<p>A novel thermomechanical process is proposed, wherein intercritical warm rolling followed by varying cold rolling reductions is conducted prior to the identical annealing. The study investigates the resulting microstructural characteristics and their influence on the tensile behavior of δ-ferrite-containing medium-Mn steel. The alteration of cold rolling reductions from 0 to 60% results in significant microstructural variation in annealed samples, abbreviated as CRA0, CRA40, and CRA60. For instance, the combination of lath and equiaxed ferrite (α)-austenite (γ) microstructures in the CRA0 sample transforms to a more homogeneous structure with primarily equiaxed morphology. The δ-ferrite phase, on the other hand, remains as equiaxed morphology but shows a significant reduction in average grain size with cold rolling deformations. The overall recrystallization and elemental partitioning during annealing are attributed to these variations. Furthermore, the process yields the tensile strength &gt; 800&#xa0;MPa and ductility ranging from ~ 30 to ~ 58% without the presence of a yield point plateau, which is typically observed in cold-rolled samples. The observed tensile properties are mainly ascribed to the TRIP effect and HDI strengthening mechanisms operating during deformation. Variations in austenite stability lead to differences in the TRIP effect, while associated strain partitioning during deformation leads to different interface-affected zones and hence varying HDI strengthening. These combined factors govern the observed strength–ductility balance in the samples. In addition, phase-wise bulk texture analysis reveals a strong correlation with the TRIP effect and highlights the role of ferrite (α/δ) during tensile deformation.</p> Graphic abstract <p></p>