Hot press-formed article and method for its manufacture

A technology of hot stamping forming and manufacturing method, which is applied in the direction of manufacturing tools, hot-dip coating process, transportation and packaging, etc. It can solve the problems of insufficient judgment standards, achieve excellent corrosion resistance after spraying, not easy to damage the mold, and combine excellent effect

Active Publication Date: 2006-07-26
NIPPON STEEL CORP +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0016] However, the standards required for corrosion resistance after spraying are increasing year by year, and the above criteria for judging become insufficient depending on the type of parts.

Method used

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  • Hot press-formed article and method for its manufacture
  • Hot press-formed article and method for its manufacture

Examples

Experimental program
Comparison scheme
Effect test

no. 1 approach

[0032] In the hot stamped product according to the first embodiment of the present invention, an iron-zinc solid solution phase exists on the surface of the steel sheet. In addition, substantially the entire plating layer may be composed of this solid solution phase.

[0033] In the present invention, the so-called iron-zinc solid solution phase has the same lattice structure as the base material α-Fe, but the lattice constant is relatively large, and it is considered to be a phase in which iron is mixed with zinc. The presence of this phase can be confirmed by using an X-ray diffractometer in combination with an elemental analysis device such as an X-ray microprobe (referred to as EPMA or XMA).

[0034] When the galvanized steel sheet is heated, zinc in the plating layer and iron in the base steel sheet diffuse into each other, and an iron-zinc intermetallic compound phase is first formed in the plating layer. When the aforementioned interdiffusion proceeds by increasing the...

no. 2 approach

[0068] The hot stamped product of the second embodiment of the present invention, such as figure 1 As shown in the schematic diagram of , there is an iron-zinc solid solution layer (hereinafter, simply referred to as a solid solution layer) that is essentially formed by an iron-zinc solid solution phase shown in 2 near the surface layer, and zinc oxide 3 forming the surface layer is formed on its upper part. the existing surface structure. That is, on the steel 1 as the base material, the iron-zinc solid solution layer 2 and the zinc oxide layer 3 thereon are sequentially formed. like figure 2 As shown, there is no surface structure in which there is a layer 4 containing a substantial amount of iron-zinc intermetallic compound between the iron-zinc solid solution layer 2 and the zinc oxide layer 3 as is generally seen. The iron-zinc solid solution layer 2 and the zinc oxide layer 3 are formed by heating the galvanized steel sheet in an oxidizing atmosphere.

[0069] In the...

Embodiment 1

[0111] This example illustrates the first embodiment of the present invention.

[0112] As a galvanized steel sheet for hot stamping, an alloyed hot-dip galvanized steel sheet is used. The characteristics are as follows, and the sheet thickness is 2mm containing C: 0.2%, Si: 0.3%, Mn: 1.3%, and P: 0.01%. The cold-rolled steel plate is used as the base steel plate, and the coating weight is 45-75g / m on one side 2 And the iron content in the coating film is 13-15%. However, in Example No. 5 of Table 1, an unplated cold-rolled steel sheet was used as a comparative example.

[0113] The thus-prepared galvanized steel sheet is heated in an atmospheric furnace at a furnace temperature of 850-950° C. for 3-10 minutes. By changing the heating conditions (combination of temperature x time), test materials for hot stamping were produced in which the thickness of the zinc oxide layer, the thickness of the iron-zinc solid solution phase, and the amount of zinc in the solid solution phas...

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Abstract

The present invention provides a hot press formed product being improved in corrosion resistance and in the adhesion of a coating film, which is produced by subjecting a zinc-based metal plated steel product to a hot press forming, and has a zinc-based metal plating layer containing and, formed thereon, a zinc oxide layer, wherein the uppermost zinc oxide layer has an average thickness of 2 mum or less; and a hot press formed product being excellent in corrosion resistance, the adhesion of a coating film, the resistance to corrosion after coating, and weldability, which has a basis steel plate (1) and, formed thereon, a layer (2) consisting essentially of an iron-zinc solid solution phase and, as the uppermost layer, a zinc oxide layer (3) having an average thickness of 5 mum or less, and has substantially no iron-zinc intermetallic compound phase, wherein the iron-zinc solid solution layer (2) and the zinc oxide layer (3) contain Al in a total amount of 0.5 g/m<2> or less and/or contain Al oxides in a total amount of 5 mg/m<2> or less in terms of Al.

Description

technical field [0001] The present invention relates to a hot stamped steel product having high strength and excellent post-spray corrosion resistance and spray-coat adhesion, and a method for producing the same. The hot stamped product and its manufacturing method of the present invention are particularly suitable for the manufacture of parts requiring high strength and corrosion resistance, so-called chassis parts and reinforcement members of automobiles. Background technique [0002] In recent years, for the purpose of reducing the weight of automobiles in order to improve the fuel efficiency of automobiles, efforts have been made to increase the strength of steel sheets and reduce the weight of steel sheets used. However, if the strength of the steel sheet becomes high, scratches and steel fractures will occur when making automobile parts by hot stamping, and the shape of the formed product will be unstable due to the springback phenomenon. [0003] As a technique for m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C2/06C23C2/26B21D22/02B24C1/00B21D53/88B24C11/00C23C2/28C23C2/34
Inventor 吉川幸宏今井和仁福井国博土岐保须藤俊太郎尾林彰市川正信
Owner NIPPON STEEL CORP
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