B-containing martensitic steel strip and manufacturing method thereof

Abstract

The invention relates to a B-containing martensitic steel strip and a manufacturing method thereof. The B-containing martensitic steel strip comprises the following components in percentage by weight:0.16-0.26% of C, 0.1-0.5% of Si, 0.4-1.7% of Mn, smaller than or equal to 0.02% of P, smaller than or equal to 0.007% of S, 0.004-0.010% of N, smaller than 0.001% of Als, 0.001-0.006% of B, 0.007-0.020% of total oxygen [O]T, the balance of Fe and inevitable impurities, one or two of 0.1-0.6% of Cu or 0.005-0.04% of Sn, one or two of 0.01-0.08% of Nb and 0.1-0.4% of Mo, and greater than 250 of Mn / S. According to the B-containing martensitic steel strip, residual Sn, Cu and other elements in scrap steel are used for smelting, and Nb / Mo and other microalloy elements and an element B are selectively added. According to the B-containing martensitic steel strip, the yield strength is 800-1200 MPa, the tensile strength is 1100-1900 MPa, the elongation is 3-12%, the martensitic steel strip can bewidely applied to the field of high-strength automotive steel, and a wide space is provided for the automobile industry in the aspects of light weight, energy consumption reduction and fuel economy improvement.

Description

technical field [0001] The invention belongs to the technical field of continuous casting technology, and in particular relates to a B-containing martensitic steel strip and a manufacturing method thereof. Background technique [0002] In the traditional steel production process, tin (Sn) and copper (Cu) are typical residual or harmful elements in steel. It is very difficult and expensive to fully remove Sn and Cu in the steelmaking process. Once the steel contains Sn , Cu, basically cannot be completely eliminated, and the content of Sn and Cu can only be reduced by diluting molten steel, which all lead to an increase in the cost of smelting steel products. [0003] In recent years, due to the continuous recycling of steel scrap, there are more and more scrap steel resources, and the electricity price has also continued to decrease. Domestic short-process electric furnace steelmaking based on scrap steel is increasingly rising, resulting in the gradual increase in the conte...

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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

[0014] 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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