Predicting failure modes and ductility of dual phase steels using plastic strain localization

X. Sun, K. S. Choi, W. N. Liu, M. A. Khaleel

Research output: Contribution to journalArticle

241 Citations (Scopus)

Abstract

Ductile failure of metals is often treated as the result of void nucleation, growth and coalescence. Various criteria have been proposed to capture this failure mechanism for various materials. In this study, ductile failure of dual phase steels is predicted in the form of plastic strain localization resulting from the incompatible deformation between the harder martensite phase and the softer ferrite matrix. Microstructure-level inhomogeneity serves as the initial imperfection triggering the instability in the form of plastic strain localization during the deformation process. Failure modes and ultimate ductility of two dual phase steels are analyzed using finite element analyses based on the actual steel microstructures. The plastic work hardening properties for the constituent phases are determined by the in-situ synchrotron-based high-energy X-ray diffraction technique. Under different loading conditions, different failure modes and ultimate ductility are predicted in the form of plastic strain localization. It is found that the local failure mode and ultimate ductility of dual phase steels are closely related to the stress state in the material. Under plane stress condition with free lateral boundary, one dominant shear band develops and leads to final failure of the material. However, if the lateral boundary is constrained, splitting failure perpendicular to the loading direction is predicted with much reduced ductility. On the other hand, under plane strain loading condition, commonly observed necking phenomenon is predicted which leads to the final failure of the material. These predictions are in reasonably good agreement with experimental observations.

Original languageEnglish
Pages (from-to)1888-1909
Number of pages22
JournalInternational Journal of Plasticity
Volume25
Issue number10
DOIs
Publication statusPublished - 1 Oct 2009
Externally publishedYes

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Keywords

  • Dual phase steel
  • Ductile fracture
  • Failure mode
  • Micromechanical model
  • Microstructure

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Materials Science(all)

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