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Polygonal ferrite-acicular ferrite two-phase steel plate/belt and production method thereof

A polygonal ferrite and acicular ferrite technology, which is applied in the direction of temperature control, etc., can solve the problems of poor impact toughness of dual-phase steel, softening of welds, use restrictions, poor welding performance, etc., and achieves large plastic deformation capacity, high Low temperature toughness level, low cost effect

Active Publication Date: 2013-06-12
CENT IRON & STEEL RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the use of ferritic-martensitic dual-phase steel in welded structural parts is limited due to poor welding performance; However, a series of problems such as poor impact toughness and weld softening of ferritic and bainitic dual-phase steels have not been resolved.
If the technical route of ferritic bainite dual-phase steel is still adopted, it will be difficult to ensure the uniformity of structure and performance on the thickness section of thick gauge steel plates, and it will be difficult to solve the problems of impact toughness and fracture toughness

Method used

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  • Polygonal ferrite-acicular ferrite two-phase steel plate/belt and production method thereof
  • Polygonal ferrite-acicular ferrite two-phase steel plate/belt and production method thereof
  • Polygonal ferrite-acicular ferrite two-phase steel plate/belt and production method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] "Fine-grained polygonal ferrite + acicular ferrite" dual-phase structure steel plate, its composition raw materials are calculated in terms of mass percentage: C: 0.05wt%, Si: 0.3 wt%, Mn: 1.5wt%, Nb: 0.045 wt% %, Mo: 0.12 wt%, P: 0.01 wt%, S: 0.0020 wt%, the balance is Fe and unavoidable impurities, which are smelted in a converter and continuously cast into a 300mm billet.

[0029] The cast slab is heated at 1200°C, the heat preservation period is more than 2 hours, the starting rolling temperature is 1100°C, the rough rolling and finishing rolling temperature is 980°C, the cumulative deformation at this temperature is 32%, the thickness of the intermediate billet is 140mm, and the finishing rolling is carried out at 930°C. 790°C, the thickness of the finish-rolled exit steel plate is 37mm; after air cooling to 740°C, start cooling to 500°C at a cooling rate of 15°C / S, and finally air cooling to room temperature.

[0030] After testing, the microstructure type of the ...

Embodiment 2 and Embodiment 3

[0035] "Fine-grained polygonal ferrite + acicular ferrite" dual-phase structure hot-rolled steel strip, the composition of raw materials in terms of mass percentage is: C: 0.08wt%, Si: 0.6wt%, Mn: 1.4wt%, Nb : 0.03 wt%, Mo: 0.1 wt%, P: 0.01 wt%, S: 0.0020 wt%, the balance is Fe and unavoidable impurities, smelted by converter, continuous casting into 200mm billet.

[0036]The cast slab is heated at 1200°C, the holding period is more than 2 hours, the starting rolling temperature is 1100°C, the rough rolling and finishing rolling temperature is 1020°C, the finishing rolling is carried out at 920°C, the finishing rolling temperature is 820°C, the thickness of the finishing rolling exit steel strip is 6mm; After the rolling mill, first accelerate cooling to 710°C, then air-cool for 8S and 15S respectively, and then start to cool at a cooling rate of 15°C / S to 500°C for coiling.

[0037] After testing, the microstructure type of the steel strip is "fine-grained polygonal ferrite +...

Embodiment 4

[0044] "Fine-grained polygonal ferrite + acicular ferrite" dual-phase structure steel strip, its composition raw materials are calculated by mass percentage: C: 0.065wt%, Si: 0.3 wt%, Mn: 1.9wt%, Nb: 0.07 wt%, Mo: 0.26 wt%, P: 0.01 wt%, S: 0.0020 wt%, and the balance is Fe and unavoidable impurities, which are smelted in a converter and continuously cast into a 300mm billet.

[0045] The casting billet is heated at 1200°C, the heat preservation period is more than 2 hours, the starting rolling temperature is 1100°C, the rough rolling and finishing rolling temperature is 980°C, the deformation at this temperature is 30%, the thickness of the intermediate billet is 60mm, the finishing rolling is carried out at 950°C, and the finishing rolling temperature is 790 ℃, the thickness of the finish-rolled exit steel plate is 15.3 mm; after air cooling to 750 ℃, it starts to cool at a cooling rate of 15 ℃ / S to 500 ℃ for coiling.

[0046] After testing, the microstructure type of the ste...

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Abstract

The invention discloses a polygonal ferrite-acicular ferrite two-phase steel plate / belt and a production method thereof and belongs to the technical field of high-strength low-alloy steel. The low-alloy steel comprises the following chemical components in percentage by weight: 0.03%-0.12wt% of C, 0.10wt%-1.5wt% of Si, 0.5wt%-2.1wt% of Mn, not more than 0.02wt% of P, not more than 0.01wt% of S, 0.02wt%-0.1wt% of Nb, 0.05wt%-0.45wt% of Mo, the balance being Fe and inevitable impurities. A few alloy elements including 0-0.4wt% of Cu, 0-0.5wt% of Ni, 0-0.5wt% of Cr and the like are added in the low-alloy steel. The production process comprises the following steps of: steel-making, continuous-casting, re-heating, rough-rolling, finish-rolling, cooling, relaxing and preserving the heat and quickly cooling. The polygonal ferrite-acicular ferrite two-phase steel plate / belt has the advantages of high toughness and plasticity in addition to high strength level, and is applicable to the vehicle plate filed and the pipeline steel filed with high requirements on strength, plasticity and toughness.

Description

technical field [0001] The invention belongs to the technical field of high-strength low-alloy steel, and specifically relates to a polygonal ferrite + acicular ferrite dual-phase steel plate / strip and a production method. The steel plate / strip has a dual-phase structure and fine grains. technical background [0002] Dual-phase steel in the field of low-alloy steel usually refers to ferritic-martensitic dual-phase steel or ferritic-bainite dual-phase steel, which can be obtained from low-carbon steel or low-alloy steel through critical zone treatment or controlled rolling. Due to the good combination of high strength and high ductility, this type of steel has become a new type of steel with high strength and good plasticity, and has been successfully used in the automobile manufacturing industry and pipeline transportation industry. [0003] However, the use of ferritic-martensitic dual-phase steel in welded structural parts is limited due to poor welding performance; Howev...

Claims

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Application Information

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IPC IPC(8): C22C38/12B21B37/74
Inventor 刘清友贾书君汪兵陈红桔
Owner CENT IRON & STEEL RES INST
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