Hot forming process of automobile high strength steel

The so-called hot forming, fully known as hot stamping forming, is a new technology specially used for automotive high-strength steel sheet stamping parts in recent years, and it is also one of the key technologies to realize automotive lightweight production. Hot stamping starts from high strength steel plate. Hot forming technology is the use of heat treatment and high-temperature forming to improve the strength of the final parts, which is mainly divided into direct forming and indirect forming. It has the outstanding advantages of high forming precision and good formability, and is suitable for parts with high safety requirements, such as anti-collision beam, a, B, C pillar reinforcing plate, etc.

Although the replacement of low-strength steels such as low-carbon steel by high-strength steels helps to reduce the weight of automobiles, it also brings new difficulties to automobile manufacturing. With the improvement of yield strength and tensile strength, the stamping forming performance of high-strength steel is declining, and various forming defects are prominent. It not only needs a very large forming force, but also has a very serious springback, so it is difficult to ensure the dimensional accuracy of the parts. In this case, in order to obtain the ultra-high strength of parts and improve the formability of high strength steel, hot stamping technology came into being. That is to say, the higher the strength of steel plate is, the more difficult the forming is. When the strength exceeds 1000MPa, some parts with complex geometry can hardly be formed by common cold stamping process. The strength of stamping parts made by hot stamping technology can be as high as 1500MPa, and there is almost no rebound in high temperature forming, which has the outstanding advantages of high forming precision and good formability. This makes hot stamping technology gradually become a hot technology in the field of automobile manufacturing, which is widely used in door anti-collision beam, front and rear bumper and other safety parts, as well as A-pillar, B-pillar, C-pillar Production of column, middle passage and other car body structural parts.

In summary, the advantages of hot forming technology are: to obtain ultra-high strength body parts, reduce the weight of the body, improve the safety and comfort of the body, improve the stamping formability, control the rebound, improve the dimensional accuracy of the parts, reduce the yield strength of the material at high temperature, reduce the requirements for the tonnage of the press, and improve the weldability, surface hardness, concave resistance and corrosion resistance Erodibility and so on. The disadvantages are: large investment in equipment, complex mold design and processing, high manufacturing and maintenance costs, relatively high cost of single part, new challenges of part connection technology and so on.

Hot forming technology is based on the traditional stamping process, combined with the characteristics of hot forging technology, the material is heated and then the product is manufactured. The stamping heat treatment can be completed at one time because the sheet is heated to the complete austenitizing temperature first and then quenched in the grinding tool.

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