Steel base rolls have a carbon ratio ranging between 1,50 and 2,10% and are Cr-Ni-Mo alloyed. Chemical analysis and specific heat treatments give the material the high mechanical properties typical of steel and the wear resistance distinctive of cast iron. Hardness is constant in the whole working layer. The structure is made up of pearlic matrix and of small carbides. Graphitic steel rolls have a better thermal conductivity thanks to the presence of graphite nodules.