The performance and quality of a roll generally depend 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 difference are:
(1) Mill conditions
Such as rolling mill type, rolling mill, and roll design, pass design, water cooling conditions, and bearing types;
(2) Rolling conditions
Such as the variety, specifications, and deformation resistance of rolling materials, reduction system, and temperature system, output requirements and operations, etc.;
(3) Requirements for product quality and surface quality, etc.
Therefore, different types of rolling mills and the same type of rolling mills with different use conditions have different requirements for the performance of the rolls used, such as billet and slab blooming mill rolls should have good torsional and bending strength, toughness, bite, Thermal cracking resistance and thermal shock resistance and wear resistance; while the hot strip finishing stand requires high hardness, indentation resistance, wear resistance, spalling resistance and thermal crack resistance of the roll surface.
Only by understanding the conditions of use of the rolls and the failure mode of the rolls used in the same type of rolling mill, and understanding the performance and manufacturing process of the current various roll materials, can the technical conditions of the rolls for the rolling mill be more correctly formulated and suitable and economical.
The methods most commonly used to evaluate roll performance in rolling mills are:
(1) Roll weight (kg) (referred to as roll consumption) consumed by rolling 1t of rolled material, expressed in kg/t;
(2) The weight of the rolled material is reduced per unit roll diameter, expressed in t/mm.
With the modernization of rolling mills, in-depth research on the failure of rolls in use, and improvements in roll materials and manufacturing processes, the average roll consumption in industrially developed countries has been reduced to below 1kg/t.