High strength automotive steel plate

High-strength steel plates refer to steel plates obtained by strengthening ordinary steel plates. Strengthening principles: solid solution strengthening, precipitation strengthening, fine grain strengthening, structure strengthening (phase change strengthening and composite structure strengthening), aging strengthening and processing strengthening, etc. Among them, the first five types control the sheet properties by adding alloy components and heat treatment processes. The meaning of high strength of high strength steel plate

a. The yield strength and tensile strength are high, within the range of 270-3l0MPa. The tensile strength of high-strength steel plates used for automobile parts can reach 600-800MPa, while the corresponding tensile strength of ordinary cold-rolled mild steel plates is only 300MPa;

b. The application of high-strength steel plates can reduce the weight of stamping parts, save energy and reduce the cost of stamping products.

In Japan, hot-rolled steel strips with a tensile strength of not less than 490MPa and cold-rolled steel strips with a tensile strength of not less than 340MPa are called high-strength steel. High-strength steel plates can reduce the mass of parts, improve the safety of vehicle collisions, and improve the appearance quality and dent resistance of parts. Therefore, they have been increasingly used in car body production in recent years.

1. Application of high-strength steel in automobile panels

Roofs, doors, and other components are required to have deformation stiffness and dent resistance, and bake-hardened steel plates (BH steel plates) with a tensile strength of 340 to 390 MPa are mainly used. The yield strength of BH steel plates increases during baking and painting, which can improve dent resistance and thin steel plates without losing formability. Now, some models have used 440MPa BH type high-strength steel plates.

The body structure of the new Mazda 2 uses 440, 590, 780 and 980Mpa grade high-strength steel plates and ultra-high-strength steel plates.

2. Application of high-strength steel plates in vehicle body frames

With the improvement of impact safety standards for frontal impact and side impact, structural parts, reinforcements, etc. mainly use 590MPa grade high-strength steel plates, and some manufacturers also use 780MPa grade and 980MPa grade high-strength steel plates.

Front anti-collision beam outer panel
Some manufacturers even stamp and form 390MPa and 440MPa grade high-strength steel plates, then conduct high-frequency heating and quenching of the reinforced parts to make the local tensile strength of the parts reach 1200MPa. They also cool the heated steel plates while stamping them to make the parts as a whole Method to achieve tensile strength of 1470MPa.

High-strength steel U-shaped carriage structure popular in Europe
In addition, laser tailor welding is also used to join steel plates of different thicknesses and materials so that the material configuration is suitable for the required materials and usage parts.

Although tailor-welded materials were initially used only for small components in order to improve material utilization, they have recently been used in large-scale components such as body side panels and trunk floors. Tailored welded plates mainly use 400-590MPa grade high-strength steel plates, and 780MPa-grade and 980MPa-grade high-strength steel plates are also used.

3. Application of high-strength steel plates in automobile chassis

The materials used have been developed from traditional 440MPa grade hot-rolled plates to 780MPa, with a maximum weight reduction of 30%. In recent years, the proportion of high-strength steel plates used in chassis has increased dramatically. In the future, the proportion of high-strength steel plates used and the application of higher-strength steel plates are expected to further increase.