A thermoformed member with a tensile strength of 1800mpa or more and excellent cold bending performance and its preparation method

Abstract

The invention discloses a hot-forming component with the tensile strength being above 1800MPa grade and an excellent cold bending performance, and a preparation method thereof. The hot-forming component is prepared from the following chemical components in percentage by weight: 0.29 to 0.35 percent of C, less than or equal to 0.5 percent of Si, 0.5 to 1.5 percent of Mn, less than or equal to 0.020percent of P, less than or equal to 0.010 percent of S, less than or equal to 0.50 percent of Cr, 0.01 to 0.06 percent of Al, 0.01 to 0.06 percent of Nb, 0.01 to 0.06 percent of V, less than or equalto 0.5 percent of Mo, and the balance Fe and inevitable impurities. A surface layer of the hot-forming component is a soft-phase ferritic structure, an inner layer of the hot-forming component is a martensitic structure, and the grain size is less than or equal to 10 mum. By adopting the component designs with low Si, low Mn, low Cr, zero Ti, zero B, and Mo, and combining thermal mechanical control processing (TMCP), continuous annealing and hot forming processes, the high-toughness hot-forming steel with the tensile strength being larger than or equal to1800MPa grade and well-closed formation is obtained; and in the preparation process, through the control of a preparation technology, a decarburized layer with the thickness ranging from 15 to 25 mum is obtained after hot rolling, so thatthe cold bending performance of the hot-forming component is improved.

Description

technical field [0001] The invention belongs to the technical field of thermoformed steel, and in particular relates to a thermoformed component with a tensile strength above 1800 MPa and excellent cold bending performance and a preparation method thereof. Background technique [0002] Automobile lightweight technology is one of the key technologies to adapt to the trend of modern automobile safety, energy saving and environmental protection. At present, more and more automobile body parts use thermoforming technology (such as: automobile bumpers, anti-collision beams, A-pillars, B-pillars , door bumper, etc.). Thermoforming technology is a new process that divides forming and strengthening into two steps to produce ultra-high-strength auto parts. The produced parts have the advantages of ultra-high strength, high forming precision, and no springback. [0003] At present, the hot-formed steel widely used in the market is 1500MPa strength level. As the laws and regulations o...

AI Technical Summary

Problems solved by technology

However, when the strength increases, the corresponding plastic toughness will decrease. The important index for evaluating the plastic toughness of thermoformed steel is the three-point bending performance (refer to VDA238-100 for test standards)

Insufficient cold bending performance (bending limit angle) of materials or parts used in automobiles will lead to premature brittle fracture of parts during vehicle collision, which cannot effectively absorb the energy generated by the collision, and is not conducive to the safety of occupants

Images