High-hole-expansion steel based on scrap steel raw material and production method thereof

Abstract

The invention discloses high-hole-expansion steel based on a scrap steel raw material and a production method thereof. The high-hole-expansion steel comprises, by weight, 0.01-0.05% of C, 0.2-0.6% ofSi, 0.8-1.5% of Mn, less than or equal to 0.02% of P, less than or equal to 0.005% of S, less than or equal to 0.008% of N, less than 0.001% of Als, less than or equal to 0.0050% of Ca, 0.007-0.02% oftotal oxygen [O]T and the balance Fe and inevitable impurities, and also contains one or two of 0.1-0.6% of Cu and 0.005-0.04% of Sn, wherein the Mn / S ratio is greater than 250. According to the method, the scrap steel is adopted as a raw material, and residual elements such as Sn and Cu in the scrap steel are fully utilized for smelting; the alkalinity of slag, the type and melting point of inclusions in the steel, the content of free oxygen in molten steel and the content of acid-soluble aluminum Als are controlled; and then, double-roller thin-strip continuous casting is carried out to cast a cast strip, the cast strip directly enters a lower closed chamber with a non-oxidizing atmosphere after being discharged out of crystallization rollers and enters an online rolling mill under theclosed condition to be subjected to hot rolling, and strip steel obtained after rolling is cooled in a gas atomization cooling mode.

Description

technical field [0001] The invention relates to the manufacturing technology of high-hole-expanding steel, in particular to a high-hole-expanding steel based on scrap steel raw materials and a production 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 increas...

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Problems solved by technology

[0011] With the increasing requirements of automobile design on the chassis structure, the forming of parts is more complex, and the requirements for flanging and hole reaming performance of steel plates are further improved. The strength and rigidity of parts can be improved through the shape design of flanging and local reaming of automobile parts, which can To achieve the purpose of reducing the thickness and weight of automobile steel plates, traditional carbon-manganese solid-solution strengthened steel and low-alloy precipitation-strengthened steel structural steel plates are difficult to meet the forming requirements of automobile chassis and cantilever parts, such as traditional 440MPa steel plate carbon-manganese solid-solution strengthened steel and low-alloy The hole expansion rate of precipitation strengthened steel is only between 50% and 70%, thus the high hole expansion steel was born

In the 1990s, the United States and Japan successively developed hot-rolled steel sheets with high hole expansion performance of 440-780MPa, and the hole expansion rate was 70%-131%. They are mainly used in formability, especially those that require good flanging performance. For automobile chassis, wheels and other parts, the hole expansion performance of the steel plate is related to the composition, strength and structure uniformity of the steel plate. Because it contains more precious alloy elements Cr, Nb, Ti, V and Mo, etc. Ferrite / bainite dual phase structure can be obtained under the same conditions, but its cost is higher

[0023] Chinese patents CN105154769 and CN106119702 respectively disclose a kind of 780MPa and 980MPa grade hot-rolled high-strength high-reaming steel and its manufacturing method, both of which are in the category of high-strength steel. Multi-microalloying elements are used to strengthen the steel type, and the alloy cost is relatively high; at the same time, its production method adopts traditional continuous casting + traditional hot rolling process to produce

[0024] International patent WO200928515 uses C, Si, Mn to add a small amount of Nb, Ti alloy elements, and can produce reaming steel with a tensile strength above 490MPa. Hot rolling must adopt a two-stage laminar flow cooling method, which can be more accurately simulated in the laboratory. However, in hot rolling production, the strip speed changes greatly during hot rolling, and the temperature of the steel plate in the air cooling section cannot be measured. A two-stage cooling model is used to control laminar cooling, and the steel plate The actual temperature fluctuates greatly, which will easily lead to large fluctuations in the performance of the steel coil head, middle and tail

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