Vanadium-microalloyed hot-rolled transformation induced plasticity steel and preparation method

A transformation-induced plasticity and alloying technology, applied in the field of metallurgical materials, can solve the problems that Al cannot provide solid solution strengthening, lose toughness and formability, reduce Paralympic stability, etc., achieve excellent comprehensive performance, and prevent growth. , the effect of improving the surface quality

Active Publication Date: 2014-07-02
LAIWU IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] (1) Al replaces part of Si: similar to Si, Al can inhibit or delay the precipitation of cementite, so the use of Al instead of Si can improve the surface quality, but since Al cannot provide the same solid solution strengthening effect as Si, it reduces the In addition to the tensile properties, it will also significantly increase the Ms point and reduce the stability of Paralympics;
[0006] (2) Increase the C content: increasing the C content to 0.3-0.4%, can make the strength of the phase transformation induced plasticity steel reach more than 1000MPa, but such a high C content will seriously affect the welding performance and make hot rolling difficult;
[0007] (3) Increase the content of martensite: using a small amount of martensite in the final structure can increase the strength, but it will lose toughness and formability

Method used

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  • Vanadium-microalloyed hot-rolled transformation induced plasticity steel and preparation method
  • Vanadium-microalloyed hot-rolled transformation induced plasticity steel and preparation method
  • Vanadium-microalloyed hot-rolled transformation induced plasticity steel and preparation method

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Experimental program
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Effect test

Embodiment 1

[0051] The chemical composition of the steel used in this embodiment is C: 0.18%, Si: 0.24%, Mn: 1.36%, V: 0.16%, N: 0.01%, P: 0.054%, S: 0.003%, and the balance For Fe and other unavoidable impurities.

[0052] According to the above composition requirements, it is smelted into steel ingots, heated to 1200°C, and forged into slabs with a thickness of 100mm. Put the slab into a heating furnace and heat it to 1190°C, keep it warm for 2 hours, and then adopt two-stage controlled rolling: the rolling start temperature in the recrystallization zone is 1100-1120°C, and the cumulative reduction rate is 80%, to obtain a 20mm thick intermediate slab ; The starting rolling temperature in the non-recrystallized area is 900-915°C, and the rolling temperature of the last few passes is properly reduced during the rolling process, so that the final rolling temperature is 800-840°C, and the cumulative reduction rate is 85%. Steel thickness is 3.0mm.

[0053] The hot-rolled steel strip adop...

Embodiment 2

[0065] The chemical composition of the steel used in this embodiment is C: 0.20%, Si: 0.50%, Mn: 1.0%, V: 0.18%, N: 0.0196%, P: 0.06%, S: 0.005%, and the rest The amount is Fe and other unavoidable impurities.

[0066] According to the above composition requirements, it is smelted into steel ingots, heated to 1190°C, and forged into slabs with a thickness of 150mm. Put the slab into a heating furnace and heat it to 1200°C, keep it warm for 1 hour, and then adopt two-stage controlled rolling: the rolling start temperature in the recrystallization zone is 1120-1130°C, and the cumulative reduction rate is 80%, to obtain a 30mm thick intermediate billet ; The starting rolling temperature in the non-recrystallized area is 920-935°C, and the rolling temperature of the last few passes is appropriately reduced during the rolling process, so that the final rolling temperature is 800-840°C, and the cumulative reduction rate is 86.7%. Steel thickness is 4.0mm.

[0067] The hot-rolled s...

Embodiment 3

[0075] The chemical composition of the steel used in this embodiment is C: 0.21%, Si: 0.16%, Mn: 1.5%, V: 0.19%, N: 0.0215%, P: 0.049%, S: 0.004%, and the rest The amount is Fe and other unavoidable impurities.

[0076]According to the above composition requirements, it is smelted into steel ingots, heated to 1190°C, and forged into slabs with a thickness of 150mm. Put the slab into the heating furnace and heat it to 1210°C, hold it for 2 hours, and then adopt two-stage controlled rolling: the rolling start temperature in the recrystallization zone is 1140-1150°C, and the cumulative reduction rate is 80%, to obtain a 30mm thick intermediate slab ; The starting rolling temperature in the non-recrystallized area is 940-950°C, and the rolling temperature of the last few passes is appropriately reduced during the rolling process, so that the final rolling temperature is 810-840°C, and the cumulative reduction rate is about 86.7%. The strip thickness is 4.0mm.

[0077] The hot-ro...

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Abstract

The invention discloses vanadium-microalloyed hot-rolled transformation induced plasticity steel with a grade above 1000MPa and a preparation method. The hot-rolled transformation induced plasticity steel comprises the following components by mass percent: 0.18-0.23% of C, not more than 0.50% of Si, 1.0-1.5% of Mn, 0.16-0.20% of V, 0.01-0.03% of N, not more than 0.06% of P, not more than 0.005% of S and the balance of Fe and other inevitable impurities. Through reasonable component design and process control, the tensile strength is not less than 1000MPa, the elongation at break is not less than 22.0%, the yield ratio is not more than 0.69, the work hardening index is not less than 0.22, the hole expansion rate is not less than 90%, the volume fraction of residual austenite in microscopic structures is not less than 12.0%, and fine V (C, N) precipitated particles with diameters of 2-5nm are diffusely distributed in a matrix.

Description

technical field [0001] The invention belongs to the technical field of metallurgical materials, and in particular relates to a vanadium microalloyed hot-rolled phase transformation-induced plasticity steel with a level above 1000 MPa and a preparation method thereof. Background technique [0002] With the impact of the global warming effect and the increasing carbon dioxide emissions, it has become a major trend in the development of the automotive industry to achieve vehicle lightweight while improving safety performance. The wide application of high-strength steel and advanced manufacturing technology is an effective way to solve this problem. [0003] Although transformation-induced plasticity steel has the advantages of high strength and high plasticity at the same time, it needs to add a certain amount of Si (about 1.5%) to inhibit the precipitation of cementite, so as to obtain a certain volume fraction of retained austenite at room temperature. However, the high Si co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/12C21D8/02
Inventor 侯晓英王业勤韩杰许荣昌
Owner LAIWU IRON & STEEL GRP
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