High-chromium-steel supporting roller and preparing method thereof

Abstract

The invention discloses a high-chromium-steel supporting roller and a preparing method thereof. The method includes: a first step of material preparation, namely a step of preparing outer layer high-chromium molten steel of the supporting roller and center globular graphite molten iron of the supporting roller; a step of centrifugal pressure casting, namely a step of performing centrifugal pressure casting by adoption of a centrifugal roller mold, with the inner diameter of the centrifugal roller mold being 560-900 mm, maintaining the temperature (for a period of time), and unpacking to obtain a supporting roller workblank; and a step of subjecting the supporting roller workblank to thermal processing. By addition of V and Nb which are alloy elements to the outer layer casting molten steel, surface hardness of the supporting roller is uniform (not more than 1.0 / 1.5 degree), and can reach 50-65 HSD according to demands of users. By adding a BaCa nucleating agent improving the balling degree into the center globular graphite molten iron, the tensile strength of a roller neck is not less than 550 MPa. Accordingly, the high-chromium-steel supporting roller is extremely high in abrasion resistance and high in toughness and thermal fatigue resistance, and the accidents of fatigue cracks, peeling and falling on both sides of the roller body during operation of the supporting roller are almost avoided.

Description

technical field [0001] The invention relates to a high chromium steel support roll and a preparation method thereof. Background technique [0002] Back-up rolls used in domestic and foreign hot-rolled narrow-strip steel and medium and wide-band four-high finishing mills are restricted by factors such as high pressure on the band width and thin strip (below 2mm). The wear resistance of the steel is very poor. When rolling 450-600 tons, the roll surface will produce fine fatigue thermal cracks due to heat, calendering force, and roll stress. As the amount of rolling increases, the cracks will extend and expand, which will have a great impact on the production of strip steel and the cost will remain high; use alloy ductile iron or semi-steel to support the roll, due to the combination of carbon and other alloying elements in the matrix structure Carbide exists in the form of strips or nets. During the rolling operation, affected by heat, calendering force, impact force and the...

AI Technical Summary

Problems solved by technology

[0002] Back-up rolls used in domestic and foreign hot-rolled narrow-strip steel and medium and wide-band four-high finishing mills are restricted by factors such as high pressure on the band width and thin strip (below 2mm). The wear resistance is very poor. When rolling 450-600 tons, the roll surface will produce fine fatigue thermal cracks due to heat, calendering force, and roll stress.

As the amount of rolling increases, the cracks will extend and expand, which will have a great impact on the production of strip steel and the cost will remain high; use alloy ductile iron or semi-steel to support the roll, due to the combination of carbon and other alloying elements in the matrix structure Carbide exists in the form of strips or nets. During the rolling operation, affected by heat, calendering force, impact force and thermal stress of the roll, the back-up roll body is not squeezed by the circumferential direction and the horizontal direction of the steel on both sides of the steel. Compression, thermal fatigue cracks caused by concentrated stress, spalling and other phenomena, in severe cases, large areas of blocks will be dropped, which will have a greater impact on strip production and make the service life of the back-up roll prematurely invalid, so the loss is great. Rolling The strip surface quality does not meet the requirements

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