Al-4V rods (diameter: 12 mm; height: 300 mm) have been additively manufactured, vertically and perpendicular to the powder bed, by selective electron beam melting (SEBM). The purpose was to identify and understand the challenges of fabricating Ti-6Al-4V samples or parts from a deep powder bed (more than 200-mm deep) by SEBM and the necessity of applying post heat treatment. The resulting microstructure and mechanical properties of these Ti-6Al-4V rods were characterized along their building (i.e., axial) direction by dividing each rod into three segments (top, middle, and bottom), both before (i.e., as-built) and after hot isostatic pressing (HIP). The as-built microstructure of each rod was inhomogeneous; it was coarsest in the top segment, which showed a near equilibrium α-β lamellar structure, and finest in the bottom segment, which featured a non-equilibrium mixed structure. The tensile properties varied along the rod axis, especially the ductility, but all tensile properties met the requirements specified by ASTM F3001-14. HIP increased the relative density from 99.03 pct of the theoretical density (TD) to 99.90 pct TD and homogenized the microstructure thereby leading to highly consistent tensile properties along the rod axis. The temperature of the stainless steel substrate used in the powder bed was monitored. The as-built inhomogeneous microstructure is attributed to the temperature gradient in the deep powder bed. Post heat treatment is thus necessary for Ti-6Al-4V samples or parts manufactured from a deep powder bed by SEBM. This differs from the additive manufacturing of small samples or parts from a shallow powder bed (less than 100-mm deep) by SEBM.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Online ahead of print

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mechanical & Mining Engineering Publications
Official 2016 Collection
 
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Citation counts: TR Web of Science Citation Count  Cited 9 times in Thomson Reuters Web of Science Article | Citations
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