The role played by deformation twinning and twin–twin intersections in the strain-hardening behavior of Hadfield steel single crystals was identified by using strain-field measurements. In situ and ex situ strain-field measurements resolved at micrometer length scales were obtained using digital image correlation. Ex situ measurements reveal that macroscopic twin-bands, which were composed of a mixture of fine twin-lamella and matrix material, generate approximately 30% axial strain. This measurement was comparable to strain predictions based on twinning crystallography. In situ measurements reveal that primary and secondary twins may nucleate simultaneously, but the primary twin-system remains predominantly active with increased deformation. The intersection of primary and secondary twin-systems was directly linked to an increase in the strain hardening response.

Strain Hardening and Heterogeneous Deformation during Twinning in Hadfield Steel. C.Efstathiou, H.Sehitoglu: Acta Materialia, 2010, 58[5], 1479-88