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Method for producing hot rolled steel coils

A technology of hot-rolled steel coils and production methods, applied in the direction of improving process efficiency, etc., can solve the problems of poor material comprehensive performance, large strength margin, and low elongation, and achieve improved welding performance, good surface quality, and elongation Improved effect

Inactive Publication Date: 2012-07-25
NINGBO IRON & STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0024] It can be seen from Table 5 that the hot-rolled steel coil Q345 has a large strength margin, low elongation, poor overall material properties, and high Mn in the composition

Method used

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  • Method for producing hot rolled steel coils
  • Method for producing hot rolled steel coils
  • Method for producing hot rolled steel coils

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] 1) After the composition is designed, the molten iron is pretreated, then smelted in a converter, nitrogen and argon are switched, and the molten steel is obtained after tapping; the supplementary blowing is performed once before tapping, and the tapping time is 4.5 minutes; the alloy is added before tapping 4 / 5; Tapping double slag blocking, the slag thickness at the arrival station is 80mm; the whole process of argon blowing at the argon station takes 17 minutes;

[0048] 2) The weight percentages of the components of the above-mentioned molten steel after tapping are as follows: C 0.06%, Si 0.20%, Mn 0.60%, P 0.010%, S 0.005%, Nb+Ti+V 0.040%, the rest is iron and Impurities to be avoided; the molten steel is continuously cast to obtain a slab, wherein the molten steel volume of the tundish is 25t and the liquid level is 550mm when the tundish is poured in the first continuous furnace; ;The amount of molten steel in the tundish is kept at 42t and the liquid level is 9...

Embodiment 2

[0052] 1) After the composition is designed, the molten iron is pretreated, then smelted in the converter, nitrogen and argon are switched, and the molten steel is obtained from tapping; 0 times of supplementary blowing before tapping, and the tapping time is 6.0min; the alloy is added before tapping 4 / 5; Tapping double slag blocking, the slag thickness at the arrival station is 60mm; the argon station handles the whole process of blowing argon for 25 minutes;

[0053]2) The weight percentages of the components of the above-mentioned molten steel after tapping are as follows: C 0.07%, Si 0.25%, Mn 0.70%, P 0.015%, S 0.010%, Nb+Ti+V 0.050%, the rest is iron and Impurities to be avoided; the molten steel is continuously cast to obtain a slab, wherein the tundish steel volume is 30t and the liquid level is 560mm when the tundish is poured in the first furnace of continuous casting; the tundish steel volume is 18t and the liquid level is 380mm when the tundish is quickly changed ;...

Embodiment 3

[0057] 1) After the composition is designed, the molten iron is pretreated, then smelted in the converter, nitrogen and argon are switched, and the molten steel is obtained after tapping; the supplementary blowing is performed once before tapping, and the tapping time is 8.0min; the alloy is added before tapping 4 / 5; Tapping double slag blocking, the slag thickness at the arrival station is 30mm; the whole process of argon blowing at the argon station is 30min;

[0058] 2) The weight percentages of the components of the above-mentioned molten steel after tapping are as follows: C 0.08%, Si 0.30%, Mn 0.80%, P 0.020%, S 0.015%, Nb+Ti+V 0.065%, and the rest are iron and Avoided impurities; the molten steel is continuously cast to obtain a slab, wherein the tundish steel volume is 28t and the liquid level is 580mm when the tundish is poured in the first continuous furnace; the tundish steel volume is 20t and the liquid level is 400mm when the tundish is quickly changed ;The amount...

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Abstract

The invention relates to a method for producing hot rolled steel coils. The method comprises the following steps: 1) designing the components, pretreating molten iron, then carrying out converter smelting, carrying out nitrogen / argon changing over and carrying out tapping to obtain molten steel; 2) continuously casting the molten steel to obtain slabs, controlling the weight of the molten steel in the tundish to be 8-15t when casting of the continuous casting tundish is stopped, ensuring the liquid level to be 200-350mm; carrying out protective casting in the whole course and ensuring the insertion depth of the long nozzle to be 300-400mm; 3) heating the slabs; and 4) finally rolling and curling the heated slabs, thus obtaining the hot rolled steel coils. The method has the following beneficial effects: the TMCP (thermo-mechanical control process)+RPC (relaxation-precipitation-controlling phase transformation) rolling processes are adopted and the contents of C and Mn are substantially reduced by utilizing micro-niobium treatment, thus reducing the production cost; and the Q345B hot rolled steel coils obtained by the method have excellent plasticity and toughness, the elongation of the hot rolled steel coils is improved by more than 8%, and at the same time, the welding property of the materials is improved and good surface quality of the continuous casting slabs is ensured.

Description

technical field [0001] The invention belongs to the field of steel coil preparation, in particular to a production method of hot-rolled steel coils. Background technique [0002] The current production of steel coils with a yield strength of 345MPa is high in the composition of each steel plant, with many cracks on the surface of the billet, a large margin of strength, and low plasticity and toughness. Large strength margin affects cold working performance; there is a high probability of cracks on the surface of the billet and cannot be directly installed, which is not conducive to energy saving and emission reduction; high C content, poor welding performance; high Mn content in steel, high production costs, and product market competition The ability is poor; the steel rolling adopts any rolling process, and the performance of the product fluctuates in a large range, which is not conducive to the use of users. [0003] Investigation on production performance of Q345 series ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/04C22C33/04C21D8/02
CPCY02P10/20
Inventor 杨云清邹阳贾国军丘祥光唐小勇朱凯吴伟娟张军霞
Owner NINGBO IRON & STEEL
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