Improved Predictability of Microstructure Evolution during Hot Deformation of Titanium Alloys

Ricardo Henrique Buzolin*, Franz Miller Branco Ferraz, Michael Lasnik, Alfred Krumphals, M. C. Poletti

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Two different mesoscale models based on dislocation reactions are developed and applied to predict both the flow stress and the microstructure evolution during the hot deformation of titanium alloys. Three distinct populations of dislocations, named mobile, immobile, and wall dislocations, describe the microstructure, together with the crystal misorientation and the densities of boundaries. A simple model consisting of production and recovery terms for the evolution of dislocations is compared with a comprehensive model that describes the reactions between different type of dislocations. Constitutive equations connect the microstructure evolution with the flow stresses. Both models consider the formation of a high angle grain boundary by continuous dynamic recrystallization due to progressive lattice rotation. The wall dislocation density evolution is calculated as a result of the subgrain size and boundary misorientation distribution evolutions. The developed models are applied to two near-β titanium alloys, Ti-5553 and Ti-17, and validated for use in hot compression experiments. The differences in the predictability between the developed models are discussed for the flow stress, dislocation densities and microstructure evolutions. Only the comprehensive model can predict the different reactions and their contributions to the evolution of mobile and immobile dislocation densities. The comprehensive model also allows for correlating the elastic strain rate with the softening and hardening kinetics. Despite those differences, the selection of the model used has a small influence on the overall prediction of the subgrain size and the fraction of high angle grain boundaries.
Original languageEnglish
Article number5678
Pages (from-to)1-30
Number of pages30
JournalMaterials
Volume13
Issue number24
DOIs
Publication statusPublished - 12 Dec 2020

Keywords

  • mesoscale model
  • dislocation density
  • hot deformation
  • microstructure
  • Continuous dynamic recrystallization
  • Titanium alloys
  • Dislocation density
  • Hot deformation
  • Mesoscale model
  • Microstructure

ASJC Scopus subject areas

  • Metals and Alloys
  • Materials Science(all)

Fields of Expertise

  • Advanced Materials Science

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