Strain hardening behavior of aluminum alloyed Hadfield steel single crystals

Very high strain hardening coefficients (=G/23) are observed for aluminum-alloyed face-centered cubic Hadfield steel single crystals under tensile loading. Alloying with aluminum suppressed deformation twinning in two of the three crystallographic orientations studied, and transmission electron microscopy results revealed the existence of dense dislocation walls (sheets) along crystallographic directions that form barriers to slip deformation. A visco-plastic self-consistent algorithm was modified to account for the interaction between the active slip systems and the high density dislocation walls, producing close prediction of the experimental strain hardening response. The model predicted the added hardening in single crystals deformed along [(1) over bar 1 1], [0 0 1] compared to the [(1) over bar 2 3] orientation, the increase in volume fraction of the dislocation walls with increased deformation and the role of twinning in the [1 2 3] orientation. (c) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.