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Production method of low-alloy complex-phase (Q and P) steel

A production method and low-alloy technology, applied in metal rolling, metal rolling, metal processing equipment, etc., can solve the problems that the performance of steel used in automobile manufacturing cannot be well satisfied, the process is cumbersome, and the energy consumption is high, and a good comprehensive The effect of mechanical properties, simplifying process flow and reducing energy consumption

Inactive Publication Date: 2010-07-14
WUHAN IRON & STEEL (GROUP) CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The Q&P steel production methods disclosed in the above technical documents and patent documents all require subsequent heat treatment after hot rolling, the process is cumbersome, the energy consumption is high, and the product steel structure is mainly martensite and retained austenite. Although the high-strength Q&P steel has high strength, its total elongation is only about 20%, and its plasticity is poor, which cannot well meet the needs of steel performance for automobile manufacturing.

Method used

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  • Production method of low-alloy complex-phase (Q and P) steel
  • Production method of low-alloy complex-phase (Q and P) steel
  • Production method of low-alloy complex-phase (Q and P) steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] The chemical composition of selected raw material steel is calculated by weight percentage: C: 0.2, Mn: 1.50, Si: 1.60, N: 0.0034, P: 0.02, S<0.0045, O<0.003, and the balance is Fe and unavoidable impurities.

[0029] The production steps are as follows:

[0030] 1) Heat the billet to 1100°C and keep it warm for 120 minutes;

[0031] 2) Then cool it to 1000°C at a rate of 5°C / s;

[0032] 3) Take 1s again -1 Rough rolling is carried out at a strain rate of 100%, and 2 passes of deformation are carried out during rough rolling, and the strain of each pass is controlled at 50%;

[0033] 4) After rough rolling, cool down to 780°C at a rate of 5°C / s (the A of this steel is measured by thermal expansion method) r3 It is 750 ℃, use Thermo-Calc software to calculate the A of this steel 3 is 863°C);

[0034] 5) Take another 50s -1 Finish rolling is carried out at a certain strain rate, and 3 passes of deformation are carried out during finish rolling, and the strain of eac...

Embodiment 2

[0040] The chemical composition of the selected raw material steel is calculated by weight percentage: C: 0.2, Mn: 1.50, Si: 0.50, Al: 1.0, and the balance is Fe and unavoidable impurities.

[0041] The production steps are as follows:

[0042] 1) Heat the billet to 1250°C and keep it warm for 5 minutes;

[0043] 2) Then cool it to 1100°C at a speed of 20°C / s;

[0044] 3) Take another 50s -1 Rough rolling is carried out at a strain rate of 20%, and 3 passes of deformation are implemented during rough rolling, and the strain of each pass is controlled to be 20%;

[0045] 4) After rough rolling, cool down to 800°C at a rate of 50°C / s (the A of this steel is measured by thermal expansion method) r3 is 780°C, use Thermo-Calc software to calculate the A of this steel 3 is 974°C);

[0046] 5) Take 1s again -1 Finish rolling at a certain strain rate, 3-pass deformation is carried out at the finishing rolling rate, and the strain of each pass is controlled at 30%;

[0047] 6) I...

Embodiment 3

[0052] The chemical composition of the selected steel grade is the same as in Example 2.

[0053] The production steps are as follows:

[0054] 1) Heat the billet to 1200°C and keep it warm for 100 minutes;

[0055] 2) Then cool it to 1050°C at a speed of 10°C / s;

[0056] 3) Take another 25s -1 Rough rolling is carried out at a strain rate of 100%. During rough rolling, 2 passes of deformation are carried out, and the strain of each pass is controlled to be 30%;

[0057] 4) After rough rolling, cool down to 800°C at a rate of 30°C / s (the A of this steel is measured by thermal expansion method) r3 is 780°C, use Thermo-Calc software to calculate the A of this steel 3 is 974°C);

[0058] 5) Take another 20s -1 The strain rate of the finish rolling is carried out, and the deformation is carried out in 3 passes during the finish rolling, and the strain amount of each pass is controlled to 25%;

[0059] 6) Immediately after finish rolling, cool to 150°C at 60°C / s;

[0060] 7...

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Abstract

The invention discloses a production method of low-alloy complex-phase (Q and P) steel. In the method, low-carbon manganese silicon steel or low-carbon manganese silicon aluminium steel is used as raw materials, and the method comprises the following steps of: heating a steel blank to 1100-1250 DEG C; keeping the temperature for 5-120 minutes, and then cooling to 1000-1100 DEG C at the speed of 5-20 DEG C / s; then roughly rolling at the strain rate of 1-50 s<-1>; then cooling to a temperature ranging from T1 to T2 at the speed of 5-50 DEG C / s, wherein T1=A3-(A3-30) DEG C, and T2=Ar3-(Ar3+10) DEG C; then finely rolling at the strain rate of 1-50 s<-1>; after the fine rolling, cooling to the temperature ranging from T3 to T4 at the speed of 40-100 DEG C / s, wherein T3 is lower than a Ms point, and T4 is higher than a Mf point; then heating to 250-450 DEG C; keeping the temperature unchanged for 3-30 minutes, and then cooling to room temperature. Experiences prove that the low-alloy complex-phase (Q and P) steel produced by using the method has higher strength, good plasticity and comprehensive mechanical property better than that of the conventional complex-phase (Q and P) steel.

Description

technical field [0001] The invention relates to steel for automobiles, in particular to a production method of low-alloy multi-phase Q&P steel. Background technique [0002] Because Q&P (quenching and partitioning) steel has high strength and good elongation, it is especially suitable for automobile body steel and structural steel, such as automobile bumper, chassis, etc., which can reduce the degree of deformation of the body steel plate. Enhance the car body's ability to resist impact and improve the safety of the car. Therefore, in recent years, all countries in the world have increased the research and development of Q&P steel. Existing studies, such as "Quenching and partitioning martensite-a novel steel heat treatment, Mater Sci Eng A, 2006, 438-440, 25" and "Characterization of the microstructure obtained by the quenching and partitioning processing in a low-carbon steel, Mater Char , 2008, 56, 16", etc., all recorded the production method of Q&P steel. The process ...

Claims

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Application Information

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IPC IPC(8): C21D8/00B21B37/74B21B37/16
Inventor 尹云洋范植金刘吉斌方芳罗国华朱丛茂陈玮
Owner WUHAN IRON & STEEL (GROUP) CORP
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