A kind of preparation method of medium carbon alloy steel

Abstract

The invention discloses a preparation method of medium carbon alloy steel (Q345A-D / Q345X) and relates to the field of metallurgy continuous casting. The preparation method comprises the steps that a secondary cooling water distribution model is optimized, the content of ALx and the content of N are controlled accurately, the content of the ALs is controlled to be no more than 300ppm, the content of the N is controlled below 400ppm, the conical degree of a narrow surface of a crystallizer is adjusted, the conical degree value is adjusted from 1.0% to 1.1%, the accuracy of a device is improved, the device inspection is improved, and the condition of the device is guaranteed to be good. According to the medium carbon alloy steel, transverse corner crack of the medium carbon alloy steel is controlled effectively, the occurrence rate of the transverse corner crack is reduced to 0.92% from the initial 12.5%, the chamfering amount of the casting blank is reduced greatly, and the surface quality of the casting blank is improved at the same time.

Description

technical field [0001] The invention relates to the field of metallurgical continuous casting, in particular to a preparation method of medium-carbon alloy steel. Background technique [0002] With the development of the economy, the market demand for high-strength steel continues to increase. By adding Nb, V, Ti and other microalloying elements into the steel and cooperating with the controlled rolling and controlled cooling technology in the hot rolling process, the second phase particles formed in the steel play the role of grain refinement and dispersion strengthening, which significantly improves the strength of steel. Although the addition of microalloying elements in steel helps to improve the strength of steel, in the continuous casting process, microalloying elements such as Nb, V, Ti in steel form fine dispersed carbides, nitrides and carbonitrides with C and N. , and precipitate in the austenite grain boundary or film-like ferrite at the grain boundary, which ma...

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Problems solved by technology

[0003] When Shougang Qian'an Iron and Steel Company produces medium-carbon alloy steels (Q345A-D / Q345X), the incidence of corner and transverse cracks is 12.5%, which seriously affects the quality of continuous casting slabs and continuous casting production, increasing production Cost; at the same time, the transverse cracks at the corners of the slab are inherited to the hot-rolled coils, which are prone to edge tongue-shaped cracks, resulting in a reduction in the success rate of the coils. The slabs with corner cracks need to be corner-cut. The longer time will affect the production organization, prolong the delivery cycle, and have a direct impact on the contract fulfillment rate

However, due to the complex formation mechanism of corner transverse cracks and many influencing factors, this problem has not been well solved so far.

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