A Dislocation-Based Theory for the Deformation Hardening Behavior of DP Steels: Impact of Martensite Content and Ferrite Grain Size

Abstract

A dislocation model, accurately describing the uniaxial plastic stress-strain behavior of dual phase (DP) steels, is proposed and the impact of martensite content and ferrite grain size in four commercially produced DP steels is analyzed. It is assumed that the plastic deformation process is localized to the ferrite. This is taken into account by introducing a nonhomogeneity parameter, f(ε), that specifies the volume fraction of ferrite taking active part in the plastic deformation process. It is found that the larger the martensite content the smaller the initial volume fraction of active ferrite which yields a higher initial deformation hardening rate. This explains the high energy absorbing capacity of DP steels with high volume fractions of martensite. Further, the effect of ferrite grain size strengthening in DP steels is important. The flow stress grain size sensitivity for DP steels is observed to be 7 times larger than that for single phase ferrite.

Measuring Plasticity with Orientation Contrast Microscopy in Aluminium 6061-T4

“…Ignoring the simplifications of this model, it can be observed that the slope of this curve is positive but with descending second derivative, just as the predicted evolutions by theoretical dislocation balance equations [18,19].…”

Microstructural and Micromechanical Effects of Cold Roll-forming on High Strength Dual Phase Steels

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“…Bergström et al (2010). A uniaxial tensile test usually forms the basis of the characterisation, either directly from experimental data or by an analytical expression fitted to this data.…”