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Method for Manufacturing Hot-Pressed Member

a manufacturing method and hot pressing technology, applied in the field of manufacturing hot pressing members, can solve the problems of mold damage, increase in the number of cases, deterioration of press workability, etc., and achieve the effects of increasing cost, reducing production costs, and ensuring stability

Inactive Publication Date: 2018-08-02
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present patent discloses a method to make a hot-pressed member that has a uniform surface appearance without significantly increasing cost. This method can be used to make various parts of an automobile, like the chassis and body structure.

Problems solved by technology

However, an increase in the strength of steel sheets causes a deterioration in press workability, and therefore there is an increase in the number of cases where it is difficult to form a steel sheet into desired shapes of the members.
However, the case of this hot pressing, since a steel sheet is heated to a high temperature of about 950° C. before hot pressing is performed, scale (iron oxide) is generated on the surface of the steel sheet, and the flaking of the scale occurs when hot pressing is performed, which results in a problem in that a mold is damaged or the surface of a member is damaged after the hot pressing.
Also, scale which remained on the surface of a member causes a deterioration in surface appearance and paint adhesiveness.
However, such a treatment makes a manufacturing process complex, and thus there is a decrease in productivity.
However, since a hot-pressed member, which is manufactured by using the process described above, is not provided with an anti-corrosion film such as a coating layer, the member is very poor in terms of corrosion resistance.

Method used

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  • Method for Manufacturing Hot-Pressed Member

Examples

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examples

[0067]A cold-rolled steel sheet having a chemical composition containing, by mass %, C: 0.23%, Si: 0.25%, Mn: 1.2%, P: 0.01%, S: 0.01%, Al: 0.03%, N: 0.005%, Cr: 0.2%, Ti: 0.02%, B: 0.0022%, Sb: 0.008%, and the balance being Fe and inevitable impurities, an Ac3 transformation temperature of 820° C., and a thickness of 1.6 mm was used as a base steel sheet. The surface of this cold-rolled steel sheet was coated with one of a galvanizing layer, a hot-dip Zn—Al-alloy coating layer (Al content: 55 mass %), a galvannealing layer (Fe content: 10 mass %), a Zn electroplating layer, and a Zn—Ni-alloy electroplating layer (Ni content: 12 mass %) and cut into a sample having a size of 200 mm×300 mm.

[0068]The sample obtained as described above was subjected to a surface-cleaning treatment. A surface-cleaning treatment was performed by using one of A: a wiping method with waste cloth, B: a brushing method, C: a combined method of wash-oil application and brushing, D: an alkaline degreasing meth...

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Abstract

A method for manufacturing a hot-pressed member The method includes heating a zinc-based coated steel sheet to a temperature range from an Ac3 transformation temperature to 1000° C., performing hot pressing work, and performing cooling, in which a surface-cleaning treatment is performed on the zinc-based coated steel sheet before the heating step is performed.

Description

TECHNICAL FIELD[0001]The present disclosure relates to a method for manufacturing a hot-pressed member which can preferably be used for, for example, chassis and body structure members of an automobile.BACKGROUND ART[0002]To date, for example, chassis and body structure members of an automobile have usually been manufactured by performing press working on steel sheets having a specified strength. Nowadays, since there is a strong demand for the weight reduction of an automobile body from the viewpoint of global environment conservation, efforts are being made to reduce the thickness of a steel sheet which is used for an automobile body by increasing the strength of the steel sheet. However, an increase in the strength of steel sheets causes a deterioration in press workability, and therefore there is an increase in the number of cases where it is difficult to form a steel sheet into desired shapes of the members.[0003]In view of the situation described above, Patent Literature 1 pro...

Claims

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Application Information

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IPC IPC(8): C23C2/26B21D22/26C21D9/46C23C2/06C23C2/40C25D5/50C23F17/00C22C18/00
CPCC23C2/26B21D22/26C21D9/46C23C2/06C23C2/40C25D5/50C23F17/00C22C18/00B21D53/88C25D3/22C22C38/60C22C38/28C22C38/06C22C38/04C22C38/02C22C38/002C22C38/001B21D22/20C25D5/48C21D8/0278B21D22/208
Inventor NAKAJIMA, SEIJIANDO, SATORU
Owner JFE STEEL CORP