High-strength galvanized steel sheet, high-strength parts and their manufacturing method

A technology of galvanized steel sheet and manufacturing method, which is applied in the direction of manufacturing tools, hot-dip coating process, furnace, etc., can solve the problems of easy formation of micropores and deterioration of bendability, etc., and achieve the improvement of collision safety, plating and bendability excellent effect

Active Publication Date: 2022-05-03
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In particular, in the case of a steel plate composed of two or more types of steel structure with different hardness, deformation concentrates at the interface of the steel structure, and micropore defects are likely to be formed, resulting in poor bendability.

Method used

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  • High-strength galvanized steel sheet, high-strength parts and their manufacturing method
  • High-strength galvanized steel sheet, high-strength parts and their manufacturing method
  • High-strength galvanized steel sheet, high-strength parts and their manufacturing method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0146] In order to confirm the influence of the amount of hydrogen in steel, the study shown in Example 1 was carried out.

[0147] Molten steel with the composition shown in Table 1 was smelted in a converter to produce slabs with an average flow rate of molten steel at the solidification interface near the meniscus of the mold at 18 cm / sec and an average casting speed of 1.8 m / min. This slab was heated to 1200°C, and a hot-rolled coil was produced at a finishing temperature of 840°C and a coiling temperature of 550°C. The hot-rolled steel sheets obtained from the hot-rolled coils were pickled, and then cold-rolled steel sheets with a thickness of 1.4 mm were produced at a cold reduction ratio of 50%. The cold-rolled steel sheet was annealed in an annealing furnace atmosphere with various hydrogen concentrations and a dew point of -30°C, and heated to an annealing temperature of 790°C (within the range of Ac3 point + 20°C or lower), so as to increase the temperature from the ...

Embodiment 2

[0156] In Example 2, the following galvanized steel sheets were manufactured and evaluated.

[0157] Melt molten steel with the composition shown in Table 2 using a converter, reheat the slab cast under the conditions shown in Table 3 to 1200°C, and perform hot rolling at a finish rolling temperature of 800 to 830°C to make the coil The temperature at the time of coiling was 560 degreeC, and the hot rolled coil was manufactured. The hot-rolled steel sheet obtained from the hot-rolled coil was pickled, and the steel sheet was subjected to the processes of cold rolling, annealing, coating treatment, width trimming, and post-treatment under the conditions shown in Table 3 to produce a 1.4 mm thick galvanized steel sheet. steel plate. It should be noted that immediately after the plating treatment (galvanizing treatment), the alloying treatment of galvanizing was performed under the conditions of 500° C. for 20 seconds. In addition, the steps of width trimming and post-processin...

Embodiment 3

[0185] The galvanized steel sheet of the production condition No. 1 (example of the present invention) in Table 3 of Example 2 was press-formed to manufacture the parts of the example of the present invention. In addition, the galvanized steel sheet of the manufacturing condition No.1 (example of the present invention) in Table 3 of Example 2 and the galvanized steel sheet of the manufacturing condition No. 2 (example of the present invention) of Table 3 of Example 2 were carried out by spot welding Joining, the parts of the example of this invention were manufactured. It was confirmed that the components of these examples of the present invention are excellent in bendability and plating property, and thus can be applied to automobile parts and the like.

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Abstract

An object of the present invention is to provide a high-strength galvanized steel sheet excellent in platability and bendability, a high-strength member, and a method for producing them. The high-strength galvanized steel sheet of the present invention comprises a steel sheet and a galvanized layer on the surface of the above-mentioned steel sheet, the above-mentioned steel sheet has the following composition and steel structure, the composition contains predetermined composition elements, the mass of the Si content and the Mn content in the steel The ratio (Si / Mn) is 0.1 or more and less than 0.2, and the rest is composed of Fe and unavoidable impurities. In this steel structure, Al, Si, and Mg exist in the range from the surface to the 1 / 3 of the plate thickness. The average particle size of inclusions of at least one type of Ca and Ca is 50 μm or less, the average closest distance of the above-mentioned inclusions is 20 μm or more, and the coating weight per one side of the above-mentioned zinc-coated layer is 20 g / m 2 ~120g / m 2 , the amount of diffusible hydrogen contained in the steel is less than 0.25 mass ppm, and the tensile strength is more than 1100 MPa.

Description

technical field [0001] The present invention relates to a high-strength galvanized steel sheet excellent in platability and bendability, suitable for building materials and crash-resistant parts of automobiles, high-strength parts, and methods for producing them. Background technique [0002] Recently, there is an increasing demand for improved crash safety and fuel efficiency of automobiles, and steel sheets used as parts materials have been increasing in strength. In addition, automobiles are widely used around the world and are used for various purposes in various regions and climates. For this reason, high rust resistance is required for steel sheets used as component materials. [0003] In general, if the strength of a steel sheet increases, its workability decreases. In particular, the plated steel sheet tends to be inferior in workability compared to the unplated steel sheet. [0004] Furthermore, it is known that it is difficult to form a high-quality plated film o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00C21D9/46C22C38/06C22C38/60C23C2/06C23C2/40C22C18/00C22C18/04
CPCC22C38/00C22C18/04C23C2/06C22C18/00C21D9/46C22C38/06C23C2/40C22C38/60C21D8/0226C21D8/0236C21D8/0263C21D8/0426C21D8/0436C21D8/0463C22C38/02C22C38/04C22C38/08C22C38/12C22C38/14C22C38/18C22C38/22C22C38/24C22C38/26C22C38/28C22C38/32C22C38/40C21D2211/005C21D2211/008C21D8/02C21D1/26C21D1/76C23C2/26C22C38/001C21D8/0247C21D8/0205C21D2211/001C21D2211/002C22C38/002C22C38/42C22C38/44C22C38/46C22C38/50C22C38/54
Inventor 吉富裕美木庭正贵中垣内达也铃木善继
Owner JFE STEEL CORP
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