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Method for producing hot rolled steel coils

A production method and technology for hot-rolled steel coils, applied in the field of steel coil preparation, can solve the problems of low toughness and large strength allowance, and achieve the effects of improving welding performance, good surface quality, excellent plasticity and toughness

Inactive Publication Date: 2011-07-20
NINGBO IRON & STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0026] It can be seen from Table 6 that the hot-rolled steel coil Q235B has a large strength margin and low toughness

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

[0056] 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;

[0057] 2) The weight percentages of the components of the above-mentioned molten steel after tapping are as follows: C 0.05%, Si 0.12%, Mn 0.20%, P 0.020%, S 0.010%, Als 0.034%, and the rest are iron and unavoidable impurities; 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 casting furnace; the molten steel volume is 15t and the liquid level is 350mm when the tundish...

Embodiment 2

[0061] 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;

[0062] 2) The weight percentages of the components of the above-mentioned molten steel after tapping are as follows: C 0.07%, Si 0.17%, Mn 0.30%, P 0.010%, S 0.005%, Als 0.020%, and the rest are iron and unavoidable impurities; The molten steel is continuously cast to obtain a slab, wherein the tundish molten steel volume is 30t and the liquid level is 560mm when the tundish is poured in the first continuous casting furnace; the tundish molten steel volume is 18t and the liquid level is 380mm when the tundish is quickly...

Embodiment 3

[0066] 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;

[0067] 2) The weight percentages of the components of the above-mentioned molten steel after tapping are as follows: C 0.09%, Si 0.25%, Mn 0.35%, P 0.025%, S 0.020%, Als 0.015%, and the rest are iron and unavoidable impurities; The molten steel is continuously cast to obtain a slab, wherein the amount of molten steel in the tundish is 28t and the liquid level is 580mm when the tundish is poured in the first furnace of continuous casting; The amount of molten steel in the tundish is kept at 50t, and the liquid level is...

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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 contents of C and Mn in the Q235B steel components are reduced, proper rolling and cooling control processes are adopted, the comprehensive properties of the Q235B steel are improved and the produced Q235B hot rolled steel coils have low cost and high properties.

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 currently produced series steel coils with a yield strength of 235MPa have high C in composition, many cracks on the surface of the slab, large strength margin, and low plasticity and toughness. The large strength margin affects the cold working performance; the surface of the slab has a high probability of cracks and cannot be directly installed, which is not conducive to energy saving and emission reduction; the high C content leads to poor welding performance. [0003] Investigation on the production performance of Q235B steel coil [0004] Table 1 Statistics table of Q235B thickness and performance range [0005] [0006] It can be seen from Table 1 that: [0007] The production thickness of Q235 is less than 7.5mm, the yield strength is 275-475MPa, the tensile strength is 405-595MPa, ...

Claims

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Application Information

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IPC IPC(8): C22C38/04C22C33/04C21D8/02
Inventor 杨云清邹阳丘祥光李波欧阳炜张云虎周艳娟
Owner NINGBO IRON & STEEL
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