Ultralow-carbon bake-hardened steel plate blank and control method of solid solution carbon content thereof

Abstract

The invention relates to an ultralow-carbon bake-hardened steel plate blank which comprises the following chemical components in percentage by weight: 0.0015-0.0030% of C, at most 0.03% of Si, 0.30-0.60% of Mn, 0.030-0.050% of P, at most 0.015% of S, 0.015-0.060% of Alt, 0.005-0.025% of Nb, at most 0.0050% of N, 0.0005-0.0020% of B and the balance of Fe. The invention also relates to of a control method of the solid solution carbon content of the ultralow-carbon bake-hardened steel, which comprises the following steps: sequentially carrying out pre-desulfurization and slag removal treatment on molten iron to obtain first molten iron with the sulfur content of at most 0.003%; smelting the first molten iron to obtain first molten steel with the carbon content of 0.025-0.050%; refining the first molten steel by a vacuum refining furnace to obtain second molten steel; sending the second molten steel into a continuous casting procedure, injecting into a carbon-free tundish, and casting the molten steel to obtain the ultralow-carbon bake-hardened steel plate blank, wherein the carbon increase amount of the second molten steel in the continuous casting process is at most 0.0003%. The control method shortens the smelting time in the vacuum refining furnace, enhances the production efficiency, and enhances the primary smelting hit rate of the plate blank composition.

Description

technical field [0001] The invention relates to the technical field of steelmaking, in particular to an ultra-low carbon bake hardened steel slab and a method for controlling the solid solution carbon content thereof. Background technique [0002] Bake hardening value is an important performance index of bake hardening steel. The solid solution carbon content has a great influence on the bake hardening value, especially for ultra-low carbon bake hardenable steels. Therefore, in the development process of ultra-low carbon bake-hardening steel, the requirements for solid solution carbon content are generally very strict, and the error range of the target value is as narrow as ±0.0003% by mass. The solid solution carbon content is mainly controlled by the carbon content and the content of alloying elements such as Nb, and is generally controlled by adjusting the amount of Nb alloy added according to the carbon content. [0003] The production method of ultra-low carbon bake-h...

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Problems solved by technology

[0004] The embodiment of the present application provides an ultra-low-carbon bake-hardening steel slab and a method for controlling its solid solution carbon content, which solves or partially solves the problem that the production method of ultra-low-carbon bake-hardening steel in the prior art cannot control carbon well. The deviation of element content causes the technical problem of low smelting hit rate of solid solution carbon content, long smelting time and high cost, which realizes shortening smelting time in vacuum refining furnace, improves production efficiency and improves slab composition at one smelting hit The technical effect of rate

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