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

A processing method and hot stamping technology, which is applied in the field of metallurgical materials and advanced high-strength steel for automobiles, can solve problems such as increased difficulty in process realization, and achieve the effects of improving development and technological progress, loose time, and excellent comprehensive performance

Active Publication Date: 2014-12-10
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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

Method used

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

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Experimental program
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Embodiment 1

[0047] In this embodiment, the chemical composition (mass fraction) of the HS-BT steel sample is: 0.4% C, 0.32% Mn, 0.35% Cr, 0.5% Mo, 0.1% Ni, 0.8% Si, 0.2% Al, 0.003% B, 0.025% Ti, 0.5% Cu, 0.005% S, 0.008% P, the balance of Fe. The sheet was heated to 950°C for austenitization for 30 minutes, and then transferred to a press for hot stamping within 10 seconds. The pressure holding and quenching time in the mold was 60 seconds. After pressure holding and quenching, the mold was released and cooled to room temperature. Then the workpiece taken out is placed in a heat treatment furnace at a temperature of 150° C. and a holding time of 60 minutes. The average cooling rate of the hot stamping and pressure quenching process is 36°C / s. Measured by phase change dilatometer, the M of this steel s point at 237°C, M f The point is 80°C.

[0048] The test results of mechanical properties show that the tensile strength of the HS-BT steel is 2205MPa, the elongation is 9.3%, and the st...

Embodiment 2

[0051] In this embodiment, the chemical composition (mass fraction) of the HS-BT steel sample is: 0.35%C, 1.2%Mn, 0.56%Cr, 0.4%Mo, 0.7%Ni, 0.7%Si, 0.4%Al, 0.0028% B, 0.021% Ti, 1.5% Cu, 0.006% S, 0.003% P, the balance of Fe. The sheet is heated to 950°C for austenitization for 30 minutes, and then transferred to a press for hot stamping within 10 seconds. The holding and quenching time is 60 seconds. After holding and quenching, the mold is released and cooled to room temperature. Then the workpiece taken out is placed in a heat treatment furnace at a temperature of 200° C. and a holding time of 30 minutes. The average cooling rate of the hot stamping and pressure quenching process is 36°C / s. Measured by phase change dilatometer, the M of this steel s point at 230°C, M f The point is 50°C.

[0052] The test results of mechanical properties show that the tensile strength of the HS-BT steel is 2158MPa, the elongation is 10.4%, and the strength-plastic product is 22443MPa·% a...

Embodiment 3

[0055] In this embodiment, the chemical composition (mass fraction) of the HS-BT steel sample is: 0.3%C, 0.6%Mn, 0.5%Cr, 1.0%Mo, 0.39%Ni, 1.0%Si, 0.4%Al, 0.0036% B, 0.03% Ti, 1.0% Cu, 0.004% S, 0.005% P, the balance of Fe. The sheet is heated to 950°C for austenitization for 30 minutes, and then transferred to a press for hot stamping within 10 seconds. The holding and quenching time is 60 seconds. After holding and quenching, the mold is released and cooled to room temperature. Then the workpiece taken out is placed in a heat treatment furnace at a temperature of 250° C. and a holding time of 40 minutes. The average cooling rate of the hot stamping and pressure quenching process is 36°C / s. Measured by phase change dilatometer, the M of this steel s point at 232°C, M f The point is 58°C.

[0056] The test results of mechanical properties show that the tensile strength of the HS-BT steel is 2079MPa, the elongation is 9.8%, and the strength-plastic product is 20374MPa·% afte...

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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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/54C21D8/00C21D6/00
Inventor 张士宏宋鸿武程明林涛
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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