Probing the effect of intragranular premature κ-carbide on incipient plasticity behavior in austenite-based Fe-Mn-Al-(Cr)-C steels

Abstract

The effect of nanoscale intragranular premature κ-carbide precipitates, having an ordered structure but without chemical partitioning, on the incipient plasticity behavior of austenite in Fe-Mn-Al-(Cr)-C low-density steels was investigated by nanoindentation. We found that the incipient plasticity was dominated by a heterogeneous dislocation nucleation mechanism via atom-vacancy exchange. Although the content of κ-carbide decreased with Cr addition, its negligible effect on incipient plasticity strength was witnessed by the slightly increased shear stress for dislocation nucleation. Comparatively, the increased interstitial C atoms with Cr content in austenite enhanced lattice cohesions which impeded the nucleation events by increasing the requisite shear stress.

Keywords

• fe-mn-al-c low-density steel
• premature κ-carbide
• dislocation nucleation
• nanoindentation
• charge transfer