Method for producing hot-rolled steel coil for shipbuilding

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 coil for shipbuilding
  • Method for producing hot-rolled steel coil for shipbuilding
  • Method for producing hot-rolled steel coil for shipbuilding

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 0.90%, P0.010%, S 0.005%, Nb+Ti+V 0.040%, Als 0.020%, the rest It is iron and unavoidable impurities; the molten steel is continuously cast to obtain a slab, wherein the molten steel in the tundish is 25t and the liquid level is 550mm when the tundish is opened in the first continuous casting furnace; the molten steel in the tundish is 15t when the tundish is quickly chan...

Embodiment 2

[0052] 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; 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 1.0%, P 0.015%, S 0.009%, Nb+Ti+V 0.050%, Als 0.025%, the rest It is iron and unavoidable impurities; the molten steel is continuously cast to obtain a slab, wherein the amount of molten steel in the tundish is 30t and the liquid level is 560mm when the tundish is opened in the first furnace of continuous casting; the amount of molten steel in the tundish is 18t when the tundish is qui...

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 1.10%, P0.020%, S 0.016%, Nb+Ti+V 0.060%, Als 0.030%, the rest Iron and unavoidable impurities; the molten steel is continuously cast to obtain a slab, wherein the molten steel in the tundish is 28t and the liquid level is 580mm when the tundish is opened in the first continuous casting furnace; the molten steel in the tundish is 20t when the tundish is quickly changed , the liquid...

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Abstract

The invention relates to a method for producing a hot-rolled steel coil for shipbuilding, which comprises the following steps of: 1) designing components, pretreating molten iron, smelting in a converter, switching nitrogen and argon, and tapping to obtain molten steel; 2) performing continuous casting on the molten steel to obtain a plate blank, wherein the content of the molten steel in a continuously cast intermediate ladle is controlled to be between 8 and 15t and the liquid level is controlled to be between 200 and 350mm when the intermediate ladle is not poured; and pouring is protectedin the whole process, and the insertion depth of a long nozzle is between 300 and 400mm; 3) heating the plate blank; and 4) rolling and curling the heated plate blank. The content of C and Mn is greatly reduced through niobium microalloying by a thermo-mechanical controlled process-relaxed precipitation control (TMCP-RPC) rolling process, and production cost is reduced; the obtained grade D36 hot-rolled steel coil for shipbuilding has high plasticity and toughness, and the elongation of the hot-rolled steel coil is improved by over 8 percent; meanwhile, the welding performance of the materialis improved, and the high surface quality of a continuously cast blank is ensured.

Description

technical field [0001] The invention belongs to the field of preparation of hot-rolled steel coils, in particular to a production method of hot-rolled steel coils for shipbuilding. 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. Investigation on production perf...

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 杨云清邹阳丘祥光杨明清唐其芳张庆雨任艳张云虎
Owner NINGBO IRON & STEEL
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