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Technique for producing 500MPa level high-strength quake-proof reinforcing steel bar

An anti-seismic reinforcement and production process technology, applied in the field of low-alloy steel production process, can solve the problems of adding water-piercing equipment, poor shock resistance, and poor welding performance, and achieve good promotion and application prospects, improved performance indicators, and good welding performance.

Inactive Publication Date: 2010-07-14
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] At present, most low-alloy steels are designed with carbon-manganese steel-based components, manganese-based and silicon-based iron alloys are used for alloying manganese and silicon elements, vanadium-iron or vanadium-nitrogen alloys are used for vanadium microalloying, and niobium-iron alloys are used for niobium microalloying. Chemical, its main components control [Mn] between 1.2-1.6%, [Si] between 0.40-0.60%, [C] between 0.17-0.25%, [V] between 0.06-0.12% , [Nb] is controlled between 0.04-0.09%, yield strength (Rel) ≥ 500MPa, tensile strength ≥ 630MPa, reduction of area (A) ≥ 16%, mainly relying on carbon, manganese and silicon solid solution strengthening and vanadium and Niobium precipitation strengthening, this steel has the following problems: ①Silo-manganese and carbon content is high, and the alloy cost increases; ②Element segregation is easy to occur during solidification and cooling; ③High carbon equivalent has poor welding performance, vanadium and High niobium content and high alloy cost; ④ prone to inconspicuous yield and mixed crystal phenomenon; ⑤ poor shock resistance
Another method is to control the composition to the lower limit, and use low-temperature large-deformation rolling to produce ultra-fine-grained steel, and the alloy composition can be reduced, but the disadvantages of this method are that ① the capacity of the rolling mill needs to be greatly increased; Conventional welding cannot be used, otherwise the strength of the steel bar in the welding zone will be greatly reduced
Another method is to control the composition to the lower limit, and use forced cooling after rolling, and the alloy composition can also be greatly reduced, but the disadvantages are: ① need to increase water penetration equipment and increase investment; ② the performance of steel bars fluctuates greatly, and the aging phenomenon is serious; ③ Welding performance is poor; ④The steel bar is easy to corrode and the shock resistance is poor

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] High-strength anti-seismic steel bars are smelted on a 100-ton oxygen top-bottom double-blown converter. Blast furnace molten iron, scrap steel and pig iron are sequentially added to the converter for smelting with oxygen blowing, and lime is added as a slagging material. After 5 minutes of oxygen blowing into the converter, reducing manganese oxide is added. For pellets, blow oxygen at the top for 4 minutes, and blow nitrogen at the bottom for 4 minutes at the same time, [C]=0.16% and [Mn]=0.22% in the molten steel at the end point; add reduced vanadium oxide pellets and reduced niobium oxide at the later stage of smelting, and blow oxygen at the top for 5.5 min, and at the same time blow bottom gas for 5.5 min, so that [V] = 0.016%, [Nb] = 0.045%, [S] = 0.035%, [P] = 0.031%, and the molten steel temperature = 1685 °C at the end of smelting;

[0027] In the early stage of tapping, add silicon-manganese, ferrosilicon alloy, silicon carbide and carbon powder into the ladl...

Embodiment 2

[0031]High-strength anti-seismic steel bars are smelted on a 60-ton oxygen top-bottom double-blown converter. Blast furnace molten iron, scrap steel and pig iron are sequentially added to the converter for smelting with oxygen blowing, and slag-making materials such as lime are added. After oxygen blowing into the converter for 8 minutes, reductive oxidation is added. Manganese pellets, top blowing oxygen for 6 minutes, and bottom blowing for 6 minutes at the same time, [C]=0.19% and [Mn]=0.29% in molten steel at the end point; adding reduced vanadium oxide pellets and reduced niobium oxide in the later stage of smelting, top blowing oxygen for 2 minutes , while bottom blowing for 2 minutes, at the end point molten steel [V] = 0.047%, [Nb] = 0.015%, [S] = 0.028%, [P] = 0.038%, temperature = 1693 ° C tapping;

[0032] Add silicon-manganese and ferrosilicon alloy, silicon carbide and carbon powder to the ladle in the early stage of tapping, [C]=0.25%, [Mn]=0.70%, [Si]=0.41% in mo...

Embodiment 3

[0035] High-strength anti-seismic steel bars are smelted on a 120-ton oxygen top-bottom double-blown converter. Blast furnace molten iron, scrap steel and pig iron are sequentially added to the converter for smelting with oxygen blowing, and slagging materials such as lime are added. After 2 minutes of oxygen blowing into the converter, reductive oxidation is added. For manganese pellets, top-blown oxygen for 3 minutes and bottom-blown for 3 minutes at the same time, [C]=0.17% and [Mn]=0.38% in molten steel at the end; adding reduced vanadium oxide pellets and reduced niobium oxide in the later stage of smelting, and top-blown oxygen for 4 minutes , while bottom blowing for 4 minutes, the end point molten steel [V] = 0.033%, [Nb] = 0.031%, [S] = 0.036%, [P] = 0.032%, temperature = 1691 ° C tapping;

[0036] Add silicon manganese and ferrosilicon alloy, silicon carbide and carbon powder to the ladle in the early stage of tapping, [C]=0.21%, [Mn]=1.370%, [Si]=0.56% in molten stee...

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Abstract

The invention discloses a technique for producing 500MPa level high-strength quake-proof reinforcing steel bar. Nitrogen is blown into molten steel in a steel ladle by a microwave field in the process of steel taping, [N] in the molten steel ranges from 0.08% to 0.012%; reducible manganese oxide pellets are added in the metaphase of smelting; reducible vanadium oxide and niobium oxide pellets are added in the later stage of smelting; manganese family alloy, silicon family alloy and carburant are added in the process of steel taping, [Mn] in the molten steel ranges from 0.60% to 1.40%, [Si] in the molten steel ranges from 0.20% to 0.60%; ferrovanadium and ferroniobium are added in the process of steel taping to fine tunes vanadium and niobium in the steel, [V] in the steel ranges from 0.02% to 0.055%, [Nb] ranges from 0.02% to 0.055%; molten steel is cast into steel billets by a conticaster, the steel billets are heated by a heating furnace, heating temperature is between 1050 DEG C and 1250 DEG C, start rolling temperature is between 950 DEG C and 1150 DEG C, finishing temperature is between 950 DEG C and 1050 DEG C, and cooling speed after rolling is between 15 DEG C / s and 500 DEG C / s; Rel of the reinforcing steel bar produced by the method is between 530MPa and 560MPa, Rm is between 660MPa and 730MPa, A is between 18% and 25%, Rm / Rel is between 1.30 and 1.45, ageing lasts for three months, undulating quantity of Rel and Rm is less than 15MPa, welding performance is good, and popularization and application prospects are promising.

Description

technical field [0001] The invention relates to a production process of low-alloy steel, in particular to a production process of 500MPa high-strength anti-seismic steel bars. Background technique [0002] At present, most low-alloy steels are designed with carbon-manganese steel-based components, manganese-based and silicon-based iron alloys are used for alloying manganese and silicon elements, vanadium-iron or vanadium-nitrogen alloys are used for vanadium microalloying, and niobium-iron alloys are used for niobium microalloying. Chemical, its main components control [Mn] between 1.2-1.6%, [Si] between 0.40-0.60%, [C] between 0.17-0.25%, [V] between 0.06-0.12% , [Nb] is controlled between 0.04-0.09%, yield strength (Rel) ≥ 500MPa, tensile strength ≥ 630MPa, reduction of area (A) ≥ 16%, mainly relying on carbon, manganese and silicon solid solution strengthening and vanadium and Niobium precipitation strengthening, this steel has the following problems: ①Silo-manganese and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/12C22C33/04C21D8/08
Inventor 吴光亮李一为
Owner CENT SOUTH UNIV
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