High-strength hot-rolled reinforcement bar of 730 MPa level, and production technology thereof

A production process and steel bar technology, applied in the field of 730MPa high-strength hot-rolled steel bar and its production process, can solve the problems of difficulty in guaranteeing the yield platform and low yield strength of hot-rolled steel bar, avoid excessive corrosion rate and hardness, and evenly extend High rate, anti-hysteresis fracture resistance effect

Active Publication Date: 2015-04-15
江苏森林建筑新材料股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The yield strength of existing hot-rolled steel bars is relatively low. It is very difficult to make the yield strength of hot-rolled steel bars reach such a high strength as 730Mpa and above, and the strength is so high that it is difficult to guarantee the yield platform. Strength may be expressed as a 0.2% strain versus strength

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] The 730MPa grade high-strength hot-rolled steel bar in this embodiment has the following chemical composition by weight: C: 0.48%, Cr: 1.1%, Mn: 0.75%, Mo: 0.25%, Si: 0.21%, S: 0.025%, P: 0.03%, N: 0.025%, the balance is Fe.

[0035] The production technology of the 730MPa level high-strength hot-rolled steel bar of the present embodiment is carried out according to the following steps:

[0036] (1) Put the smelted steel bar into the heating furnace and heat it to 1200°C, then quickly cool the steel bar to 570°C through the first online cooling process, and then quench it with water or quenching liquid in the quenching device for 9 seconds, and then pass through The tempering heating furnace is heated to 660°C for tempering, and then cooled to normal temperature through the second cooling process;

[0037] The first cooling process: use water cooling to cool the steel bars to 570°C at a cooling rate of 12°C / s;

[0038] The second cooling process: the combination of wa...

Embodiment 2

[0045] The 730MPa grade high-strength hot-rolled steel bar in this embodiment has the following chemical composition by weight: C: 0.51%, Cr: 0.8%, Mn: 1.0%, Mo: 0.15%, Si: 0.15%, S: 0.015%, P: 0.025%, N: 0.015%, and the balance is Fe.

[0046] The production technology of the 730MPa level high-strength hot-rolled steel bar of the present embodiment is carried out according to the following steps:

[0047] (1) Put the smelted steel bar into the heating furnace and heat it to 1100°C, then quickly cool the steel bar to 580°C through the first online cooling process, and then quench it with water or quenching liquid in the quenching device for 10 seconds, and then pass through The tempering heating furnace is heated to 600°C for tempering, and then cooled to normal temperature through the second cooling process;

[0048] The first cooling process: use water cooling to cool the steel bars to 580 °C at a cooling rate of 13 °C / s;

[0049] The second cooling process: the combinatio...

Embodiment 3

[0056] The 730MPa grade high-strength hot-rolled steel bar in this embodiment has the following chemical composition by weight: C: 0.53%, Cr: 0.9%, Mn: 0.85%, Mo: 0.2%, Si: 0.3%, S: 0.013%, P: 0.015%, N: 0.012%, and the balance is Fe.

[0057] The production technology of the 730MPa level high-strength hot-rolled steel bar of the present embodiment is carried out according to the following steps:

[0058] (1) Put the smelted steel bar into the heating furnace and heat it to 1010°C, then quickly cool the steel bar to 590°C through the first online cooling process, and then quench it with water or quenching liquid in the quenching device for 11 seconds, and then pass through The tempering heating furnace is heated to 520°C for tempering, and then cooled to normal temperature through the second cooling process;

[0059] The first cooling process: use water cooling to cool the steel bars to 590 °C at a cooling rate of 14 °C / s;

[0060] The second cooling process: the combination...

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Abstract

The invention relates to a steel bar and its production process, which is a 730MPa grade high-strength hot-rolled steel bar and its production process. The chemical composition in weight percentage is: C: 0.48-0.53%, Cr: 0.8-1.1%, Mn: 0.75- 1.0%, Mo: 0.15-0.25%, Si: 0.15-0.3%, S: <0.035%, P: <0.035%, N: <0.035%, and the balance is Fe. The steel bar yield strength of the present invention can reach 730Mpa, has the advantages of high strength, good ductility, strong hysteresis fracture resistance, steel saving, low relaxation, easy welding, good upsetting performance, etc., and can fully dissolve carbides and evenly diffuse, It avoids the precipitation of carbides between grains and causes excessive intergranular corrosion and pitting corrosion.

Description

technical field [0001] The invention relates to a steel bar and its production process, in particular to a 730MPa high-strength hot-rolled steel bar and its production process. Background technique [0002] Hot-rolled steel bars are finished steel bars that have been hot-rolled and naturally cooled. They are made of low-carbon steel and ordinary alloy steel at high temperatures. They are mainly used for reinforcement of reinforced concrete and prestressed concrete structures. They are used in civil engineering One of the most widely used steel varieties. Hot-rolled steel bars are graded according to the standard value of yield strength and are divided into four grades: [0003] HPB235 (Q235), the standard value of the yield strength of the steel bar is 235MPa, the diameter is 8-20mm, and the elastic modulus is 210GPa. [0004] HRB335 (20MnSi), the standard value of the yield strength of the steel bar is 335MPa, the diameter is 6-50mm, and the elastic modulus is 200GPa. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/22C21D11/00
Inventor 姚圣法吴海洋
Owner 江苏森林建筑新材料股份有限公司
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