Five hundred and ninety Mpa-grade dual-phase steel and production method thereof

Abstract

The invention discloses 590Mpa-grade dual-phase steel and a production method thereof. The 590Mpa-grade dual-phase steel comprises the following components in percentage by mass: less than or equal to 0.20% of C, less than or equal to 1.80% of Si, less than or equal to 2.00% of Mn, less than or equal to 0.050% of P, less than or equal to 0.015% of S, less than or equal to 0.10% of Nb, and less than or equal to 0.10% of Ti; and the production method comprises the steps of pretreatment of hot metal, smelting in a converter, fine adjustment of alloy, smelting in a refined-smelting ladle furnace, continuous casting and hot continuous rolling, wherein according to the hot continuous rolling, heating temperature is 1150-1250 DEG C, finish rolling temperature is 800-900 DEG C, the rolled steel is rapidly cooled to 650-750 DEG C, and air cooling is carried out for 6-11 seconds, the steel is rapidly cooled to a target coiling temperature, and the coiling temperature is 400-500 DEG C. According to the production method, the accuracy control and proportioning of ferrite and bainite are realized through appropriate components and process control, the strength difference of soft and hard of the material can be reduced, a soft and hard two-phase interface is eliminated, and the product has excellent strength-ductility and toughness matching property and good stretching and flanging property.

Description

technical field [0001] The invention relates to the technical field of iron and steel manufacturing, in particular to a 590MPa dual-phase steel and a production method thereof. Background technique [0002] Duplex steel is divided into hot-rolled, cold-rolled and galvanized dual-phase steel according to the production process. Since hot-rolled dual-phase steel eliminates the additional heat treatment process, its weldability and fatigue are better than heat-treated dual-phase steel, so the cost is lower. Low, larger scale of production. In the hot-rolled dual-phase steel, there are mainly ferritic-martensitic dual-phase steel and ferritic-bainite dual-phase steel according to the structure type. At present, ferritic-martensitic dual-phase steel has been widely used in the automobile manufacturing industry, while research on ferritic-bainite dual-phase steel is less, and they are all designed for different application parts. [0003] Since different auto parts often adopt d...

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Problems solved by technology

[0005] At present, the production methods of ferritic and bainitic dual-phase steels at home and abroad basically adopt the addition of precious metal elements such as chromium and molybdenum to control the transformation of supercooled austenite, and at the same time combine constant-speed rolling and segmental cooling to control The amount of transformation of ferrite and bainite after rolling, and the addition of precious metals will obviously cause a significant increase in cost

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