Microscale drivers and mechanisms of fracture in post-processed additively manufactured Ti–6Al–4V

Lara Draelos-Hagerty, Peeyush Nandwana, Ankit Srivastava

Research output: Contribution to journalArticlepeer-review

Abstract

Herein, we focus on understanding the microstructure-fracture correlations in a Ti–6Al–4V alloy additively manufactured via electron beam melting (EBM) and subjected to various post-process heat-treatments. Specifically, the as fabricated material is subjected to a sub-transus heat-treatment followed by air-cooling and a super-transus heat-treatment followed by either air- or furnace-cooling. Next, a series of in-situ single edge notch tension (SENT) tests are carried out under a high-resolution digital optical microscope. The panoramic high-resolution images captured during the in-situ tests are then used to characterize the planar deformation on the specimen surface using microstructure-based digital image correlation (DIC). The results of the in-situ SENT tests together with DIC and post-mortem fractographic analyses provided us with a better understanding of the microstructure-fracture correlations in these materials. Our results show that the fracture mechanism of the as fabricated and sub-transus heat-treated materials is essentially the same, while the changes in the microstructure following the super-transus heat-treatments significantly affects the fracture mechanism. In this case, several microcracks of hundreds of microns in length first nucleate away from the deformed notch following extreme plastic deformation at discrete locations. Furthermore, the location of these microcracks in the super-transus heat-treated materials is extremely sensitive to the details of the underlying microstructure.

Original languageEnglish
Pages (from-to)207-225
Number of pages19
JournalInternational Journal of Fracture
Volume242
Issue number2
DOIs
StatePublished - Aug 2023

Funding

The financial support provided by the Haythornthwaite Foundation through the ASME/AMD – Haythornthwaite Research Initiation Grant and the U.S. National Science Foundation grant CMMI-1944496 are gratefully acknowledged. The financial support provided by the Haythornthwaite Foundation through the ASME/AMD – Haythornthwaite Research Initiation Grant and the U.S. National Science Foundation grant CMMI-1944496 are gratefully acknowledged.

Keywords

  • Additive manufacturing
  • Crack nucleation
  • Digital image correlation
  • Fracture mechanism
  • In-situ fracture test
  • Titanium alloys

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