Metallurgical and Materials Transactions A

, 41:421

Twin Nucleation by Slip Transfer across Grain Boundaries in Commercial Purity Titanium

Authors

  • L. Wang
    • Chemical Engineering and Materials Science DepartmentMichigan State University
  • Y. Yang
    • Chemical Engineering and Materials Science DepartmentMichigan State University
  • P. Eisenlohr
    • Max-Planck-Institut für Eisenforschung
    • Chemical Engineering and Materials Science DepartmentMichigan State University
  • M.A. Crimp
    • Chemical Engineering and Materials Science DepartmentMichigan State University
  • D.E. Mason
    • Mathematics and Computer Science DepartmentAlbion College
Article

DOI: 10.1007/s11661-009-0097-6

Cite this article as:
Wang, L., Yang, Y., Eisenlohr, P. et al. Metall and Mat Trans A (2010) 41: 421. doi:10.1007/s11661-009-0097-6

Abstract

The role of strain transfer in the activation of deformation twinning at grain boundaries has been characterized in commercially pure titanium deformed in bending. Two different orientations of a textured polycrystal were deformed in bending and were analyzed using electron backscattered diffraction (EBSD) to determine the active slip and twinning systems in the surface tensile region. Prismatic slip and \( \left\{ {10\bar{1}2} \right\}\left\langle {\bar{1}011} \right\rangle \) twinning were the most widely observed deformation modes in both orientations. Nonprismatic slip systems were also activated, most likely to accommodate local strain heterogeneities. A slip-stimulated twin nucleation mechanism was identified for soft/hard grain pairs: dislocation slip in a soft-oriented grain can stimulate twin nucleation in the neighboring hard grain when the slip system is well aligned with the twinning system. This alignment was described by a slip-transfer parameter m′.[24] Twins activated by this mechanism always had the highest m′ value among the six available \( \left\{ {10\bar{1}2} \right\}\left\langle {\bar{1}011} \right\rangle \) twinning systems, while the Schmid factor, based on the global (uniaxial tensile) stress state, was a less significant indicator of twin activity. Through slip transfer, deformation twins sometimes formed despite having a very low global Schmid factor. The frequency of slip-stimulated twin nucleation depends strongly on the texture and loading direction in the material. For grain pairs having one grain with a large Schmid factor for twinning, nonparametric statistical analysis confirms that those with a larger m′ are more likely to display slip-stimulated twinning.

Copyright information

© The Minerals, Metals & Materials Society and ASM International 2009