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Changzhou Wujin Guangyu Embossing Roller Machinery Co.,Ltd

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Hot Roller Hot Roll Roll Surface Damage Form

Hot Roller Hot roll roll surface damage in the form of 1, roller crack crack 2, indentation 3, oxide film off 4, sticky steel, abnormal wear and so on.

1, roll crack crack

The normal crack is also called hot crack, which is caused by the thermal stress caused by repeated temperature cycling. The surface of the roll is gradually broken, which is a kind of micro-surface layer which occurs on the roll surface. Normal cracks in the rolling process due to slipping, sticky steel, steel, heap steel, flick and other accidents caused by thermal shock cracks in the surface of the roller surface to form a certain depth and extension of the crack.

2, indentation

Hot Roller Mainly refers to the production process, due to cleaning and other causes of iron oxide skin and other foreign objects into the roller surface to produce continuous or discontinuous distribution of irregular shape of the pit and so on.

3, the oxide film off

Rolling began, after a period of time after the hot roll, the roll surface to form a layer of silver-gray or light blue thin oxide film, the protection of the roller surface, improve the surface quality of the rolling is very important, due to the repeated role of rolling force , Resulting in oxide film along the carbide around the micro-cracks; when the roll cooling capacity is insufficient, the roll surface is difficult to form a dense oxide film, even if the formation of oxide film will soon deteriorate. In the rolling is unreasonable, the oxide film in the process of rapid destruction, will cause the oxide film off, leaving a meteor spot on the roller surface defects, resulting in increased roll surface roughness, wear increased.

4, sticky steel, abnormal wear and so on

Hot Roller Due to the rolling caused by the roll surface and the rolling of the adhesion, the emergence of sticky steel; rolling process parameters unreasonable caused by the same width of the roll consumption is too large, resulting in uneven roller surface wear phenomenon.

Production, should be from the standardization of operations, equipment maintenance aspects to avoid the above aspects of roller surface damage occurred.

Selection of hot roll materials

In addition to ordinary chilled cast iron, there are low nickel chrome molybdenum, nickel chrome molybdenum, high nickel chrome molybdenum cast iron materials, high-grade chilled cast iron material for the high nickel Chrome molybdenum chilled cast iron. The drawback of this type of material roll is low hardness, wear resistance is not good. Later, the use of ductile iron cast iron roll, relatively speaking, the service life increased several times, is still in use. Foreign is generally used semi-steel and high hardness special semi-steel material, to overcome the surface roughness and anti-wear are very effective.

In order to improve the wear resistance of the hot roll, hot roll materials continue to be improved, the basic development process is from chilled cast iron to high chromium cast iron to semi-high speed steel and high speed steel.

Hot Roller The chemical composition of high chromium cast iron roll is 2.0% ~ 4.0% C, 10% ~ 30% Cr, 0.15% ~ 1.6% Ni, 0.3% ~ 2.9% Mo. Its essence is a high wear resistance of high alloy white iron, chromium content is generally 10% to 15%, the carbide is mainly M7C3 type, and white cast iron continuous M8C type carbide, it not only has Good wear resistance, and a higher hardness (HV up to 1800), the matrix is austenite, martensite, and therefore its hardness and toughness combined with better. The actual rolling production shows that the high chromium cast iron roll has good thermal cracking resistance because the roll surface produces a layer of dense and tough chromium oxide film, can reduce the number and depth of hot cracks. Therefore, the high-chromium cast iron roll in the 20th century, 80 years is very widely used in finishing the front frame. At present, high-chromium cast iron composite roll has been widely used as hot-rolled strip (steel) rolling mill, rough rolling and finishing the first section of the work roll, wide plate; roughing and finishing roll and small steel and bar rolling mill Wait.