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

Abstract

The invention discloses a method for producing a martensitic steel strip through twin-roll thin-strip continuous casting. According to the method, scrap steel is adopted as a raw material, smelting ofmolten steel is carried out by fully utilizing residual elements such as Sn and Cu in the scrap steel, and microalloy elements such as Nb / Mo are selectively added into the steel; in the smelting process, the alkalinity of slag, the types and melting points of inclusions in the steel, the content of free oxygen in the molten steel and the content of acid-soluble aluminum Als are controlled; then strip steel with a thickness of 1.5-3 mm is cast through twin-roll thin-strip continuous casting, and the strip steel directly enters a lower closed chamber with a non-oxidizing atmosphere after beingdischarged out of a crystallization roller and enters an online rolling mill under the closed condition to be subjected to hot rolling; the strip steel is cooled to 300 DEG C or below in a rapid gas atomization cooling manner after being rolled; and finally coiling is carried out to obtain a steel coil; and isothermal tempering treatment can also be carried out, or aging treatment can be carried out in a continuous annealing production line.

Description

technical field [0001] The invention belongs to the continuous casting process, in particular to a method for producing martensitic steel strips by twin-roll 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 the steel strip Laminar cooling and coiling complete the whole hot rolling production process. If it is to produce a steel strip with a thickness less than 1.5mm (inclusive), it is relatively difficult, and it is usually complete...

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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