A graphite-containing high-speed steel roll

Abstract

The invention discloses a graphite-containing high-speed steel roller and belongs to the field of mechanical casting. B and N chemical elements are introduced into traditional high-speed steel components; MC-type and / or M<2>C-type, and dot-shaped and / or blocky highly-hard alloy carbides, nitrides and borides with the total area percentage being 20-35% are dispersed and distributed in a matrix structure of a working layer; the two steps that firstly, carbide, nitride and boride modification treatment is performed, and then graphite modification inoculation treatment is performed are adopted, graphite is separated out of an original structure, therefore, the high-speed steel roller maintains the unique advantage of high temperature abrasion resistance of traditional high-speed steel, meanwhile, the problem of a large friction coefficient of original traditional high-speed steel rollers is solved, the abrasion resistance of high-speed steel is fully achieved, the lubrication effect between the roller and a workpiece during rolling is achieved, and therefore, occurrence of the steel-adhesion phenomenon is prevented; and besides, by means of heat-conducting property and lubricating property of graphite, the defects of thermal impact, hot cracking sensitivity, steel adhesion tendency and surface texturing tendency of the high-speed steel rollers can be overcome, and especially during usage for a finished product rack, the surface brightness of rolled products is improved remarkably.

Description

technical field [0001] The invention relates to a graphite-containing high-speed steel roll, which belongs to the field of mechanical casting. Background technique [0002] The alloy content of the outer layer (working layer) of the existing traditional high-speed steel roll is usually C 1.5-2.5, Si 0.2-0.8, Mn 0.4-0.8, P≤0.05, S≤0.02, Cr 4-6, Ni 0.6- 1.5, Mo 3-5, W 0-3, the metallographic structure of the outer layer does not contain graphite, and these alloy elements mainly exist in the form of carbides in the roll structure, and the proportion of carbides is usually 10-20% between. The proportion of granular alloy carbides is relatively low, and the proportion of matrix area is relatively large. Therefore, during the use of the roll, especially when it is used for the finish rolling product stand, the rolling temperature is low, and the rolling speed is high, the roll base is exposed to the rolling material passing through at low temperature and high speed and the entra...

AI Technical Summary

Problems solved by technology

Therefore, during the use of the roll, especially when it is used for the finish rolling product stand, the rolling temperature is low, and the rolling speed is high, the roll base is exposed to the rolling material passing through at low temperature and high speed and the entrainment on the surface of the rolling material. Under the friction of oxide scales, the matrix is ​​preferentially worn and the fulcrum of high-hard carbide is exposed on the surface of the roll, which is specifically manifested in the increase of the surface friction coefficient of the roll (pass type), the decrease of brightness (the phenomenon of roughening), and in severe cases There is steel sticking on the pass surface, which affects the surface quality of rolled products

As a result, the unique anti-wear performance of high-speed steel and the ability to maintain roll shape cannot be effectively exerted, resulting in early roll change

[0003] In addition, when the existing traditional high-speed steel rolls are used in the process of preparing the finished round bar frame with large specifications and high surface quality requirements, due to the deep pass, the inner groove bottom and the groove side of the roll pass The linear velocity difference in different radial directions leads to the relative solid slip (rheology) of the rolled material at the same section, and the huge solid slip produces a file force on the surface of the roll pass, resulting in slippage between the bottom and the side wall of the roll pass. The wrinkle texture is shifted, and the wear of the bottom of the groove is intensified, which affects the precision and surface quality of the rolled material, and cannot fully exert the wear-resistant characteristics of high-speed steel, resulting in early roll change

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