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A kind of 700mpa hot-rolled trip-assisted dual-phase steel and its preparation method

A dual-phase steel and main body technology, which is applied in the field of hot-rolled advanced high-strength steel for automobiles, can solve problems such as difficult to meet and difficult to form, and achieve the effects of improving safety factor, good economic applicability and application prospect

Active Publication Date: 2021-01-15
SHOUGANG CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the actual production process, we found that the traditional dual-phase steel is difficult to form on many high-drawability parts, and it is difficult to meet the requirements of complex stamping structural parts in automotive design

Method used

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  • A kind of 700mpa hot-rolled trip-assisted dual-phase steel and its preparation method
  • A kind of 700mpa hot-rolled trip-assisted dual-phase steel and its preparation method
  • A kind of 700mpa hot-rolled trip-assisted dual-phase steel and its preparation method

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0026] The second aspect of the present invention provides a method for preparing the above-mentioned 700MPa hot-rolled TRIP-assisted dual-phase steel, the steps comprising:

[0027] S1. Hot metal smelting and casting to obtain a billet meeting the chemical composition requirements, heating the billet to 1150-1250°C under the protection of 99.99% high-purity nitrogen and keeping it warm for 1.5-2.5 hours;

[0028] S2. Controlled hot rolling of the slab after heat preservation, the controlled hot rolling includes 2-3 passes of rough rolling and 3-5 passes of finish rolling, the total reduction of the rough rolling is 82-84%, and the rough rolling After each pass, it enters the coil box for heat preservation treatment. The finish rolling is rolled at a constant speed of 7-8m / s, and the total reduction of finish rolling is 84-85%. steel belt;

[0029] S3. Water-cool the hot-rolled steel strip to 680-700°C at a cooling rate of 60-70°C / s, then air-cool for 20-30s, and then water-c...

Embodiment 1

[0032] This embodiment provides a method for preparing a 700MPa hot-rolled TRIP-assisted dual-phase steel, the steps of which include:

[0033] Heat the billet to 1200°C for 2 hours, and protect it with nitrogen with a purity of 99.99%. The chemical composition of the slab is as follows: by mass percentage, C: 0.142%, Si: 0.65%, Mn: 1.68%, Al: 0.62%, P: 0.014%, S: 0.002%, the rest is Fe and not Avoid impurities.

[0034] The hot-rolled slab after heating and heat preservation is started at 1180°C. During the hot-rolling and cooling process, the structure of the hot-rolled steel strip is controlled to be a three-phase structure of ferrite, martensite and a small amount of film-like retained austenite. The controlled hot rolling process is as follows: carry out 3 passes of rough rolling, the total reduction of rough rolling is 83%, and after each pass, enter the coil box for heat preservation treatment; / s speed uniform rolling, the total reduction of finishing rolling is 85%....

Embodiment 2

[0037] Example 2, Example 3, and Example 4 all provide a method for preparing a 700MPa hot-rolled TRIP-assisted dual-phase steel. The preparation method is basically the same as that of Example 1, and the difference lies in the chemical composition of the slab and part of the preparation process. Parameters, specifically, the chemical composition of the slab used in Examples 2-4 is shown in Table 1, and the control requirements of the preparation process parameters are shown in Table 2, and the preparation process of the rest of the unmentioned parts is the same as that of Example 1. The microstructure and mechanical properties of the products obtained in Examples 2-4 are shown in Table 2.

[0038] Table 1 each embodiment billet chemical composition mass percent (%)

[0039]

[0040]

[0041] Table 2 Control requirements and mechanical properties of each embodiment (80mm gauge length)

[0042]

[0043] It can be seen from Table 2 that the TRIP-assisted dual-phase ste...

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Abstract

The invention provides 700MPa-level hot-rolled TRIP auxiliary dual-phase steel and a preparation method thereof. The tissue of the 700MPa-level hot-rolled TRIP auxiliary dual-phase steel is residual austenite, martensite and ferrite, wherein the surface-layer tissue comprises 3-6% of the residual austenite, 16-25% of martensite and the balance of ferrite; point-like carbide is provided in the ferrite; the steel main body tissue comprises 2-5% of the residual austenite, 26-40% of martensite and the balance of ferrite; and no carbide is separated out from the ferrite. The steel has specified plastic extension strength of 384-406 MPa, has tensile strength of 692-707 MPa, and has percentage elongation after fracture (80mm gauge length) of 22.5-24.5%. The steel provided by the invention can beapplied to a complex automobile structure part and a chassis part, and has relatively good economical efficiency and a relatively good application prospect.

Description

technical field [0001] The invention belongs to the technical field of advanced high-strength steel for hot-rolled automobiles, and in particular relates to a 700MPa hot-rolled TRIP-assisted dual-phase steel and a preparation method thereof. Background technique [0002] At present, hot-rolled advanced high-strength steels for automobiles such as dual-phase (DP) steels and transformation-induced plasticity (TRIP) steels have been applied to the preparation of automotive structural parts. In the actual production process, we found that the traditional dual-phase steel is difficult to form on many high-drawability parts, and it is difficult to meet the requirements of complex stamping structural parts for automotive design. However, when phase transformation induced plasticity steel is used, there is a certain margin in the elongation rate, which causes waste, and the higher the strength level, the worse the weldability, but the residual austenite in TRIP steel can absorb ener...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C21D8/02
CPCC21D8/0226C21D2211/001C21D2211/004C21D2211/005C21D2211/008C22C38/02C22C38/04C22C38/06
Inventor 刘杰郭佳刘锟代晓莉李文远陈斌郭子峰张旭
Owner SHOUGANG CORPORATION
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