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690MPa-grade low-yield-ratio thin-gauge weather-proof bridge steel and manufacturing method thereof

A technology with a low yield ratio and a manufacturing method, applied in the field of weathering steel, can solve the problems of increasing the cost of steel grades, and achieve the effects of good performance uniformity, low comprehensive production cost, and excellent shape.

Active Publication Date: 2021-05-25
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] The Chinese patent application with the publication number CN110468349A provides an earthquake-resistant high-strength weather-resistant bridge steel plate Q690qENHZ35 and its production method. Its components and weight percentages are: C: 0.05-0.12%, Si: 0.08-0.25%, Mn: 0.09~1.45%, P≤0.012%, S≤0.003%, Cu: 0.25~0.35%, Ni: 0.80~1.85%, Mo: 0.25~0.80%, Cr: 0.50~1.0%, V: 0.040~0.080% , Ti: 0.010~0.020%, B: 0.0008~0.00135%, and the rest are Fe and unavoidable impurities; pre-quenching treatment + sub-temperature quenching treatment + tempering treatment is adopted, but pre-quenching treatment is added, resulting in obvious steel cost Increase

Method used

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  • 690MPa-grade low-yield-ratio thin-gauge weather-proof bridge steel and manufacturing method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] A low-yield ratio thin-gauge weather-resistant bridge steel with a yield strength of 690MPa, the composition of which is calculated by mass percentage: C: 0.05%, Si: 0.38%, Mn: 1.70%, P: 0.010%, S: 0.0010%, Nb : 0.045%, Ti: 0.015%, Ni: 0.40%, Cu: 0.20%, Cr: 0.50%, Mo: 0.35%, Alt: 0.02%, and the balance is Fe and unavoidable impurities.

[0043] The raw materials are smelted, refined, alloyed, and treated with calcium to obtain molten steel. The slab is continuously cast on the molten steel. The thickness of the cast slab is 150 mm, and the atmospheric corrosion resistance index I is 6.1. The continuous casting slab is stacked and cooled for more than 24 hours, and the slab is heated at 1230°C, and the temperature uniformity is less than 15°C. After heating for 150 minutes, phosphorus removal is carried out, and then one-stage rolling is carried out to reach the final product thickness of 6mm, and the final rolling is 830°C. .

[0044] Laminar cooling is carried out aft...

Embodiment 2

[0047] A low-yield ratio thin-gauge weather-resistant bridge steel with a yield strength of 690MPa, the composition of which is calculated by mass percentage: C: 0.06%, Si: 0.30%, Mn: 1.56%, P: 0.010%, S: 0.0015%, Nb : 0.041%, Ti: 0.020%, Ni: 0.60%, Cu: 0.15%, Cr: 0.70%, Mo: 0.15%, Alt: 0.04%, and the balance is Fe and unavoidable impurities.

[0048] The raw materials are smelted, refined, alloyed, and treated with calcium to obtain molten steel, which is continuously cast with slabs on molten steel, and the billets with a thickness of 260mm are cast, and the atmospheric corrosion resistance index I is 6.2. The continuous casting slabs are stacked and cooled for more than 48 hours, and the slabs are soaked at 1200°C, and the temperature uniformity is less than 15°C. After heating for 260 minutes, phosphorus removal is carried out, followed by two-stage rolling. The rolling temperature in the recrystallization zone is 1070°C, the total deformation is 78%, and the thickness of ...

Embodiment 3

[0052] A low-yield ratio thin-gauge weather-resistant bridge steel with a yield strength of 690MPa, the composition of which is calculated by mass percentage: C: 0.09%, Si: 0.21%, Mn: 1.30%, P: 0.0090%, S: 0.0020%, Nb : 0.050%, Ti: 0.018%, Ni: 0.80%, Cu: 0.40%, Cr: 0.55%, Mo: 0.25%, Alt: 0.02%, and the balance is Fe and unavoidable impurities.

[0053] The raw materials are smelted, refined, alloyed, and treated with calcium to obtain molten steel. The slab is continuously cast on the molten steel, and the thickness of the cast slab is 260mm. The atmospheric corrosion resistance index I is 6.9. The slabs were stacked and cooled for more than 48 hours, and the slabs were soaked at 1180°C, and the temperature uniformity was less than 15°C. After heating for 234 minutes, phosphorus removal was carried out, followed by two-stage rolling. The rolling temperature in the recrystallization zone is 1050°C, the total deformation of the rough rolling is 72%, and the thickness of the inte...

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Abstract

The invention discloses a 690MPa-grade low-yield-ratio thin-gauge weather-proof bridge steel and a manufacturing method of the 690MPa-grade low-yield-ratio thin-gauge weather-proof bridge steel. The bridge steel is composed of, by mass, 0.05%-0.09% of C, 0.21%-0.50% of Si, 1.30%-1.70% of Mn, smaller than or equal to 0.010% of P, smaller than or equal to 0.002% of S, 0.041%-0.070% of Nb, 0.010%-0.020% of Ti, 0.15%-0.40% of Cu, 0.40%-0.80% of Ni, 0.40%-0.70% of Cr, 0.15%-0.35% of Mo, 0.02%-0.04% of Alt and the balance Fe and inevitable impurities. Through economical component design and a matched manufacturing method of controlled rolling and controlled cooling, off-line quenching and off-line tempering, the thin weather-proof bridge steel with the thickness of 6mm to 32mm and the yield strength of 690 MPa is produced, so that the bridge steel has the characteristics of low yield ratio, high low-temperature toughness, high ductility and good plate shape.

Description

technical field [0001] The invention relates to a weather-resistant steel, in particular to a weather-resistant bridge steel with a low yield strength ratio of 690 MPa and a manufacturing method thereof. Background technique [0002] With the development of large-scale steel structure bridges towards long-span, heavy-load, and fully welded structures, the requirements for the safety and reliability of bridge structures are becoming more and more stringent. This puts forward higher requirements for the designer, and also puts forward higher standards for the quality of the steel plate. It not only requires the steel plate to have high strength to meet the structural lightweight requirements, but also has excellent plasticity, low temperature toughness, weldability, Corrosion resistance, etc., to meet the working conditions of bridges with larger spans and heavier loads. The application of high-strength, high-toughness, high-plasticity, and high-weather-resistant bridge steel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/58C22C38/48C22C38/50C22C38/42C22C38/44C22C38/06C21D8/02C21D1/18
CPCC22C38/02C22C38/04C22C38/58C22C38/48C22C38/50C22C38/42C22C38/44C22C38/06C21D8/0226C21D8/0263C21D1/18C21D2211/002C21D2211/005
Inventor 王军崔强陈林恒唐春霞孟令明刘涛
Owner NANJING IRON & STEEL CO LTD
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