Comprehensive study on the formation of grain boundary serrations in additively manufactured Haynes 230 alloy

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Maximilian Haack - , Fraunhofer Institute for Material and Beam Technology (Author)
  • Martin Kuczyk - , Fraunhofer Institute for Material and Beam Technology (Author)
  • André Seidel - , Fraunhofer Institute for Material and Beam Technology (Author)
  • Elena López - , Fraunhofer Institute for Material and Beam Technology (Author)
  • Frank Brueckner - , Institute of Materials Science, Fraunhofer Institute for Material and Beam Technology (Author)
  • Christoph Leyens - , Chair of Materials Technology, Fraunhofer Institute for Material and Beam Technology (Author)

Abstract

Recently, grain boundary serrations have been introduced in conventionally processed Haynes 230 through a slow-cooling heat treatment. The aim of this work was to utilize these heat treatments to introduce serrations in additively manufactured (Laser Metal Deposition) Haynes 230. Contrary to expectations, serrations already formed during the fast-cooling of the Laser Metal Deposition process. Electron Backscatter Diffraction was used to elucidate the underlying phenomenon for the emergence of serrations during fast-cooling. As a result, a hypothesis regarding a new mechanism responsible for the formation of grain boundary serrations was formulated. Additionally, specific characteristics of the Laser Metal Deposition process have been identified. This includes a columnar-to-equiaxed transition (CET) for slower feed rates, leading to smaller grains despite lower cooling rates; the observation of an abrupt increase in grain growth for a raised solution annealing temperature; the fact that serrations hinder uncontrolled grain growth and finally that the LMD-process leads to a finer carbide morphology compared to conventional manufacturing methods, potentially leading to an increased precipitation strengthening effect.

Details

Original languageEnglish
Article number110092
JournalMaterials characterization
Volume160
Publication statusPublished - Feb 2020
Peer-reviewedYes

External IDs

Scopus 85077398171

Keywords

Keywords

  • Additive manufacturing, EBSD, Grain boundary serration, Haynes 230, Laser metal deposition, Superalloy