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Nb-Ti-N micro-alloyed hot-rolled ribbed steel bar and production method thereof

A hot-rolled ribbed steel bar and micro-alloying technology, which is applied in the field of steel bar preparation, can solve problems such as transverse cracks on the surface of the slab, increased production costs, warped steel bar surface, etc., to reduce surface cracks, improve straightening temperature, and composition easy effect

Active Publication Date: 2020-04-21
WUHU XINXING DUCTILE IRON PIPES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, niobium microalloying produces HRB400, the stress action in continuous casting production is likely to cause defects such as transverse cracks on the surface of the slab, and defects such as warping and folding on the surface of steel bars
Moreover, the production of 400MPa-grade steel bars using a single vanadium, niobium or vanadium-niobium composite microalloying technology will increase production costs to a certain extent and seriously affect corporate profits

Method used

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  • Nb-Ti-N micro-alloyed hot-rolled ribbed steel bar and production method thereof
  • Nb-Ti-N micro-alloyed hot-rolled ribbed steel bar and production method thereof
  • Nb-Ti-N micro-alloyed hot-rolled ribbed steel bar and production method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] A Nb-Ti-N microalloyed hot-rolled ribbed steel bar, including the following chemical composition in weight percentage: C0.24%, Si0.46%, Mn1.29%, Nb0.013%, Ti0.008%, N0 .0070%, P≤0.030%, S≤0.015% and unavoidable impurities.

[0030] Its production process includes converter smelting, nitrogen blowing, refining, continuous casting and rolling;

[0031] Wherein, the converter smelting process adopts high-strength supplementary blowing, the control end point [C] is 0.11%, the end point temperature of tapping is 1635°C, and silicon-manganese, ferrosilicon, and niobium are evenly added to the steel flow during the 1 / 3 process of putting steel Alloying the ferroalloy, and adding 500kg of lime and 300kg of refining slag / furnace in the late stage of tapping, nitrogen blowing and stirring are carried out throughout the whole process, the flow of nitrogen gas is firstly blown strongly and then weakly blown, the flow rate is reduced from 750NL / min to 220NL / min, and the time is 5min...

Embodiment 2

[0036] A Nb-Ti-N microalloyed hot-rolled ribbed steel bar, including the following chemical composition in weight percentage: C0.23%, Si0.47%, Mn1.31%, Nb0.014%, Ti0.010%, N0 .0075%, P≤0.035%, S≤0.020% and unavoidable impurities.

[0037] Its production process includes converter smelting, nitrogen blowing, refining, continuous casting and rolling;

[0038] Wherein, the converter smelting process adopts high-strength supplementary blowing, the control end point [C] is 0.10%, the end point temperature of tapping is 1640°C, and silicomanganese, ferrosilicon, and niobium are evenly added to the steel flow during the 1 / 3 process of putting steel The iron alloy is alloyed, and the ladle is added with 500Kg of lime and 300Kg of refining slag / furnace. The whole process is carried out with nitrogen blowing and stirring. The nitrogen blowing at the bottom is 7 minutes, and the flow rate is 57NL / min.

[0039] In the refining furnace process, 46kg of ferrotitanium is added in the later...

Embodiment 3

[0043] A Nb-Ti-N microalloyed hot-rolled ribbed steel bar, including the following chemical components in weight percentage: C0.25%, Si0.46%, Mn1.31%, Nb0.015%, Ti0.009%, N0 .0082%, P≤0.024%, S≤0.017% and unavoidable impurities.

[0044] Its production process includes converter smelting, nitrogen blowing, refining, continuous casting and rolling;

[0045] Wherein, the converter smelting process adopts high-strength supplementary blowing, the control end point [C] is 0.11%, the end point temperature of tapping is 1635°C, and silicon-manganese, ferrosilicon, and niobium are evenly added to the steel flow during the 1 / 3 process of putting steel The iron alloy is alloyed, and the ladle is added with 500kg of lime and 300kg of refining slag / furnace. The whole process is carried out with nitrogen blowing and stirring. Bottom blowing nitrogen is 5min, flow rate is 55NL / min.

[0046] In the refining furnace process, 45kg of ferrotitanium is added in the later stage of refining, and...

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Abstract

The invention discloses an Nb-Ti-N micro-alloyed hot-rolled ribbed steel bar and a production method thereof. The Nb-Ti-N micro-alloyed hot-rolled ribbed steel bar comprises the following chemical components in percentage by weight: 0.22%-0.25% of C, 0.40%-0.60% of Si, 1.25%-1.35% of Mn, 0.012%-0.018% of Nb, 0.005%-0.015% of Ti, 0.0060%-0.0090% of N, P less than or equal to 0.045%, S less than orequal to 0.045%, and inevitable impurities. In the production process, converter tapping is subjected to bottom blowing of nitrogen, molten steel N and Nb are increased to be compounded to form NbN, technological parameters in the rolling process are controlled to enable grain boundary precipitation to achieve a precipitation strengthening effect, the strength is improved, and it is guaranteed that the mechanical property is qualified; and the straightening temperature in the continuous casting process is increased to 1000 DEG C or above, casting blank surface cracks caused by a third brittlearea are avoided, and various properties of the Nb-Ti-N micro-alloyed hot-rolled ribbed steel bar obtained through the method can meet the requirements of GB1499.2-2018.

Description

technical field [0001] The invention belongs to the technical field of steel bar preparation, and in particular relates to a Nb-Ti-N microalloyed hot-rolled ribbed steel bar and a production method thereof. Background technique [0002] The 400MPa grade HRB400 hot-rolled ribbed steel bar is an important material in the concrete structure of engineering buildings. Since 2005, the market demand for HRB400 steel bars has been increasing, which has led to a rapid expansion of the production scale of HRB400 steel bars and a substantial increase in output. Due to the use of V microalloying technology in the production of HRB400 steel bars, the price of vanadium nitrogen has risen sharply. Due to the increase in the price of vanadium nitrogen, the cost of producing HRB400 steel bars for enterprises has increased, and their profits have decreased. [0003] In order to reduce the cost of smelting alloys, domestic steel mills have embarked on the production of niobium instead of vana...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/12C22C38/14C22C33/04C21D8/08C21C7/072C21C7/00
CPCC21C7/0006C21C7/0056C21C7/072C21D8/065C21D8/08C22C33/04C22C38/001C22C38/02C22C38/04C22C38/12C22C38/14
Inventor 陶群南杨伟勇汪春梅黄雁左小坦赵立王吾磊
Owner WUHU XINXING DUCTILE IRON PIPES
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