The paper presents the results of research on the microstructure of GX2CrNiMoCuN25-6-3-3 and GX2CrNiMoCuN25-6-3 cast steels with
a varying carbon content. The cause for undertaking the research were technological problems with hot cracking in bulk castings of duplex
cast steel with a carbon content of approx. 0.06% and with 23% Cr, 8.5% Ni, 3% Mo and 2.4% Cu. The research has shown
a significant effect of increased carbon content on the ferrite and austenite microstructure morphology, while exceeding the carbon content
of 0.06% results in a change of the shape of primary grains from equiaxial to columnar.