What kinds of cast iron rolls are commonly used?

In China's current standards, cast iron rolls are divided into four categories: chilled cast iron rolls, infinite chilled cast iron rolls, nodular cast iron rolls and high chromium cast iron rolls. Because of the differences in composition, inoculation, cooling rate and heat treatment, cast iron has formed a huge system. Various cast iron rolls have different arrangement structures and functions and can be used in different rolling mills. Next, Wuxi Taihu roll Co., Ltd. will introduce cast iron rolls.

Residual stress and thermal stress will occur in the preparation process before making and application of cast iron roll. When used, it is further subjected to the effects of various periodic stresses, including twists and turns, changes, shear, contact stress and thermal stress.

Cast iron roll has good chip sedimentation, excellent cooling and cleanliness, and reduces scratches on the surface of the roll. Select the appropriate type of grinding wheel and grinding process parameters to ensure that the roll summarizes the problems, external vibration marks, transverse thread marks, external scratches, etc. It will not happen during grinding. Corundum grinding wheel is generally used for small and medium-sized centrifugal rolls. According to the raw materials of small and medium-sized centrifugal rolls, matching corundum grinding wheel can achieve higher surface quality and grinding accuracy. Generally, the problem of roll profile is mainly caused by the soft grinding wheel.

(1) The working layer of chilled cast iron roll is arranged as matrix plus carbon compound, and the center is arranged as gray iron. The transition orientation (i.e. transition layer) is clearly discernible on the fracture surface. Punching cast iron roll is famous for wear resistance. According to different grades, the hardness of chilled cast iron roll can reach 55 ~ 85hsd.

(2) The working layer of infinite chilled cast iron roll is arranged as the matrix with carbon compound and fine flake graphite, and the center is arranged as gray iron. There is a gradual transition (the transition layer is very wide), and there is no clear direction on the fracture. Due to the emergence of, the lower limit of hardness is lower than that of chilled cast iron roll, but after adding alloy, the hardness can also reach HSD. The hardness transition of infinitely chilled cast iron roll is smooth and the function of hot crack resistance is good.

(3) Nodular cast iron roll because of the spheroidizing effect of magnesium or rare earth elements on carbon, the arrangement of nodular cast iron roll is matrix plus spherical graphite, and there are varying amounts of carbon compounds in the working layer. The hardness scale of nodular cast iron roll is very wide, up to 42 ~ 80hsd. The nodular cast iron roll with acicular matrix can be obtained by relying on alloy elements and heat treatment, so that the hardness can reach 55 ~ 80hsd. The semi chilled nodular cast iron roll can also be made by using the method of metal mold sand lining. The hardness is reduced to 35 ~ 55hsd, and there is no significant drop to the center, so as to meet the needs of L ~ roll.

(4) The eutectic carbide m3c in the general arrangement of high chromium cast iron roll forms a continuous phase, so it is brittle. The eutectic carbide M7 C3 in high chromium cast iron forms intermittent phase, which reduces brittleness and improves resistance. With the difference of chromium layer and heat treatment process, the hardness scale of high chromium cast iron roll is very wide, which is 55 ~ 95hsd.

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