The specification range of cold-rolled high-strength automobile sheets is usually 0.5~1.2mm×800~1850mm, and the strength level is 340~1470MPa. The main varieties include bake-hardened BH steel, dual-phase DP steel and phase transformation-induced plasticity TRIP steel.
Bake-hardened BH steel is used for various covering components such as automobile door outer panels, engine hood panels, trunk outer panels and ceilings. It is an automobile panel with ideal comprehensive properties. Domestic bake-hardened BH steel plates can be divided into categories according to yield strength. For: 180 MPa, 210 MPa, 240 MPa, 270 MPa and 300 MPa and other strength levels.
Bake-hardened BH steel can be divided into three categories: cold-rolled plain plate, electro-galvanized steel and hot-dip galvanized steel according to different production processes.
At present, the outer panels of the new generation of domestic cars mostly use electro-galvanized bake-hardened steel sheets, and the yield strength levels are mainly 180 MPa and 220 MPa.
Dual-phase DP steel is generally used for automotive parts with high strength, high anti-collision absorption capacity and strict forming requirements, such as wheels, bumpers, suspension systems and their reinforcements. With the advancement of steel performance and forming technology, Dual-phase DP steel is also used in interior and exterior panels of automobiles.
TRIP high-strength steel has good formability and strong ability to absorb collision impact energy due to the phase transformation plasticity induced by the transformation of residual austenite in its structure to martensite under the action of stress and strain. It is mainly used in requirements High strength automotive parts that must be drawn and formed, such as door frames, side pillars, etc. exist
In the practical application of cold-rolled high-strength steel plates, China is developing the fastest. Among them, automobile outer panels σb ≥ 400 MPa, car doors and roofs σb = 340~370 MPa, automobile inner panels σb = 400~600 MPa, and automobile components σb = 350~510 MPa, car door frame σb≥800 MPa.
