Two ingots weighing 400 g and 5 kg with nominal compositions of Fe–8Mn–4Al–2Si–0.5C–0.07V–0.05Sn were produced to investigate the effect of processing variables on microstructure development. The larger casting has a cooling rate more representative of commercial production and provides an understanding of the potential challenges arising from casting-related segregation during efforts to scale up medium Mn steels, while the smaller casting has a high cooling rate and different segregation pattern. Sections from both ingots were homogenized at 1250 $$^{\circ} $$
∘
C for various times to study the degree of chemical homogeneity and $$\delta $$
δ
-ferrite dissolution. Within 2 hours, the Mn segregation range (max–min) decreased from 8.0 to 1.7 wt pct in the 400 g ingot and from 6.2 to 1.5 wt pct in the 5 kg ingot. Some $$\delta $$
δ
-ferrite also remained untransformed after 2 hours in both ingots but with the 5 kg ingot showing nearly three times more than the 400 g ingot. Micress modeling was carried out, and good agreement was seen between predicted and measured segregation levels and distribution. After thermomechanical processing, it was found that the coarse untransformed $$\delta $$
δ
-ferrite in the 5 kg ingot turned into coarse $$\delta $$
δ
-ferrite stringers in the finished product, resulting in a slight decrease in yield strength. Nevertheless, rolled strips from both ingots showed $$>900$$
>
900
MPa yield strength, $$>1100$$
>
1100
MPa tensile strength, and $$>40$$
>
40
pct elongation with $$<10$$
<
10
pct difference in strength and no change in ductility when compared to a fully homogenized sample.