Method for producing martensitic steel strip by twin-roll thin strip continuous casting

Abstract

A method for producing martensitic steel strip by twin-roll thin strip continuous casting, using scrap steel as raw material, making full use of residual Sn, Cu and other elements in scrap steel to smelt molten steel, and selectively adding Nb / Mo etc. Microalloying elements; during the smelting process, by controlling the basicity of slag, the type and melting point of inclusions in steel, the content of free oxygen in molten steel, and the content of acid-soluble aluminum Als; Strip steel, after the strip steel comes out of the crystallization roll, directly enters a lower airtight chamber with a non-oxidizing atmosphere, and enters the on-line rolling mill for hot rolling under airtight conditions; after rolling, the strip steel is quickly cooled by gas atomization Cool to below 300°C, and finally coil to obtain steel coils; it can also be subjected to isothermal tempering treatment, or entered into the continuous annealing production line for aging treatment.

Description

technical field [0001] The invention belongs to the continuous casting process, and in particular relates to a method for producing martensitic steel strip by twin-roll thin strip continuous casting. 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 (inclusive), it is relatively ...

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

[0011] However, due to the rapid solidification process characteristics of thin strip continuous casting, the produced steel generally has the problems of uneven structure, low elongation, high yield ratio, and poor formability; The grains have obvious inhomogeneity, which will lead to the inhomogeneous structure of the final product obtained after austenite transformation, resulting in unstable performance of the product

Therefore, it is difficult and challenging to use a thin strip continuous casting production line to produce some high-strength products required by the automotive industry and the petrochemical industry. Therefore, when using thin strip continuous casting to produce high-strength martensitic steel, the traditional composition should be copied Craftsmanship cannot be produced and requires a breakthrough in composition and craftsmanship

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