Quantitatively evaluating the huge Luders band deformation in an ultrafine grain stainless steel by combining in situ neutron diffraction and digital image correlation analysis

In the present study, a hybrid in situ neutron diffraction and digital image correlation measurement was per-formed on tensile deformation of an ultrafine grain (UFG) stainless steel exhibiting a huge Luders band defor-mation to evaluate the individual contribution of the austenite matrix and the deformation-induced martensite to the strain hardening during the propagation of the band. Quantitative analysis revealed that the strain hardening of the austenite matrix was insufficient to maintain a uniform deformation when the flow stress was greatly enhanced by the UFG structure. The strain hardening required for the Luders band to propagate was mostly provided by the formation of martensite and the high internal stress within it.

Automated summary

In this study, an in-situ neutron diffraction and digital image correlation measurement were conducted on an ultrafine grain stainless steel with a large Luders band deformation to assess the individual contributions of the austenite matrix and deformation-induced martensite to strain hardening during band propagation. The quantitive analysis revealed that the strain hardening of the austenite matrix was insufficient to maintain uniform deformation when the flow stress increased due to the ultrafine grain structure. The strain hardening required for Luders band propagation was primarily provided by martensite formation and the high internal stress within it.