High-performance high-speed steel has high wear resistance and hardenability, especially the red hardness at high temperature, which makes high-performance high-speed steel more suitable for manufacturing rolls and roll rings.
Therefore, high-speed steel rolls are not only suitable for plate and strip mills, but also for wire and bar mills, and have achieved remarkable results.
Chemical properties
Physical properties
Material characteristics
The high-speed steel roll ring is a steel-based roll ring, which implements the national cast steel roll standard GB/T1503-2008. Its main alloy components are vanadium, nickel, tungsten, molybdenum, niobium, cobalt, and other elements, the carbon content is less than 1.6%, and the phosphorus content must be controlled below 0.03%, the chromium content must be less than 5%, and the sulfur content must be controlled below 0.03%.
This fully guarantees the material’s high wear resistance and impact toughness, and at the same time ensures that the roll ring will not be used during use. The phenomenon of micro cracks, falling blocks, and ring explosions appear. In particular, the content of tungsten is strictly controlled, and segregation will not occur during centrifugal casting, so the hardness drop after each re-grinding is small, and the amount of steel passing will not be significantly reduced.
Manufacturing process
Process design review→tooling design→modeling→smelting→centrifugal casting→heat preservation→unpacking→flaw detection→heat treatment after rough machining→flaw detection→hardness testing→semi-finishing and corresponding testing→finishing and flaw detection→metallographic testing→factory inspection→wrap up and store.
All roll rings are inspected 3 times one by one to ensure the inner quality of the mill rolls, and are tempered three times to obtain a good metallographic structure to ensure good product performance.
The outer layer of the roll contains relatively high Cr, Mo, W, V, Ni, and Nb elements, and the matrix structure is martensite + MC type carbide. The organization has extremely high abrasion resistance, good thermal crack resistance, and bite resistance. The hardness of the working layer can reach 80-90HSD, and the hardness drop is less than 1HSD. The use of HSS rolls can greatly reduce the number of grinding, reduce roll consumption, and improve the surface quality of the rolled material. have a broad vision of application.
- High-speed steel rolls have high carbon content and high alloying elements such as tungsten, molybdenum, vanadium, chromium, niobium, etc. Therefore, the types of carbides in the roll structure are mainly MC type and M2C type, and the carbide hardness is high and has good wear resistance.
- The HSS roller has good thermal stability and the roll surface has high hardness and good wear resistance at the rolling temperature.
- The high-speed steel rolls and rings have good hardenability, and the hardness from the surface of the roll body to the inside of the working layer is almost not reduced, so as to ensure that the roll has the same good wear resistance from the inside to the outside.
- During the use of the roll, under good cooling conditions, a thin and dense oxide film is formed on the surface of the roll body. This uniform, thin and dense oxide mold exists for a long time without falling off, making the high-speed steel roll wear-resistant Significantly increased.
- The formation of an oxidation mold on the surface of the HSSmill rolls during rolling reduces the friction between the rolled material and the roll surface. Therefore, it is easy to cause slippage during the rolling process, which makes the adjustment of the rolling mill more difficult.
- The high-speed steel material has a large expansion coefficient and good thermal conductivity. It is easy to cause roll shape deformation during rolling and affect the accuracy of the rolled material. Therefore, when the high-speed steel roll is used on the plate and strip rolling mill, not only the cooling system design must be changed, but also Also change the design of the roll shape.
- Since the core of the HSSrolling rings is made of alloy ductile iron, graphite steel, or forged steel, the roll diameter is high in strength.
- Because the high-speed steel material has good wear resistance, but the ability to resist accidents is poor, the effect of the use of high-speed steel rolls depends not only on the quality of the high-speed steel mill roll itself but also more importantly on the use conditions and maintenance of the roll.
Benefit
- Increased Productivity: HSS mill rolls are designed to have a longer service life than traditional casting mill rolls, reducing downtime for maintenance and replacement, resulting in higher output and reduced production costs.
- Improved Quality: HSS mill rolls have superior wear resistance, thermal conductivity, can reduce defects and improve surface finish for steel wire, resulting in higher customer satisfaction.
- Reduced Total Cost of Ownership: HSS mill rolls have ability to maintain shape and properties for extended periods of use enable them to handle higher loads and rolling speeds, which ultimately translates to improved profits for the manufacturer.
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