Method for improving elongation of cold-rolled dual-phase steel by utilizing retained austenite

A technology of retained austenite and dual-phase steel, applied in the field of iron and steel materials, can solve problems that have not attracted attention, and achieve good plasticity, good plasticity, and good comprehensive performance

Inactive Publication Date: 2015-08-26
CENT IRON & STEEL RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, Thyssen Steel Company proposed a new type of high-plastic dual-phase steel in 2007, and a small amount of retained austenite was observed in its microstructure, but it did not attract attention

Method used

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  • Method for improving elongation of cold-rolled dual-phase steel by utilizing retained austenite
  • Method for improving elongation of cold-rolled dual-phase steel by utilizing retained austenite
  • Method for improving elongation of cold-rolled dual-phase steel by utilizing retained austenite

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Experimental program
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Effect test

Embodiment 1

[0027] 1) Internally controlled chemical composition of cold-rolled dual-phase steel DP600: C 0.08-0.11%, Si 0.25-0.35%, Mn 1.5-1.7%, Al0.027%, P0.01%, Cr0.3-0.5%, Fe quantity.

[0028] 2) Hot rolling is carried out after the slab is conventionally heated, the rolling thickness is 2.7mm, and the final rolling temperature is controlled at 880°C;

[0029] 3) Carry out conventional coiling, and control the coiling temperature at 650°C;

[0030] 4) Carry out conventional pickling;

[0031] 5) Carry out cold rolling, and control the cumulative reduction rate of cold rolling to 63%; roll into a steel plate with a thickness of 1.0mm;

[0032] 6) In the process of continuous annealing, firstly keep isothermal at 820°C for 100s, after 20s of slow cooling time, slowly cool to 700°C, and then rapidly cool to martensite at a cooling rate of 40≤Vc≤66°C / s Below the point Ms, about 320°C, continue isothermally maintaining at this temperature for 420s; the final cooling treatment temperatu...

Embodiment 2

[0037]The DP800 grade cold-rolled dual-phase steel trial-produced in the laboratory 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. At the same time, the elongation rate A 50 Stable increase to more than 20% (A 80 ≥18%). Its manufacturing process is as follows:

[0038] 1) The internal control chemical composition of cold-rolled dual-phase steel DP800 is C 0.14-0.18%, Si 0.3-0.6%, Mn 1.75-2.0%, Al 0.04-0.06%, Nb 0.03-0.05%, and the balance Fe.

[0039] 2) Hot rolling is performed on the slab after conventional heating, rolling to 3.6mm, and the final rolling temperature is controlled at: 860°C;

[0040] 3) Carry out coiling, control coiling temperature at 670 ℃;

[0041] 4) Carry out conventional pickling;

[0042] 5) Carry out cold rolling, and control the cumulative reduction rate of cold...

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Abstract

The invention discloses a method for improving the elongation of cold-rolled dual-phase steel by utilizing retained austenite and belongs to the technical field of steel materials. By the combination of the unique chemical component design, a hot-rolled ausforming TMCP (Thermal Mechanical Control Process) and a flexible continuous annealing process, complex-phase tissues including island martensite scattered and distributed on refined ferrite serving as a matrix and 2-7 percent of the retained austenite are obtained, so that dual-phase steel tissues include the ferrite, the martensite and the retained austenite. The content of the retained austenite is controlled through a component-continuous annealing process, the hardening performance of the generated martensite is highly superior to that of the austenite before phase changing, the uniform deformability of a material is improved, and the plasticity of the material is improved accordingly. A checking result for mechanical performance shows that high strength and high plasticity are obtained at the same time, and the elongation is improved by 4-5 percent in comparison with a conventional process.

Description

technical field [0001] The invention belongs to the technical field of iron and steel materials, and in particular provides a method for improving the elongation of cold-rolled dual-phase steel by using retained austenite. A certain amount of retained austenite undergoes phase transformation to induce plasticity, thereby greatly increasing the elongation. Rate. Background technique [0002] In order to meet the increasing requirements of the automotive industry on the strength level and performance of automotive materials, the development of advanced high-strength steels with high uniform elongation, high n value, and high strength-plastic product TS×Et has become the key to lightweight vehicles. As a typical representative of the first generation of advanced high-strength steel, dual-phase steel (Dual Phase steel) has the advantages of high strength, good elongation and formability, strong absorption of collision energy and other advantages (strength-plastic product at 15GP...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/38C22C38/26C22C38/18C22C38/12C22C38/06C21D8/00
CPCY02P10/20
Inventor 王卫卫李光瀛张江玲胡霄雨白宇
Owner CENT IRON & STEEL RES INST
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