Microstructure effects on fatigue crack growth in additively manufactured Ti–6Al–4V

Raeann VanSickle, David Foehring, Huck Beng Chew, John Lambros

Research output: Contribution to journalArticlepeer-review

Abstract

In this work we investigate the relationship between the different microstructural features in additively-manufactured (AM) Direct Metal Laser Deposited Ti–6Al–4V alloys and the observed fatigue and fracture behaviors, using high resolution Digital Image Correlation experiments and microstructural imaging. Fatigue cracks in the AM specimens were observed to periodically propagate parallel to the α' laths and deflect at prior β grain boundaries. Corresponding plastic strain distributions show needle-like regions of high strain that correlated to the α' laths, suggesting significant influence of the microstructure on the plastic zone. In many cases, the fatigue cracks also propagated towards voids from unsintered powder or gas entrapment in the vicinity. In several experiments, premature failure of the AM specimens occurred under monotonic fracture or cyclic fatigue loading, which we attribute to the presence of void clusters located near the crack-tip. These fatigue and fracture characteristics were similar for AM specimens of different build-orientations.

Original languageEnglish (US)
Article number139993
JournalMaterials Science and Engineering A
Volume795
DOIs
StatePublished - Sep 23 2020

Keywords

  • Additive manufacturing
  • Defects
  • Fatigue
  • Fracture
  • Microstructure
  • Plastic wake

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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