High-strength, thin-gauge and high-corrosion-resistance steel and manufacturing method thereof

Abstract

The invention discloses high-strength, thin-gauge and high-corrosion-resistance steel and a manufacturing method thereof. The high-strength, thin-gauge and high-corrosion-resistance steel comprises, by weight, 0.02-0.06% of C, 0.1-0.5% of Si, 0.4-1.7% of Mn, less than or equal to 0.02% of P, 4.0-6.0% of Cr, 1.0-3.0% of Ni, less than or equal to 0.007% of S, 0.004-0.010% of N, less than 0.001% of Als, 0.001-0.006% of B, 0.007-0.020% of total oxygen [O]T and the balance Fe and inevitable impurities, meanwhile, the high-strength, thin-gauge and high-corrosion-resistance steel contains one or twoof 0.01-0.08% of Nb and 0.01-0.08% of V, and the Mn / S ratio is greater than 250. According to the manufacturing method, the microalloy elements such as Nb / V and the B element are selectively added into steel, and the alkalinity of slag, the type and melting point of inclusions in the steel, the content of free oxygen in molten steel and the content of acid-soluble aluminum Als are controlled in the smelting process; then, double-roller thin-strip continuous casting is adopted for casting a cast strip, and the cast strip enters an online rolling mill under the closed condition to be subjected to hot rolling; and after rolling, a gas atomization cooling mode is adopted for cooling the strip steel.

Description

technical field [0001] The invention relates to corrosion-resistant steel and a manufacturing process thereof, in particular to a high-strength thin-spec high-corrosion-resistant steel and a manufacturing method thereof. Background technique [0002] Most of the traditional thin strip steel is produced by multi-pass continuous rolling of the slab with a thickness of 70-200mm. The traditional hot rolling process is: continuous casting + slab reheating and heat preservation + rough rolling + finishing rolling + cooling + Coiling, that is, firstly obtain a cast slab with a thickness of about 200mm through continuous casting, reheat the cast slab and keep it warm, then perform rough rolling and finish rolling to obtain a steel strip with a thickness generally greater than 2mm, and finally process the steel strip Laminar cooling and coiling complete the whole hot rolling production process. If it is necessary to produce a steel strip with a thickness of less than 1.5mm (inclusiv...

AI Technical Summary

Problems solved by technology

At the same time, the contact of high-temperature strip steel with cooling water will cause many problems: first, water spots (rust spots) will be formed on the surface of the strip steel, which will affect the surface quality; second, the cooling water used for laminar flow cooling or spray cooling It is easy to cause uneven local cooling on the surface of the strip, resulting in uneven microstructure inside the strip, resulting in uneven properties of the strip and affecting product quality; third, uneven local cooling on the surface of the strip will cause deterioration of the shape of the strip , affecting the shape quality

[0017] (1) Long process flow, high energy consumption, many units and equipment, and high infrastructure costs lead to high production costs

[0018] (2) Corrosion-resistant steel contains a relatively high content of copper and other segregation-prone elements that improve the corrosion resistance of the steel strip. The traditional process is prone to macro-segregation of copper and other elements due to the slow solidification and cooling of the slab, resulting in various segregation of the slab. Anisotropy and macro cracks appear, and the yield is low

As a result, the corrosion resistance of the steel strip is not high

[0020] (4) The corrosion resistance of these corrosion-resistant steels cannot achieve the corrosion resistance requirements of the steel of the present invention, and the present invention requires that the traditional corrosion-resistant steel be doubled

[0021] (5) In the traditional process, since the microalloying elements cannot be maintained as a solid solution during the hot rolling process, partial precipitation occurs, resulting in fine grains of the steel structure, increased yield ratio, and poor formability, which will significantly increase the rolling load. Increase energy consumption and roll consumption, and cause greater damage to equipment, thus limiting the economical and practical production of high-strength corrosion-resistant steel hot-rolled products. Thickness range, usually ≤ 2mm

This not only increases the investment cost, but also significantly increases the floor area of ​​the thin strip continuous casting and rolling production line, reducing the advantages of the production line

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