Ultralow-yield-ratio cold-rolled dual-phase steel and manufacturing method thereof

A dual-phase steel, ultra-low-yield technology, applied in the field of steel materials, can solve the problems of affecting the formability, the high price of Mo element, and the impact on the final performance, to improve the formability and resilience performance, and good comprehensive mechanical properties. , to avoid the effect of wrinkling the surface of the parts

Inactive Publication Date: 2016-03-23
CENT IRON & STEEL RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the Mo element is expensive and the production cost is high. Among them, the Si-Mn-Cr system is the most widely used, but the addition of Cr alloy elements makes the process window narrow, which increases the difficulty of process control in the production process, and requires equipment capacity and control level. Higher, the fluctuation of the process has a greater impact on the final performance, which is not good for stamping and not conducive to industrial production
The hardenability of Si-Mn system is poor, and the cooling rate in the rapid cooling section of continuous annealing is not enough, so a small amount of bainite is easy to exist, which affects the formability

Method used

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  • Ultralow-yield-ratio cold-rolled dual-phase steel and manufacturing method thereof
  • Ultralow-yield-ratio cold-rolled dual-phase steel and manufacturing method thereof
  • Ultralow-yield-ratio cold-rolled dual-phase steel and manufacturing method thereof

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Effect test

Embodiment 1

[0031] The trial-manufactured DP780 cold-rolled dual-phase steel has introduced a small amount of retained austenite into the microstructure with ferrite matrix and martensite islands as the basic characteristics, thus ensuring that the strength level reaches the level of similar steel companies. , elongation A 50 Stable increase to more than 20% (A 80 ≥18%), ultra-low yield ratio 0.44~0.45. Its manufacturing process is as follows:

[0032] 1) Smelting and continuous casting into slabs, components and weight percentages of slabs: C: 0.16%, Mn: 1.81%, Si: 0.47%, Al: 0.058%, P: 0.0069%, S: 0.0038%, Nb0 .04%, the balance is Fe and unavoidable impurities;

[0033] 2) Hot rolling is performed on the slab after conventional heating, the cumulative rolling reduction is 86%, the thickness of the hot-rolled finished product is 5.0mm, and the final rolling temperature is controlled at 850-880°C;

[0034] 3) Carry out coiling, control coiling temperature at 670 ℃;

[0035] 4) Carry ou...

Embodiment 2

[0044] 1) Smelting and continuous casting into slabs, components and weight percentages of slabs: C: 0.13%, Mn: 1.7%, Si: 0.43%, Al: 0.04%, P: 0.0068%, S: 0.0079%, N : 0.0043%, Nb0.028%, the balance is Fe and unavoidable impurities;

[0045] 2) Hot rolling is performed on the slab after conventional heating, the cumulative rolling reduction is 90%, the thickness of the hot-rolled finished product is 4.5mm, and the final rolling temperature is controlled at 850-880°C;

[0046] 3) Carry out coiling, control coiling temperature at 670 ℃;

[0047] 4) Carry out conventional pickling;

[0048] 5) Carry out cold rolling, control the cumulative reduction rate of cold rolling to 66.7%, and roll into a steel plate with a thickness of 1.5mm;

[0049] 6) Carry out continuous annealing, control the annealing temperature at 800-840°C, and annealing time 90-120 seconds;

[0050] 7) Cooling to 700-740°C at a slow cooling rate of 3-5°C / s;

[0051] 8) Perform rapid cooling, the cooling spee...

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Abstract

The invention belongs to the technical field of steel materials, and relates to an ultralow-yield-ratio cold-rolled dual-phase steel and a manufacturing method thereof. Internal control chemical components of the dual-phase steel comprise 0.13%-0.18% of C, 0.30%-0.60% of Si, 1.7%-2.0% of Mn, 0.02%-0.070% of Al, 0.02%-0.05% of Nb and the balance Fe and other inevitable impurities. Simple chemical component design is adopted, the hot-rolling deformation heat treatment TMCP and the flexible continuous annealing process are combined to obtain a microscopic structure with fine grain ferrite, island martensite and 5%-7% of retained austenite, and therefore the uniform deformation capacity of materials is increased while the strong plasticity of the cold-rolled dual-phase steel is improved. The ultralow-yield-ratio cold-rolled dual-phase steel has the beneficial effects that good stamping performance, low process sensitivity and the ultralow yield ratio YS / TS which is smaller than or equal to 0.51 are achieved, springback generated after stamping can be reduced, and later deep machining of the automobile industry is facilitated.

Description

technical field [0001] The invention belongs to the technical field of iron and steel materials, and in particular provides an ultra-low yield ratio cold-rolled dual-phase steel DP780 and a manufacturing method thereof. While rolling dual-phase steel has strong plasticity, it can obtain ultra-low yield ratio, which is beneficial to the subsequent deep processing of the automobile industry. Background technique [0002] In recent years, with the increasing global energy and environmental crisis, energy conservation and emission reduction has become an important issue faced by contemporary automobile design and manufacturing. At the same time, with the continuous development of lightweight automobile bodies and the continuous improvement of passenger safety requirements, ultra-high-strength steels of 800 MPa and above have been more and more used in structural parts and reinforcements of mid-to-high-end cars to achieve energy saving and emission reduction. Improve vehicle col...

Claims

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Application Information

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IPC IPC(8): C22C38/12C21D8/02
Inventor 王卫卫李光瀛张江玲胡霄雨白宇肖金福
Owner CENT IRON & STEEL RES INST
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