Hot stamping bake toughening steel based on carbon partitioning principle and processing method thereof

Abstract

The invention relates to the field of metallurgical materials, also belongs to the field of advanced high-strength steel for cars and particularly provides hot stamping bake toughening steel based on a carbon partitioning principle and a processing method thereof. The hot stamping bake toughening steel comprises the following chemical components in percentage by mass: 0.2-0.5% of C, 0.25-1.5% of Mn, 0.2-0.6% of Cr, 0.2-1.0% of Mo, 0.1-0.8% of Ni, 0.2-1.2% of Si, 0.2-0.5% of Al, 0.002-0.004% of B, 0.02-0.03% of Ti, 0.5-1.5% of Cu, less than 0.01% of S and less than 0.01% of P. The processing method comprises the following steps: heating a steel plate until complete austenitizing, then immediately transferring onto a hot stamping apparatus, stamping, performing intra-mold pressure-maintained quenching, demolding, and cooling in air to room temperature, wherein the structure is martensite+unstable residual austenite; and performing baking treatment in a car body baking temperature range, and ensuring that carbon partitioning is performed to stabilize the residual austenite, thus finally obtaining a multiphase structure of the stable martensite and residual austenite, wherein the comprehensive property is consistent with that of traditional Q&P steel. According to the invention, on the basis of keeping the advantages of the Q&P steel, the disadvantages of the Q&P steel such as need of an independent isothermal partitioning apparatus and requirement for high transfer speed are overcome.

Description

technical field [0001] The invention relates to the field of metallurgical materials, and also belongs to the field of advanced high-strength steel for automobiles, specifically a hot stamping-bake toughening (Hot Stamping-Bake Toughening, HS-BT) steel based on the principle of carbon partitioning and a processing method thereof. Background technique [0002] The use of advanced high-strength steel is one of the important means of automobile lightweight. At present, advanced high-strength steel (such as: boron steel 22MnB5) often adopts hot stamping process. The process principle is to quickly transfer the workpiece to the mold after austenitization, and carry out During the stamping and pressure quenching process, the quenched martensite structure is obtained under the cooling rate of >30°C / s, the tensile strength is 1500MPa, the plasticity is only about 6%, and the strong plasticity product is about 9000MPa·%. In the prior art, there is still a lack of steel for hot sta...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the shortcomings of Q&P steel, the present invention provides a hot stamping, baking and toughening (HS+BT) steel and its processing method based on the principle of carbon partitioning, which solves the need for separate isothermal treatment equipment for the carbon partitioning of Q&P steel, and simultaneously transfers it to Distributing equipment increases the difficulty of process realization and other issues

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