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Title: Crystal Plasticity Model Validation Using Combined High-Energy Diffraction Microscopy Data for a Ti-7Al Specimen

High-Energy Diffraction Microscopy (HEDM) is a 3-d x-ray characterization method that is uniquely suited to measuring the evolving micromechanical state and microstructure of polycrystalline materials during in situ processing. The near-field and far-field configurations provide complementary information; orientation maps computed from the near-field measurements provide grain morphologies, while the high angular resolution of the far-field measurements provide intergranular strain tensors. The ability to measure these data during deformation in situ makes HEDM an ideal tool for validating micro-mechanical deformation models that make their predictions at the scale of individual grains. Crystal Plasticity Finite Element Models (CPFEM) are one such class of micro-mechanical models. While there have been extensive studies validating homogenized CPFEM response at a macroscopic level, a lack of detailed data measured at the level of the microstructure has hindered more stringent model validation efforts. We utilize an HEDM dataset from an alphatitanium alloy (Ti-7Al), collected at the Advanced Photon Source, Argonne National Laboratory, under in situ tensile deformation. The initial microstructure of the central slab of the gage section, measured via near-field HEDM, is used to inform a CPFEM model. The predicted intergranular stresses for 39 internal grains are then directly compared to data from 4 far-field measurementsmore » taken between ~4% and ~80% of the macroscopic yield strength. In conclusion, the intergranular stresses from the CPFEM model and far-field HEDM measurements up to incipient yield are shown to be in good agreement, and implications for application of such an integrated computational/experimental approach to phenomena such as fatigue and crack propagation is discussed.« less
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [4]
  1. Air Force Research Lab., Wright-Patterson AFB (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Air Force Research Lab., Wright-Patterson AFB (United States); Nutonian Inc., Somerville, MA (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
  5. Carnegie Mellon Univ., Pittsburgh, PA (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science
Additional Journal Information:
Journal Volume: 48; Journal Issue: 2; Journal ID: ISSN 1073-5623
Publisher:
ASM International
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Air Force Research Laboratory (AFRL), Materials and Manufacturing Directorate
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; three-dimensional microstructure; High Energy Diffraction Microscopy (HEDM); crystal plasticity finite element modeling (CPFEM); far field diffraction; near field diffraction; x-ray diffraction
OSTI Identifier:
1390797