In order to improve the roll material and to prevent the breaking of the slabbing and heavy rougher mill rolls, the thermal fatigue test, rotating bending fatigue test, impact test, and tensile test were carried out for the conventional roll materials. The main results are as follows.
(I) Nickel-chromium cast steel (SNI) is superior to chromium cast steel (SCR) and ductile cast iron (DC) in the properties of toughness, thermal fatigue strength and fatigue notch sensitivity. It is appropriate to use the SNI steel as a roll material to prevent the breaking of the roll.
(2) The fatigue notch factors of the roll materials are smaller than 1.5
