Hot-pressed steel sheet member, production method for same, and steel sheet for hot pressing

A technology of hot-dip galvanizing and manufacturing method, which is applied in manufacturing tools, chemical instruments and methods, hot-dip plating process, etc. Effect

Active Publication Date: 2016-08-03
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, such an ultra-high-strength steel sheet is difficult to form, and it is difficult to directly ap

Method used

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  • Hot-pressed steel sheet member, production method for same, and steel sheet for hot pressing
  • Hot-pressed steel sheet member, production method for same, and steel sheet for hot pressing
  • Hot-pressed steel sheet member, production method for same, and steel sheet for hot pressing

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Embodiment 1

[0127] Steels having the compositions shown in Table 1 were melted in a vacuum melting furnace, and billets were produced by billet rolling. It should be noted that in Table 1, N is an unavoidable impurity.

[0128]

[0129] These slabs were heated to 1200°C, rough-rolled, finish-rolled, and coiled to produce hot-rolled sheets. Next, it was cold-rolled to 1.4 mm to make a cold-rolled sheet, and the obtained cold-rolled sheet was subjected to annealing. The hot rolling conditions, cold rolling conditions and annealing conditions are shown in Tables 2 and 3. Immerse the steel plate prepared under the conditions shown in Table 2 and 3 in a coating bath at 460°C to form a coating with a coating weight of 35-45g / m 2 The hot-dip galvanized layer was then cooled at a cooling rate of 10°C / sec to obtain a hot-dip galvanized steel sheet (GI). In addition, some steel sheets were subjected to alloying treatment at 530°C after the hot-dip galvanized layer was formed, and cooled at a ...

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Abstract

Provided is a high strength hot-dip galvanized steel sheet having a tensile strength of at least 1180 MPa and excellent impact resistance and bending workability, wherein: the steel sheet satisfies a specific alloy composition; the steel sheet is obtained from 0-10% area ratio of ferrite, 15-60% area ratio of martensite, 20-50% area ratio of tempered martensite, and 20-50% area ratio of bainitic ferrite; the respective mean grain sizes of the massive martensite, tempered martensite, and bainitic ferrite are 15 Miu or less; the value obtained by subtracting the tempered martensite area ratio from the bainitic ferrite area ratio is 20% or less; in the total martensite area ratio, the area ratio of martensite for which the neighboring phase is obtained solely from martensite is 5% or less; and the value obtained by subtracting the Vickers hardness at a depth of 20 miu from the steel sheet surface from the Vickers hardness at a depth of 100 Miu from the steel sheet surface is 30 or more. Also provided is a manufacturing method therefor.

Description

technical field [0001] The present invention relates to a high-strength hot-dip galvanized steel sheet excellent in impact resistance and bending workability suitable for use as a steel sheet for automobiles, and to a method for producing the same. Background technique [0002] From the viewpoint of protecting the global environment, in order to reduce CO 2 Emissions, for the automobile industry, it is always important to reduce the weight of the car while maintaining the strength of the car body, and to improve the fuel consumption of the car. In order to reduce the weight of an automobile body while maintaining its strength, it is effective to increase the strength of the steel sheet used as a raw material for automobile parts to reduce the thickness of the steel sheet. On the other hand, many automobile parts made of steel sheets are formed by pressing, flanging, and the like. Therefore, high-strength steel sheets used as raw materials for automobile parts are required ...

Claims

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Application Information

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IPC IPC(8): C22C38/00C21D9/46C22C38/38C22C38/58C23C2/02C23C2/06C23C2/28
CPCC23C2/02C23C2/06C22C38/00C22C38/38C22C38/58B32B15/013C22C38/001C22C38/002C22C38/005C22C38/02C22C38/06C22C38/20C22C38/22C22C38/24C22C38/26C22C38/28C22C38/32C22C38/48C22C38/50C22C38/54C21D9/46C21D1/22C21D6/002C21D6/005C21D6/008C21D8/0205C21D8/0226C21D8/0236C21D8/0263C21D2211/005C21D2211/008C23C2/024C23C2/0224C23C2/29C23C2/022
Inventor 长谷川宽金子真次郎牧水洋一铃木善继
Owner JFE STEEL CORP
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