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: 2012-11-07
NINGBO IRON & STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0023] It can be seen from Table 5 that the hot-rolled steel coil Q345 has a large strength margin, low elongation, poor material comprehensive 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

[0046] 1) After the composition is designed, the molten iron is pretreated, then the converter is smelted, nitrogen and argon are switched, and the molten steel is obtained after tapping; it is supplemented before tapping, and the tapping time is 4.5min; the alloy is added before 4 / 5 tapping; Double-stop slag for tapping, 80mm thickness of slag at the station; the processing time of argon blowing at the argon station is 17 minutes;

[0047] 2) The weight percentages of the components of the molten steel after tapping are as follows: C 0.06%, Si 0.20%, Mn 1.20%, P0.010%, S 0.005%, Nb+Ti+V 0.040%, Als 0.020%, and the rest It is iron and unavoidable impurities; the molten steel is continuously cast to obtain a slab, in which the molten steel in the tundish is 25t and the liquid level is 550mm when the tundish in the first continuous casting furnace is opened; the molten steel in the tundish is 15t when the tundish is changed quickly , The liquid level is 350mm; the normal pouring ti...

Embodiment 2

[0051] 1) After the composition is designed, the molten iron is pretreated, then the converter is smelted, nitrogen and argon are switched, and the molten steel is obtained when tapping; 0 times of supplementary blowing before tapping, tapping time 6.0min; adding alloy before tapping 4 / 5; Double-stop slag for tapping, the thickness of the slag at the station is 60mm; the processing time of the argon station is 25min;

[0052] 2) The weight percentages of the components of the molten steel after tapping are as follows: C 0.07%, Si 0.25%, Mn 1.30%, P0.015%, S 0.010%, Nb+Ti+V 0.050%, Als 0.025%, and the rest It is iron and unavoidable impurities; the molten steel is continuously cast to obtain a slab, in which the molten steel in the tundish is 30t and the liquid level is 560mm when the tundish in the first continuous casting furnace is opened; the molten steel in the tundish is 18t when the tundish is changed quickly , The liquid level is 380mm; during normal pouring, the molten st...

Embodiment 3

[0056] 1) After the composition is designed, the molten iron is pretreated, then the converter is smelted, nitrogen and argon are switched, and the molten steel is obtained from the tapping; one additional blow before tapping, the tapping time is 8.0min; the alloy is added before 4 / 5 tapping; Double-stop slag for tapping, the thickness of the slag at the station is 30mm; the processing time of the argon station is 30min;

[0057] 2) The weight percentages of the components of the molten steel after tapping are as follows: C 0.08%, Si 0.30%, Mn 1.40%, P0.020%, S 0.015%, Nb+Ti+V 0.060%, Als 0.030%, and the rest It is iron and inevitable impurities; the molten steel is continuously cast to obtain slabs, in which the molten steel volume of the tundish is 28t when the tundish in the first continuous casting furnace is opened, and the liquid level is 580mm; , The liquid level is 400mm; during normal pouring, the molten steel in the tundish is 50t and the liquid level is 1000mm. When th...

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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 Q345R 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, and particularly relates to a method for producing hot-rolled steel coils. Background technique [0002] The current production of 345MPa grade series of steel coils has a high composition of C, a lot of cracks on the surface of the slab, a large margin of strength, and low plasticity and toughness. The strength margin is large, which affects the cold working performance; there is a large probability of cracks on the surface of the cast slab, which 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, product market competition Poor capacity; steel rolling adopts arbitrary rolling technology, and the product performance fluctuates in a large range, which is not conducive to the use of users. Q345 series steel coil production performance survey [0003] Table 1 Statist...

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王辉张本亮李洪鹏韦泽
Owner NINGBO IRON & STEEL
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