Table of contents
What is AHSS steel plate?
High intensity meaning of AHSS
Application of AHSS in automotive panels
Application of AHSS on vehicle body frame
Application of AHSS board in automobile chassis
What is AHSS steel plate?
AHSS steel plate refers to a steel plate 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.
High intensity meaning of AHSS
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.
Application of AHSS on automotive 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.
Application of AHSS on vehicle body frame
With the improvement of impact safety standards for frontal impacts and side impacts, 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 strengthened 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 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 in the early days of use, tailor-welded materials were only used on small parts for the purpose of improving material utilization, they have recently been expanded to use in large parts such as body side panels and trunk floors. Tailored welded blanks mainly use 400-590MPa grade high-strength steel plates, and 780MPa-grade and 980MPa-grade high-strength steel plates are also used.
Application of AHSS boards on 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.