Phase composition, texture and residual stresses in steels with 1.6 and 2.9% Mn after hardening and cold rolling

The influence of composition and cold rolling on the structure and properties of steels with 1.6 and 2.9 Mn was evaluated using X-ray diffraction analysis of phase composition, texture, and residual stresses, as well as tensile testing. It was shown that after quenching from 1100°C, in addition to the α-phase, the steel with 1.6 Mn contains 4.7% and 2.5% of γ- and ε-phases, respectively. These phases transform into α-phase after cold rolling with a reduction of 20%. In the steel with 2.9 Mn, the amount of γ-phase after quenching was 49%, which decreases to 20% after a reduction of 20%, 12% after 40%, and 10% after 60 and 80%. In both steels, with increasing reduction, the reflections corresponding to the components of the rolling texture of BCC metals (200) and (222) intensify. In the steel with 2.9 Mn, a single-component texture of γ-phase of the «brass» type {110}<112> is formed. In the steel with 2.9 Mn at reductions of 20 and 40%, compressive stresses are formed due to the increase in volume during the γ→α transformation. Increasing the reduction during cold rolling leads to an increase in the yield strength of both steels, while the strength level of the steel with 1.6 Mn is significantly higher than that of the steel with 2.9 Mn. The relative elongation at reductions less than 40% correlates with the amount of deformation-unstable γ-phase.