Hot Roll is mainly cast iron roll and cast steel roll. Cast Iron Roll is divided into nodular cast iron, chilled cast iron, infinitely chilled cast iron, cast steel is divided into 70Mn, 70Mn2,70MN2MO, 75CrMo, 140CrNiMo, 160CrNiMo and other materials. The performance and quality of the roll depend on its chemical composition and manufacturing method, and the use effect of the roll in the mill is also related to the use condition and operation and maintenance. Therefore, different types of mills and mills of the same type with different operating conditions require different roll properties, such as cogging mill roll to have a good twist and bending strength, toughness, bite human nature, hot cracking resistance and thermal shock resistance and wear resistance; The finishing stand of hot strip mill requires the roll surface to have high hardness, anti-indentation, wear-resisting, anti-spalling and anti-heat cracking properties. Therefore, it is necessary to understand the working conditions of rollers and the failure modes of such rollers, as well as the properties and manufacturing processes of various materials of rollers, to select suitable and economical roll materials and to formulate the technical conditions of rolls correctly.