Cold-rolled high-strength steel with good coating quality and preparation method thereof

Abstract

The invention discloses cold-rolled high-strength steel with good coating quality and a preparation method thereof. The steel comprises the following chemical components in percentage by mass: 0.08-0.30% of C, less than or equal to 2% of Si, less than or equal to 3% of Mn, less than or equal to 1% of Al, less than or equal to 0.01% of B, 0-1.5% of Cr, less than or equal to 0.010% of P, less than or equal to 0.006% of S and the balance Fe and other inevitable impurities. Granular oxide with the maximum size smaller than or equal to 1 micrometer is dispersed and distributed on the surface of the steel, and the ratio w of the area of the granular oxide to the surface area of the steel is larger than 1% and smaller than 20%. The method comprises the steps that the chemical components of the steel are subjected to continuouse casting and heating after being smelted, and then subjected to roughly rolling, finely rolling, cooling and coiling to obtain a hot-rolled finished product; the hot-rolled finished product is subjected to acid pickling and cold rolling to obtain chilled strip steel; and the chilled strip steel is annealed and then subjected to surface film plating treatment. The obtained cold-rolled high-strength steel has the good coating characteristic, and a phosphating film is good in growing status.

Description

Technical field [0001] The present invention relates to the preparation of cold rolling high strength steel, and in particular, to a cold rolling high strength steel having good coating quality and a preparation method thereof. Background technique [0002] Cold rolling high steel is an important support material for automobile weight loss. With the speed of light weight of the car body, more and more cold rolled high steel is used for body manufacturing, such as double phase steel, TRIP steel, psycho steel, martensg steel, etc. These cold-rolled high steel tissues are mostly a combination of martensite and ferrite and a small amount of austenite. The common characteristics of these cold rolled high steel are enhanced through phase transitions, and in order to achieve different phase change processes, there is a need to add a variety of alloy elements, such as manganese, silicon, chromium, aluminum, boron, etc., for controlling the annealing process. The transition speed and tend...

AI Technical Summary

Problems solved by technology

This kind of oxide film is extremely unfavorable to the coating process of high-strength steel in automobile production, and it is easy to cause difficulty in surface phosphating during coating, and it is impossible to form a complete phosphating film, resulting in poor quality of electrophoretic film

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