Materials World Network: Physically based approach for predicting and minimizing damage nucleation in metals

• Applicant: Professor Dr.-Ing. Philip Eisenlohr, Ph.D.
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 43577365

• Final Report Year: 2012

Final Report Abstract

With commercial purity titanium as model material (hexagonal lattice structure, limited ductility) and four-point bending of samples with a moderately preferred crystallographic orientation and grain sizes of the order of 50–100 µm we investigated the deformation response on the surface that is loaded in tension. By utilizing atomic force microscopy, orientation imaging microscopy, and 3D X-ray analysis in combination, we were able to obtain quantitative details of the amount of slip that occurred in local neighborhoods (comprising about a dozen grains each) as well as an indication of the three-dimensional structure of the investigated grain patch and its subsurface slip activity. One relevant outcome was the identification of a geometric relationship that results in a high chance for localized deformation - either in the form of slip bands or mechanical twins - to penetrate through a grain boundary into the neighboring grain. The experimental data on deformation activity can be directly compared with crystal plasticity finite element simulations, and the existing (local) model taking into account dislocation slip and mechanical twinning in a phenomenological fashion has some success in predicting heterogeneous deformation of the microstructure. Accurate modeling of heterogeneous deformation is a necessary foundation upon which to evaluate and develop credible models for damage nucleation in the future, and indeed this was the focus of our follow-on proposal that was just funded for continuing this collaborative effort.

Publications

• Strain Heterogeneity and Damage Nucleation at Grain Boundaries during Monotonic Deformation in Commercial Purity Titanium. JOM, 61(12):45–52, 2009. ISSN 1047-4838
  T.R. Bieler, M.A. Crimp, Y. Yang, L. Wang, P. Eisenlohr, D.E. Mason, W. Liu, and G.E. Ice
  
• The role of heterogeneous deformation on damage nucleation at grain boundaries in single phase metals. Int. J. Plast., 25(9):1655–1683, 2009
  T.R. Bieler, P. Eisenlohr, F. Roters, D. Kumar, D.E. Mason, M.A. Crimp, and D. Raabe
  
• Nucleation of paired twins at grain boundaries in titanium. Scripta Mater., 63:827–830, 2010
  L. Wang, P. Eisenlohr, Y. Yang, T.R. Bieler, and M.A. Crimp
  
• Overview of constitutive laws, kinematics, homogenization, and multiscale methods in crystal plasticity finite element modeling: theory, experiments, applications. Acta Materialia, 58:1152–1211, 2010
  F. Roters, P. Eisenlohr, L. Hantcherli, D.D. Tjahjanto, T.R. Bieler, and D. Raabe
  
• Twin Nucleation by Slip Transfer across Grain Boundaries in Commercial Purity Titanium. Metall. Mater. Trans. A, 41(2):421– 430, 2010
  L. Wang, Y. Yang, P. Eisenlohr, T.R. Bieler, M.A. Crimp, and D.E. Mason
  
• A dislocation density-based crystal plasticity constitutive model for prismatic slip in α-titanium. Acta Materialia, 59(18):7003–7009, 2011. ISSN 1359-6454
  A. Alankar, P. Eisenlohr, and D. Raabe
  
• Experimental Characterization and Crystal Plasticity Modeling of Heterogeneous Deformation in Polycrystalline α-Ti. Metall. Mater. Trans. A, 42(3):626–635, 2011
  L. Wang, R.I. Barabash, Y. Yang, T.R. Bieler, M.A. Crimp, P. Eisenlohr, W. Liu, and G.E. Ice
  
• Quantitative Atomic Force Microscopy Characterization and Crystal Plasticity Finite Element Modeling of Heterogeneous Deformation in Commercial Purity Titanium. Metall. Mater. Trans. A, 42(3):636–644, 2011
  Y. Yang, L. Wang, T. Bieler, P. Eisenlohr, and M. Crimp