Mechanical behavior assessment of ti‐6al‐4v eli alloy produced by laser powder bed fusion

Asif Mahmud, Thinh Huynh, Le Zhou, Holden Hyer, Abhishek Mehta, Daniel D. Imholte, Nicolas E. Woolstenhulme, Daniel M. Wachs, Yongho Sohn

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

The present work correlates the quasi‐static, tensile mechanical properties of additively manufactured Ti‐6Al‐4V extra low interstitial (ELI, Grade 23) alloy to the phase constituents, microstructure, and fracture surface characteristics that changed with post‐heat treatment of stress relief (670 °C for 5 h) and hot isostatic pressing (HIP with 100 MPa at 920 °C for 2 h under an Ar atmosphere). Ti‐6Al‐4V ELI alloy tensile specimens in both the horizontal (i.e., X and Y) and vertical (Z) directions were produced by the laser powder bed fusion (LPBF) technique. Higher yield strength (1141 MPa), higher tensile strength (1190 MPa), but lower elongation at fracture (6.9%), along with mechanical anisotropy were observed for as‐stress‐relieved (ASR) samples. However, after HIP, consistent and isotropic mechanical behaviors were observed with a slight reduction in yield strength (928 MPa) and tensile strength (1003 MPa), but with a significant improvement in elongation at fracture (16.1%). Phase constituents of acicular α′ phase in ASR and lamellar α + β phases in HIP samples were observed and quantified to corroborate the reduction in strength and increase in ductility. The anisotropic variation in elongation at fracture observed for the ASR samples, particularly built in the build (Z) direction, was related to the presence of “keyhole” porosity.

Original languageEnglish
Article number1671
JournalMetals
Volume11
Issue number11
DOIs
StatePublished - Nov 2021

Funding

Funding: This research was sponsored by the Battelle Energy Alliances, LLC under contract no. DE‐ AC07‐05ID14517‐214376 with collaboration from the authors of the Idaho National Laboratory. The views, opinions, and conclusions made in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Battelle Energy

Keywords

  • Hot isostatic pressing
  • Laser powder bed fusion
  • Phase transformations
  • Titanium alloy

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