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A continuous annealing method for 780mpa micro-alloyed dual-phase steel

A technology of micro-alloying and dual-phase steel, which is applied in furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problems of micro-alloying dual-phase steel failure, lower production efficiency, and higher process control requirements, so as to reduce strength fluctuations, Satisfies forming requirements and has excellent elongation

Active Publication Date: 2022-04-05
MAANSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the inventors of the present application have found that the microalloyed dual-phase steel often does not have the cold-rolled fibrous structure described in Patent Document 1, and the strength fluctuations described in Patent Document 1 are reduced by the thickness of the annealing temperature and the strip speed. Alloyed dual phase steels will fail significantly
Secondly, the measures adopted in Patent Document 1, such as large reduction of the finishing stand at the beginning and end of rolling and slow cooling of the hot-rolling insulation cover, can reduce the strength fluctuation of the micro-alloyed dual-phase steel to a certain extent, but cannot fundamentally solve the problem
Thirdly, the measures described in Patent Document 1 have high requirements for process control, and the slow cooling of the hot-rolled insulation cover will also reduce production efficiency

Method used

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  • A continuous annealing method for 780mpa micro-alloyed dual-phase steel
  • A continuous annealing method for 780mpa micro-alloyed dual-phase steel
  • A continuous annealing method for 780mpa micro-alloyed dual-phase steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] 1) Carry out uncoiling and cleaning, the thickness of strip steel raw material is 1.2mm, and the length is 1739m;

[0039] 2) Carry out preheating, the temperature is controlled at 170 ℃;

[0040] 3) Heating, the heating rate is 2.72-2.83°C / s, the initial temperature is set to 820°C, the strip length 1 / 7 is set to 810°C, and the strip length 5 / 7 is set to 820°C;

[0041] 4) Perform soaking, the holding time is 89.2S, the initial temperature is set to 820°C, the strip length 1 / 7 is set to 810°C, and the strip length 5 / 7 is set to 820°C;

[0042] 5) Perform slow cooling, the slow cooling rate is 12.0-16.5°C / s, the initial temperature is set to 680°C, the strip length 1 / 7 is set to 690°C, and the strip length 5 / 7 is set to 680°C ;

[0043] 6) Carry out rapid cooling I, the temperature is controlled at 485°C, and the rapid cooling rate is 115-128°C / s;

[0044] 7) Carry out rapid cooling II, the temperature is controlled at 300°C, and the rapid cooling rate is 36-39°C / s; ...

Embodiment 2

[0051] 1) Carry out decoiling and cleaning, the thickness of the rolled hard coil is 1.6mm, and the length is 1364m.

[0052] 2) Carry out preheating, the temperature is controlled at 170 ℃;

[0053] 3) Heating, the heating rate is 2.31-2.42°C / s, the initial temperature is set to 810°C, the strip length 1 / 6 is set to 800°C, and the strip length 4 / 6 is set to 810°C;

[0054] 4) Perform soaking, the holding time is 111.5S, the initial temperature is set to 810°C, the strip length 1 / 6 is set to 800°C, and the strip length 4 / 6 is set to 810°C;

[0055] 5) Perform slow cooling, the slow cooling rate is 9.0-13.5°C / s, the initial temperature is set to 670°C, the strip length 1 / 6 is set to 680°C, and the strip length 4 / 6 is set to 670°C ;

[0056] 6) Carry out rapid cooling Ⅰ, the temperature is controlled at 455°C, and the rapid cooling rate is 107-115°C / s;

[0057] 7) Carry out rapid cooling II, the temperature is controlled at 290°C, and the rapid cooling rate is 25-28°C / s;

[...

Embodiment 3

[0064] 1) Carry out uncoiling and cleaning, the thickness of the rolled hard coil is 2.0mm, and the length is 980m;

[0065] 2) Carry out preheating, the temperature is controlled at 170 ℃;

[0066] 3) Heating, the heating rate is 1.93-2.01°C / s, the initial temperature is set to 800°C, the strip length 1 / 6 is set to 790°C, and the strip length 4 / 6 is set to 800°C;

[0067] 4) Perform soaking, the holding time is 121.6S, the initial temperature is set to 800°C, the strip length 1 / 6 is set to 790°C, and the strip length 4 / 6 is set to 800°C;

[0068] 5) Perform slow cooling, the slow cooling rate is 9.0-11.5°C / s, the initial temperature is set to 660°C, the strip length 1 / 6 is set to 670°C, and the strip length 4 / 6 is set to 660°C ;

[0069] 6) Carry out rapid cooling I, the temperature is controlled at 470°C, and the rapid cooling rate is 82.5-92.0°C / s;

[0070] 7) Carry out rapid cooling II, the temperature is controlled at 290°C, and the rapid cooling rate is 24.0-28.0°C / s;...

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Abstract

The invention discloses a continuous annealing method for 780MPa grade microalloyed dual-phase steel. The invention adopts a "U-shaped" control strategy for the heating temperature and soaking temperature, a "∩-type" control strategy for the slow cooling temperature, and a "∩" control strategy for the rapid cooling section. The segmental cooling strategy of rapid cooling Ⅰ and rapid cooling Ⅱ reduces the strength fluctuation of the product and improves the local forming performance of the product. The strength difference in the inner head of the obtained product roll does not exceed 40MPa, and the elongation after breaking is 16-23%. The hole expansion rate is not lower than 20%. The method of the invention is simple and effective, and conforms to the actual production line of a continuous annealing unit.

Description

technical field [0001] The invention relates to the technical field of metallurgical plate production, in particular to a continuous annealing method for micro-alloyed dual-phase steel with a tensile strength of 780 MPa. Background technique [0002] Dual-phase steel occupies a very important position in the automotive steel system due to its excellent strength-plasticity matching. With the continuous development of automobile lightweight, the structure of dual-phase steel parts is becoming more and more complex, and the forming methods are becoming more and more diversified. In addition to traditional deep drawing and bulging, there are also flanging and bending. put forward higher requirements. At the same time, in the application scenario of industrialized mass production, the market prefers products with high homogeneity, which puts forward higher requirements for the performance stability of dual-phase steel. [0003] In actual production, cold-rolled dual-phase steel...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D1/26C21D9/52C21D11/00
CPCC21D1/26C21D9/52C21D11/00C21D2211/005C21D2211/008C21D2211/002
Inventor 郑笑芳葛鑫涛唐东东詹华崔磊范启庆胡笛朱彪顾斌
Owner MAANSHAN IRON & STEEL CO LTD
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