Ti-6Al-4V Additively Manufactured by Selective Laser Melting with Superior Mechanical Properties

W. Xu*, S. Sun, J. Elambasseril, Q. Liu, M. Brandt, M. Qian

*Corresponding author for this work

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

The Achilles’ heel of additively manufactured Ti-6Al-4V by selective laser melting (SLM) is its inferior mechanical properties compared with its wrought (forged) counterparts. Acicular α′ martensite resulted from rapid cooling by SLM is primarily responsible for high strength but inadequate tensile ductility achieved in the as-fabricated state. This study presents a solution to eliminating the adverse effect of the nonequilibrium α′ martensite. This is achieved by enabling in situ martensite decomposition into a novel ultrafine (200–300 nm) lamellar (α + β) microstructure via the selection of an array of processing variables including the layer thickness, energy density, and focal offset distance. The resulting tensile elongation reached 11.4% while the yield strength was kept above 1100 MPa. These properties compare favorably with those of mill-annealed Ti-6Al-4V consisting of globular α and β. The fatigue life of SLM-fabricated Ti-6Al-4V with an ultrafine lamellar (α + β) structure has approached that of the mill-annealed counterparts and is much superior to that of SLM-fabricated Ti-6Al-4V with α′ martensite.

Original languageEnglish
Pages (from-to)668-673
Number of pages6
JournalJOM
Volume67
Issue number3
DOIs
Publication statusPublished - Mar 2015
Externally publishedYes

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