440MPa-tensile-strength hot-rolled high-strength steel sheet and production method thereof

Abstract

The invention discloses a 440MPa-tensile-strength hot-rolled high-strength steel sheet and a production method thereof. The steel comprises the following chemical components in percentage by weight: 0.05-0.08% of C, 0.10-0.30% of Si, 0.60-1.20% of Mn, at most 0.025% of P, at most 0.012% of S, 0.01-0.03% of Nb, 0.01-0.03% of Als, and the balance of Fe and inevitable impurities. The preparation method comprises the following steps: desulfurizing molten iron, smelting in a converter, and carrying out alloying treatment; carrying out ladle furnace treatment while feeding a silico-calcium wire; carrying out continuous casting and continuous rolling; discharging the casting blank, and carrying out high-pressure water dephosphorization; carrying out seven-pass rolling; carrying out laminar cooling; coiling; carrying out acid washing; flattening; and finishing. The steel has the advantages of stable performance, high dimensional accuracy and favorable elongation percentage, can be used for passenger vehicles chassis, various reinforcing plates and other automobile structural members and safety members, and lowers the automobile production cost; and the production method has the advantages of low production cost and favorable adaptability to industrial production.

Description

technical field [0001] The invention belongs to the technical field of steel for automobiles, and specifically refers to a hot-rolled high-strength thin steel plate with a tensile strength of 440 MPa and a production method. Background technique [0002] With the development of automobile lightweight technology, the thinning of high-strength steel for automobile structure and safety is the most direct way for automobile lightweight. At present, the thin-gauge steel plates commonly used in automobile production are mainly used in the production of parts such as automobile chassis systems, body structure systems, and seat safety systems. [0003] Compared with the traditional hot-rolling production line, the hot-rolled steel plate produced by the thin slab continuous casting and rolling (CSP) method has the characteristics of short process, high strength, low cost, especially thin thickness specification, and is an effective means for automobile lightweight . Taking advantag...

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Problems solved by technology

However, the high-strength steel produced by the above-mentioned advanced steel mills at home and abroad by the CSP method has achieved certain technical effects, but in order to pursue the comprehensive performance of steel products, they have added more alloying elements to the steel, resulting in an increase in the cost of the steel , and the thickness of the steel they produce is higher than 2mm, and the thickness of the product needs to be further improved

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