On the hot deformation behavior of Ti-6Al-4V made by additive manufacturing

Markus Bambach, Irina Sizova*, Joanna Szyndler, Jennifer Bennett, Greg Hyatt, Jian Cao, Thomas Papke, Marion Merklein

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Innovative process chains that use additive manufacturing (AM) to produce pre-forms for hot forging have been proposed recently, but almost no scientific knowledge on the hot deformation behavior of AM material exists. The combination of AM and metal forming may allow for producing pre-forms by AM which can be forged to the final shape in a single forming operation, thus saving tooling costs compared to conventional multi-stage forging processes. In this work, Ti-6Al-4 V samples made from powder using Directed Energy Deposition (DED) and Selective Laser Melting (SLM) are investigated under typical hot working conditions. An increasing cooling rate in AM promotes the formation of martensite. When heated to forming temperature, the martensite decomposes and yields intermediate microstructures with improved hot working properties compared to conventional wrought material. Differences in the flow stress and activation energy for hot working are analyzed for conventional and as-built Ti-6Al-4 V. AM material exhibits both lower flow stresses and a faster globularization rate, which is explained by non-equilibrium phase fractions and the spatial arrangement of the β-phase. A model is proposed to predict flow stresses and microstructure evolution in Ti-6Al-4 V specimens with a conventional and AM microstructure, which takes the spatial arrangement into account. The findings can be used to design new process chains that allow for single-stage net-shape forging of Ti-6Al-4 V parts at reduced forming forces and with improved mechanical properties.

Original languageEnglish (US)
Article number116840
JournalJournal of Materials Processing Technology
Volume288
DOIs
StatePublished - Feb 2021

Keywords

  • Additive manufacturing
  • Hot deformation
  • Titanium

ASJC Scopus subject areas

  • Ceramics and Composites
  • Computer Science Applications
  • Metals and Alloys
  • Industrial and Manufacturing Engineering

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