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Method for controlling twill on surface of thick-specification cold-rolled HSLA steel strip

A control method and thick gauge technology, applied in the field of metallurgy, can solve the problems of unsuitable elongation of the head and tail, large loss of strip steel cutting, slowing down of the annealing furnace, etc., so as to facilitate popularization and application and meet the requirements of high surface grade steel Requirements, the effect of good steel strip surface quality

Active Publication Date: 2021-11-26
SD STEEL RIZHAO CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] CN111346927A discloses a method for controlling the rolling force of a temper mill. The key point is to solve the problem that the elongation of the head or tail of the temper often occurs after the machine is stopped and started or when the next coil of strip is rolled. Problems of inappropriate shape and out of control plate shape
[0006] CN110064652B provides a method and device applied to the limit variable specification rolling of the temper mill, which mainly solves the technical problems of slowing down of the annealing furnace and large loss of strip steel cutting during the limit variable specification rolling of the temper mill

Method used

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  • Method for controlling twill on surface of thick-specification cold-rolled HSLA steel strip
  • Method for controlling twill on surface of thick-specification cold-rolled HSLA steel strip

Examples

Experimental program
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Embodiment 1

[0032] Prepare thick-gauge cold-rolled HSLA steel without twill on the surface. The grade of cold-rolled HSLA steel is HC420LA. It is obtained through smelting, continuous casting, hot continuous rolling, acid continuous rolling, and continuous annealing. The specific steps are as follows:

[0033] 1) Smelting chemical composition and mass percentage: C 0.078%, Si 0.32%, Mn 1.30%, P 0.025%, S0.007%, Als 0.039%, Nb 0.042%, N 0.003%, the rest is Fe and unavoidable impurities .

[0034] 2) Continuous acid rolling: the thickness of cold rolling is 1.8mm, the width is 1200mm, the total reduction rate of cold rolling is 64%, and the roughness Ra of the work rolls without stand is 2.7μm.

[0035] 3) Continuous annealing process: during production, the thickness difference ΔH of the steel coil before and after production is 0.1mm, the width difference ΔB is 50mm, and the yield strength difference Δσ is 40MPa; 5-15m / min, acceleration 0.5-0.8m / min / s, the tempering machine adopts small ...

Embodiment 2

[0038] Prepare thick-gauge cold-rolled HSLA steel without twill on the surface. The grade of cold-rolled HSLA steel is HC340LA. It is obtained through smelting, continuous casting, hot continuous rolling, acid continuous rolling, and continuous annealing. The specific steps are as follows:

[0039] 1) Smelting chemical composition and mass percentage: C 0.060%, Si 0.08%, Mn 0.85%, P 0.023%, S0.006%, Als 0.045%, Nb 0.032%, N 0.005%, the rest is Fe and unavoidable impurities .

[0040] 2) Continuous acid rolling: the thickness of cold rolling is 1.5mm, the width is 1700mm, the total reduction rate of cold rolling is 70%, and the roughness Ra of the work rolls of the unstand rolls is 2.5 μm.

[0041] 3) Continuous annealing process: the thickness difference ΔH of the front and rear steel coils during production is 0mm, the width difference ΔB is 120mm, and the yield strength difference Δσ is 80MPa; the temperature fluctuation ΔT in the annealing soaking section is 12-20°C, and th...

Embodiment 3

[0044] Prepare thick-gauge cold-rolled HSLA steel without twill on the surface. The grade of cold-rolled HSLA steel is HC420LA. It is obtained through smelting, continuous casting, hot continuous rolling, acid continuous rolling, and continuous annealing. The specific steps are as follows:

[0045] 1) Smelting chemical composition and mass percentage: C 0.090%, Si 0.35%, Mn 1.17%, P 0.020%, S0.009%, Als 0.060%, Nb 0.050%, N 0.004%, the rest is Fe and unavoidable impurities .

[0046] 2) Continuous acid rolling: the thickness of cold rolling is 2.0mm, the width is 1630mm, the total reduction rate of cold rolling is 63.6%, and the roughness Ra of the work rolls without stand is 3.0μm.

[0047] 3) Continuous annealing process: during production, the thickness difference ΔH of the steel coil before and after production is 0mm, the width difference ΔB is 30mm, and the yield strength difference Δσ is 0MPa; the temperature fluctuation ΔT in the annealing soaking section is 2~5℃, and th...

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Abstract

The invention discloses a method for controlling twill on the surface of a thick-specification cold-rolled HSLA steel strip. The method comprises the following steps that (1), steel comprises the chemical ingredients of, in percentage by mass, 0.060-0.090% of C, 0.05-0.40% of Si, 0.70-1.30% of Mn, 0.015-0.025% of P, less than or equal to 0.010% of S, 0.025-0.060% of Als, 0.025-0.050% of Nb, less than or equal to 0.0050% of N and the balance Fe and inevitable impurities; (2), a smelting working procedure is performed; (3), a continuous casting working procedure is performed; (4), a hot continuous rolling working procedure is performed; (5), an acid continuous rolling working procedure is performed; and (6), a continuous annealing working procedure is performed. By means of the method for controlling the twill on the surface of the thick-specification cold-rolled HSLA steel strip, the defects of the surface twill and the like caused by rolling force fluctuation during flattening due to insufficient recrystallization annealing of the steel strip and the non-uniform internal structure and performance are avoided, flattening rolling is guaranteed to be smooth and steady, obtaining of the good steel strip surface quality is facilitated, and the method is low in cost and easy to realize.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a method for controlling twill lines on the surface of thick-gauge cold-rolled HSLA steel strips. Background technique [0002] Cold-rolled HSLA steel is widely used in automotive structural parts and reinforcements due to its good strength and toughness, as well as low carbon equivalent, which is conducive to stamping and welding processing. At present, cold-rolled HSLA steel is mainly produced through continuous annealing lines. Compared with bell annealing, continuous annealing lines have the advantages of high production efficiency, uniform mechanical properties, and good surface quality. However, for the cold-rolled HSLA steel above 1.5mm, twill lines are easy to appear on the surface of the steel strip after continuous cold rolling and continuous annealing. Once there are twill lines defects, dark cracks, wrinkles or color differences are likely to occur during the stamp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/26C21D6/00C21D8/02C21D11/00C22C38/02C22C38/04C22C38/06C22C38/12
CPCC21D1/26C21D6/005C21D6/008C21D8/0205C21D8/0221C21D8/0247C22C38/02C22C38/04C22C38/06C22C38/12C21D11/00
Inventor 康华伟孙卫华汤化胜李洪翠尹翠兰侯晓英张磊王鹏孙冰丁明凯何召东冯帆
Owner SD STEEL RIZHAO CO LTD