Method for improving thickness of decarburized layer of small square billet of tire cord steel

Abstract

The invention belongs to the technical field of the metallurgy and processing of iron and steel and provides a method for improving the thickness of a decarburized layer of a small square billet of tire cord steel. The tire cord steel is produced by adopting the technological processes of heating, rough rolling, intermediate rolling, pre-finishing, finishing and air cooling. The method for improving the thickness of the decarburized layer of the small square billet of the tire cord steel comprises the following steps that: prior to the technological process of heating, corner grinding or whole-stripping treatment is carried out on the square billet; the total detention time for the square billet in a heating furnace is less than 150 min, and the detention time in a soaking section is lessthan 45 min; fuel gas is fully combusted in the soaking section, wherein the air-fuel ratio in a heating I section is set to be 1.1, the air-fuel ratio in a heating II section is set to be 0.9, and the air-fuel ratio in the soaking section is set to be 0.7; the temperature of the heating I section is 600-700 DEG C, the temperature of the heating II section is 950-1,050 DEG C, the temperature of the soaking section is 1,150-1,180 DEG C; the temperature for starting rolling is controlled at 1,100-1,150 DEG C; and the temperature difference between coil rod overlapping points and a center duringthe whole process of rolling is no more than 50 DEG C. With the adoption of the method, the thickness of the decarburized layer of the small square billet of the tire cord steel is greatly improved, and the thickness of a total decarburized layer (ferrite and transition layer) of a hot-rolled coil rod of a tire cord steel finished product can be less than 0.06 mm, so that the requirements of tirecord steel users on the control of the thickness of the decarburized layer are met.

Description

technical field [0001] The invention belongs to the technical field of iron and steel metallurgy and processing, and relates to a method for controlling the thickness of the decarburized layer of a billet, in particular to a method for improving the thickness of the decarburized layer of a cord steel billet. Background technique [0002] Cord steel is an ideal skeleton material for rubber products, especially car radial tires. Cord steel is a fine product of high-quality hard wire steel, a representative product of ultra-clean steel, a symbolic product of the production level of wire rods in iron and steel enterprises, and the steel with the highest strength among commercial steels. It has special requirements for every link of smelting, rolling, processing, etc. in production, and it is an out-and-out high-quality steel in the whole process. Since the carbide in the steel is both a strengthening phase and a wear-resistant phase, the decarburization of the steel wire surfac...

AI Technical Summary

Problems solved by technology

If the decarburization on the surface of the steel wire exceeds the standard, the hardness will decrease, thereby reducing the resistance to the expansion of the tissue crack source and reducing the fatigue life

The surface decarburization depth of the cord steel wire rod is greater than 0.10mm, and it is very easy to break the wire during the drawing and plying process

At present, there are no in-depth reports on the decarburization of cord steel corners in China.

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