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A kind of 700mpa grade high-strength threaded steel bar and its production method

A technology of threaded steel bar and production method, which is applied in the field of metallurgy to achieve the effect of good strength and toughness matching and improving plasticity

Active Publication Date: 2020-08-28
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] At present, domestic construction steel bars generally use 400 / 500MPa grade threaded steel bars. In order to save materials and reduce costs, foreign construction steel bars have reached the 700MPa level. It can save more than 60%. my country has not issued corresponding standards, but in the long run, it is an inevitable trend to develop high-strength steel bars for construction, so it is imperative to develop high-strength steel bars

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] The chemical composition and mass percentage of the 700MPa high-strength rebar in this example are: C: 0.31%, Si: 0.80%, Mn: 1.60%, V: 0.145%, Nb: 0.010%, B: 0.0008%, P : 0.018%, S: 0.022%, N: 225ppm, the balance is Fe and unavoidable impurities.

[0030] The production method of the 700MPa grade high-strength threaded steel bar of the present embodiment comprises steelmaking, heating, rolling and heat treatment processes, and the concrete process steps are as follows:

[0031] (1) Steelmaking: The chemical composition and mass percentage of molten steel are: C: 0.31%, Si: 0.80%, Mn: 1.60%, V: 0.145%, Nb: 0.010%, B: 0.0008%, P: 0.018%, S: 0.022%, N: 225ppm, the balance is Fe and unavoidable impurities;

[0032] (2) Heating: After the billet is heated, the furnace temperature is 1100°C;

[0033] (3) Steel rolling: after the final rolling, water cooling is adopted, the water pressure is 1MPa, and the flow rate is 300M 3 / h, the steel throwing temperature on the upper c...

Embodiment 2

[0037] The chemical composition and mass percentage of 700MPa grade high-strength rebar in this example are: C: 0.26%, Si: 0.50%, Mn: 1.40%, V: 0.220%, Nb: 0.020%, B: 0.0040%, P : 0.026%, S: 0.018%, N: 350ppm, the balance is Fe and unavoidable impurities.

[0038] The production method of the 700MPa grade high-strength threaded steel bar of the present embodiment comprises steelmaking, heating, rolling and heat treatment processes, and the concrete process steps are as follows:

[0039] (1) Steelmaking: The chemical composition and mass percentage of molten steel are: C: 0.26%, Si: 0.50%, Mn: 1.40%, V: 0.220%, Nb: 0.020%, B: 0.0040%, P: 0.026%, S: 0.018%, N: 350ppm, the balance is Fe and unavoidable impurities;

[0040] (2) Heating: After the billet is heated, the furnace temperature is 1200°C;

[0041] (3) Steel rolling: after the final rolling, water cooling is adopted, the water pressure is 3MPa, and the flow rate is 900M 3 / h, the steel throwing temperature on the upper...

Embodiment 3

[0045]The chemical composition and mass percentage of 700MPa high-strength rebar in this example are: C: 0.29%, Si: 0.66%, Mn: 1.50%, V: 0.190%, Nb: 0.015%, B: 0.0025%, P : 0.031%, S: 0.028%, N: 300ppm, the balance is Fe and unavoidable impurities.

[0046] The production method of the 700MPa grade high-strength threaded steel bar of the present embodiment comprises steelmaking, heating, rolling and heat treatment processes, and the concrete process steps are as follows:

[0047] (1) Steelmaking: The chemical composition and mass percentage of molten steel are: C: 0.29%, Si: 0.66%, Mn: 1.50%, V: 0.190%, Nb: 0.015%, B: 0.0025%, P: 0.031%, S: 0.028%, N: 300ppm, the balance is Fe and unavoidable impurities;

[0048] (2) Heating: After the billet is heated, the furnace temperature is 1150°C;

[0049] (3) Steel rolling: after the final rolling, water cooling is adopted, the water pressure is 2MPa, and the flow rate is 800M 3 / h, the steel throwing temperature on the upper coolin...

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Abstract

The invention discloses a 700MPa grade high strength threaded reinforcing steel bar and a production method. The high strength threaded reinforcing steel bar contains the chemical components in percentage by mass: 0.26-0.31% of C, 0.50-0.80% of Si, 1.40-1.60% of Mn, 0.140-0.220% of V, 0.010-0.020% of Nb, 0.0008-0.0040% of B, less than or equal to 0.040% of P, less than or equal to 0.040% of S, 200-350ppm of N and the balance Fe and inevitable impurities. The production method comprises the following steps: steelmaking; heating; steel rolling; and thermal treatment. An annular tempered structure is formed on the surface of the reinforcing steel bar and a ferrite and pearlitic structure is formed inside. The strength and toughness are matched well. The yield strength Rel of a product is greater than or equal to 700MPa, the tensile strength Rm is greater than or equal to 850MPa, the percentage elongation after fracture A is greater than or equal to 14%, and the maximal force percentage oftotal elongation Agt is greater than or equal to 7.5%.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a 700MPa grade high-strength threaded steel bar and a production method. Background technique [0002] At present, domestic construction steel bars generally use 400 / 500MPa grade threaded steel bars. In order to save materials and reduce costs, foreign construction steel bars have reached the 700MPa level. It can save more than 60%. my country has not issued corresponding standards, but in the long run, the development of high-strength steel bars for construction is an inevitable trend, so the development of high-strength steel bars is imperative. Invention content: [0003] The technical problem to be solved by the present invention is to provide a 700MPa high-strength threaded steel bar and its production method. [0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a 700MPa grade high-strength thre...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/12C21D8/08
CPCC21D8/065C21D8/08C22C38/002C22C38/02C22C38/04C22C38/12
Inventor 褚文龙王立军张俊粉张春雷翁玉娟刘毅
Owner HEBEI IRON AND STEEL
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