Phase transformations, high-temperature mechanical properties of a tool steel as well as its structure before and after rolling were studied with the aim of clarifying why high-carbon highly-alloyed steels can be rolled with rather high degrees of deformation at moderately low temperatures (ϳ800°C). Three factors were found to bring the steel mechanical properties to the level that makes this type treatment possible. They are: 1) higher plasticity and lower strength of a-phase as compared with g-phase at the same temperature; 2) stability of the ferrite-carbide state up to temperatures exceeding 800°C; 3) plasticity induced by a→g transformation in the process of rolling.