Manufacturing method of automotive U-shaped beam

Abstract

The invention provides a manufacturing method of an automotive U-shaped beam. The method comprises the steps that a steel plate is heated to a temperature between Ac1 transformation temperature and Ac3 transformation temperature and then stays for 1-2 min under the temperature; the steel plate is cooled to a temperature higher than the martensite transformation starting temperature Ms point at a cooling speed of 9-11 DEG C / s; the steel plate is placed into a U-shaped beam die and is formed for 1.9-2.1 s after spotting, and the forming termination temperature is controlled to be higher than the martensite transformation starting temperature Ms point; the circulating cooling speed inside the die is set to be 25 DEG C / s, and stamp-forming of the U-shaped beam is achieved after spotting pressure maintaining is kept for 10 s. According to the manufacturing method of the automotive U-shaped beam, cracks or wrinkles will not appear in the forming process, the Rm value reaches more than 948 MPa, the Rp0.2 value reaches 518 MPa, the A value reaches 12.33%, and therefore the automobile U-shaped beam with high strength, good forming property and good malleability is obtained.

Description

technical field [0001] The invention belongs to the technical field of compression molding, and in particular relates to a production method of an automobile U-shaped beam with good ductility. Background technique [0002] In the field of automobile body structure, light weight has been paid more and more attention by the industry. Reducing the weight of the body can not only effectively improve the safety performance of the vehicle collision, but also reduce the fuel consumption per 100 kilometers by 0.5L and carbon dioxide emissions. Reduced by 12g / km. In order to achieve weight reduction, the strength of the parts must be increased in order to ensure the safety performance of the collision as the material thickness of the parts is reduced. [0003] Automobile U-beams are usually obtained by stamping steel plates. However, in the cold forming process of high-strength steel plates, when the material strength exceeds 800-1000 MPa, the material forming becomes very difficult...

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Problems solved by technology

[0005] However, in the hot forming process, due to the need to heat the blank to a transformation temperature above Ac3, the microstructure of the formed product becomes mostly martensitic, although steel plates with a strength of 1270 MPa or higher can be obtained, However, U-shaped beams have poor ductility and may even crack, so that hot-formed parts have not been widely used. The main reason is that U-shaped beams with high strength and good formability cannot be obtained at the same time.

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