The formation mechanism, influencing factors and processing control of stray grains in nickel-based single crystal superalloys

Yafeng Li, Lin Liu, Taiwen Huang, Dejian Sun, Jun Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

16 Scopus citations

Abstract

The thermal profile of a directionally solidifying nickel-based single crystal (SX) turbine blade was simulated using a Procast finite element technique. The result showed that the local thermal profile in the platform is wave-shaped rather than a planar or consistent concave. Such a distributed thermal profile forms an isolated thermal undercooling zone in the platform end and affects the dendritic branching process into the platform region. Based on the thermal and grain growth analyses, the criterion of stray grain formation was proposed as a competition process on the time of the dendritic branching from the airfoil to the platform end and the cooling of the platform end to the heterogeneous nucleation temperature. The influencing factors, namely the withdrawal rate, the directional solidification method, the platform dimension, the alloy composition and the crystal orientation on stray grain formation were then systematically investigated according to the criterion. Several stray grain (SG) controlling techniques with different mechanisms were proposed and analyzed based on the thermal evolution process.

Original languageEnglish
Title of host publicationSUPERALLOYS 2016 - Proceedings of the 13th International Symposium on Superalloys
EditorsMark Hardy, Eric Huron, Uwe Glatzel, Brian Griffin, Beth Lewis, Cathie Rae, Venkat Seetharaman, Sammy Tin
PublisherMinerals, Metals and Materials Society
Pages293-301
Number of pages9
ISBN (Electronic)9781118996669
DOIs
StatePublished - 2016
Event13th International Symposium on Superalloys, SUPERALLOYS 2016 - Seven Springs, United States
Duration: 11 Sep 201615 Sep 2016

Publication series

NameProceedings of the International Symposium on Superalloys
Volume2016-January

Conference

Conference13th International Symposium on Superalloys, SUPERALLOYS 2016
Country/TerritoryUnited States
CitySeven Springs
Period11/09/1615/09/16

Keywords

  • Control methods
  • Directional solidification
  • Influencing factors
  • Mechanism
  • Single crystal
  • Stray grain

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