Commonly used roll materials and uses are shown in the table. The performance and quality of a roll generally depends on its chemical composition and manufacturing method and can be assessed by its structure, physical and mechanical properties, and the type of residual stress present inside the roll (see roll inspection). The use effect of the roll in the rolling mill depends not only on the material of the roll and its metallurgical quality, but also on the conditions of use, roll design, operation and maintenance. The operating conditions of the rolls of different types of rolling mills are very different, and the factors that cause the differences are: (1) rolling mill conditions. Such as rolling mill type, rolling mill and roll design, pass design, water cooling conditions and bearing types, etc.; (2) rolling conditions such as rolling material varieties, specifications and their deformation resistance, reduction system and temperature system, output requirements and operations, etc.; (3) Requirements for product quality and surface quality, etc.