On the deformation behavior of κ-carbide-free and κ-carbide-containing high-Mn light-weight steel

Light-weight high-manganese steels offer a high potential for industrial application due to their excellent combination of mechanical properties and reduced density. In the present work, the deformation behavior of an Fe-29.8Mn-7.65Al-1.11C steel was investigated by means of TEM microstructure analysis and XRD texture measurements. CALPHAD calculations were used to determine the processing parameters for the applied heat treatments in order to produce essentially different initial microstructures, i.e. single-phase austenite in homogenized condition with large grain size (state A), 2-phase steel composed of austenite and κ-carbides in aged condition with large grain size (state B), and single-phase austenite in recrystallized condition with fine grain size (state C). Since this is the first study to directly compare the plastic deformation of the same alloy with and without κ-carbides, the influence of the precipitation state could be successfully identified. Although the mechanical properties were strongly affected by grain size and precipitation state, the developed deformation microstructures and textures appeared very similar and evidenced the activation of the same deformation mechanisms in the material in states A, B, and C. The strong work hardening in these alloys was facilitated by planar dislocation glide leading to slip band refinement, i.e. Slip band Refinement-Induced Plasticity (SRIP) rather than microband formation. The reasons for this deformation behavior as well as its influence on the evolution of rolling and tensile textures are discussed.

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