Tailoring microstructure and mechanical properties of additively-manufactured ti6al4v using post processing

Yaron Itay Ganor, Eitan Tiferet, Sven C. Vogel, Donald W. Brown, Michael Chonin, Asaf Pesach, Amir Hajaj, Andrey Garkun, Shmuel Samuha, Roni Z. Shneck, Ori Yeheskel

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Additively-manufactured Ti-6Al-4V (Ti64) exhibits high strength but in some cases inferior elongation to those of conventionally manufactured materials. Post-processing of additively manufactured Ti64 components is investigated to modify the mechanical properties for specific applications while still utilizing the benefits of the additive manufacturing process. The mechanical properties and fatigue resistance of Ti64 samples made by electron beam melting were tested in the as-built state. Several heat treatments (up to 1000 °C) were performed to study their effect on the microstructure and mechanical properties. Phase content during heating was tested with high reliability by neutron diffraction at Los Alamos National Laboratory. Two different hot isostatic pressings (HIP) cycles were tested, one at low temperature (780 °C), the other is at the standard temperature (920 °C). The results show that lowering the HIP holding temperature retains the fine microstructure (~1% β phase) and the 0.2% proof stress of the as-built samples (1038 MPa), but gives rise to higher elongation (~14%) and better fatigue life. The material subjected to a higher HIP temperature had a coarser microstructure, more residual β phase (~2% difference), displayed slightly lower Vickers hardness (~15 HV10N), 0.2% proof stress (~60 MPa) and ultimate stresses (~40 MPa) than the material HIP’ed at 780 °C, but had superior elongation (~6%) and fatigue resistance. Heat treatment at 1000 °C entirely altered the microstructure (~7% β phase), yield elongation of 13.7% but decrease the 0.2% proof-stress to 927 MPa. The results of the HIP at 780 °C imply it would be beneficial to lower the standard ASTM HIP temperature for Ti6Al4V additively manufactured by electron beam melting.

Original languageEnglish
Article number658
Pages (from-to)1-17
Number of pages17
JournalMaterials
Volume14
Issue number3
DOIs
StatePublished - 1 Feb 2021

Keywords

  • Electron beam melting
  • Fatigue
  • HIP
  • Mechanical properties
  • Microstructure
  • Neutron diffraction
  • Ti-6Al-4V

ASJC Scopus subject areas

  • Materials Science (all)
  • Condensed Matter Physics

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