A steel rail with surface decarburization layer less than 0.3mm

Abstract

The invention provides a steel rail with a surface decarburized layer smaller than 0.3mm and a manufacturing method of the steel rail. The steel rail comprises the following chemical components in percentage by weight: 0.60-0.66% of C, 0.10-0.30% of Si, 0.8-1.2% of Mn, 0.2-0.5% of Cr, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 0.0002% of hydrogen, less than or equal to 0.0020% of oxygen and the balance of Fe and unavoidable impurities. The manufacturing method comprises the steps of smelting and continuously casting; refining, and carrying out vacuum treatment by using VD for longer than 25min, wherein the content of hydrogen is lower than 2.0PPm; and carrying out blank casting treatment, namely carrying out hot delivery and hot charging, wherein the blank casting temperature is higher than 760 DEG C, a heating zone in a heating furnace is at a weak-oxidative atmosphere, the furnace temperature at the heating zone is 1250-1320 DEG C, the air coefficient at the heating zone is 1.0-1.20, a soaking zone is at a reducing atmosphere, the furnace temperature at the soaking zone is 1150-1250 DEG C, and the air coefficient at the soaking zone is 0.80-1.00. The surface decarburized layer of the steel rail is smaller than 0.3mm, so that the polishing quantity of an upper rail of a high-speed rail can be reduced; and the structure of the surface layer of the steel rail is refined, so that the hardness of the surface layer can be favorably improved, the surface contact fatigue injury of the steel rail can be reduced, and the service life of the steel rail can be prolonged.

Description

Technical field [0001] The invention belongs to the field of rails for railways, and particularly relates to a rail for high-speed railways with a surface decarburization layer depth of less than 0.3 mm. Background technique [0002] In recent years, there have been more and more high-speed passenger dedicated lines in my country, and the passenger volume of railways has been increasing, and the requirements for rails for passenger dedicated lines have also become higher and higher. The decarburization layer is an important factor that affects the performance of the rail. The wheel is in direct contact with the rail head tread. The rail tread is severely decarburized and the surface hardness is reduced. This will cause premature cracks and wavy wear on the surface of the rail, which will significantly reduce the rail's performance. Service life. [0003] At present, the rails used for passenger transportation at home and abroad are mainly high-carbon steel (without other alloying ...

AI Technical Summary

Problems solved by technology

However, the depth of the decarburization layer of the existing rails can only be controlled within 0.5mm, which cannot meet the requirement of less than 0.3mm

[0005] At present, there are two main technologies to reduce the decarburization depth of the rail. One is to spray paint on the surface of the slab to reduce decarburization after the slab is off-line and cooled. The surface is sprayed with paint, and the slab is reheated before the rail is rolled. The reheating of the slab consumes energy, increases production costs, and affects the production rhythm

[0006] Another method is to improve the decarburization depth of the slab by controlling the heating conditions or reduce the decarburization depth of the rail by changing the rolling process. This method requires stable fuel composition, high equipment control precision, and difficult operation. and the effect is not obvious

[0007] The patent "A Heating Method for Preventing Decarburization of High-Carbon Billets or Steel Ingots" (CN 1438334A) introduces a heating method for preventing decarburization of high-carbon steel billets or steel ingots. By controlling the ratio of fuel such as air and gas, the excess air coefficient is adjusted. Further control the atmosphere in the furnace to reduce the decarburization of the slab. This method requires the heating furnace to be equipped with a precise control system to precisely control the amount of air and gas, which is difficult to operate and difficult to implement; According to the introduction of the "method", accurately control the air excess coefficient according to the temperature of the slab, change the slab specification according to the rail specification and control the universal rolling compression ratio accordingly, reduce the decarburization depth of the rail, and change the slab specification to frequently replace the supporting equipment of the continuous casting machine , the operation control is difficult, which affects the production rhythm, and can only control the decarburization layer of U71Mn rail within 0.5mm.

[0008] Patent "A Rolling Method for Controlling Rail Head Decarburization" (CN 102240671A), which reduces the depth of rail decarburization layer by changing the rail head pass system, and requires strict control of pass reduction and special pass system , there is great difficulty in designing and processing rolls, and the reduction of decarburization layer is limited. It can only reduce the decarburization layer of rail to about 0.33mm, and it cannot guarantee that the decarburization layer is completely less than or equal to 0.3mm

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