The carbon content of cast iron rolls is about 2.5% -3.5%. According to the main material, they can be divided into four categories: ordinary cast iron rolls, high nickel chromium infinitely cold hard composite cast iron rolls, high chromium composite cast iron rolls, and alloy ductile iron rollers. The common structures in cast iron rolls can be divided into three categories: matrix, cementite, and graphite. The matrix structure mainly consists of martensite, ferrite, pearlite, bainite, and martensite. Graphite in cast iron generally has two forms: flake and spherical:

1. Ordinary cast iron roll

Ordinary cast iron rollers can be divided into cold hard cast iron rollers, medium and low alloy infinitely cold hard cast iron rollers, medium and low alloy ductile iron rollers. Cold hard cast iron is a type of cast iron obtained by using the undercooling degree of molten iron itself and the surface quenching of the mold. The surface of the roller body is quenched to form a white layer, which has high hardness and good wear resistance. Cold hard cast iron rollers can be divided into three categories based on manufacturing process and core material: non ductile iron, ductile composite, and spherical core. Infinite cold hard cast iron roller is a material between cold hard cast iron and gray cast iron. There is graphite in the matrix structure of the working layer of the roller body, and there is no clear boundary between the working layer of the roller body and the core. Rubber roller is this low-end roller. Ordinary cast iron rollers are mainly used for laminating thin plate mills, three roll Lauter plate mills, wire mills, bar mills, and section steel mills.

2. High nickel chromium infinite cold hard composite cast iron roll

Infinite cold hard cast iron is a material that lies between cold hard cast iron and gray cast iron. The working layer of the infinite cold hard cast iron roller body contains uniformly distributed graphite in the matrix structure. The content of graphite increases from the surface of the roller body to the inside with increasing depth, and the hardness decreases accordingly. Therefore, there is no clear boundary between the working layer of the roller body and the core, also known as unbounded cold hard cast iron roller. Infinite cold hard cast iron roller material contains high chromium When nickel and molybdenum alloy elements are used, high nickel chromium infinite cold hard cast iron rollers are produced using full flushing (overflow method) or centrifugal composite casting process.

3. High chromium composite cast iron roll

High chromium composite cast iron rollers are produced using high chromium white wear-resistant cast iron with a chromium content of 12-22% as the outer layer material of the roller body. Generally, ductile iron is used as the core and neck material of the roller, and centrifugal composite casting technology is used to produce high alloy composite cast iron rollers. High chromium cast iron rollers have excellent wear resistance and are widely used as working rolls in the front section of roughing and finishing mills for hot rolled strip mills, working rolls for roughing and finishing mills for wide, medium and thick plate mills, and finishing mills for small section and plate mills.

4. Alloy ductile iron roll

Alloy nodular cast iron rollers have high tensile strength, can withstand heavy loads, and have good wear resistance due to the uniform distribution of graphite from the roller body to the core in a spherical shape. The matrix structure is composed of carbides and pearlite or needle like bodies. Alloy nodular cast iron rollers can be generally divided into two categories based on the matrix structure of the roller body: pearlite nodular cast iron rollers and needle like nodular cast iron rollers. Alloy nodular cast iron rollers are generally cast as a whole, but needle like cast iron rollers can use centrifugal composite casting technology due to their high alloy content and high casting stress to achieve ideal comprehensive performance.