Heat-treated steel product having high strength and excellent chemical conversion processability, and manufacturing method for same

A technology for chemical conversion treatment and heat treatment of steel, used in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problems of poor adhesion between steel and coating film, reduced corrosion resistance, etc. Excellent effect

Active Publication Date: 2017-05-10
NIPPON STEEL CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] However, in this method, since the steel material is heated to the austenite region and rapidly cooled with a cooling medium, the strength of the steel material due to the martensitic transformation is sought, so there is also the possibility of generating scale on the surface. In the case of coating in the next process, the adhesion between the steel material and the coating film is poor, which leads to the problem that the corrosion resistance is lowered.

Method used

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  • Heat-treated steel product having high strength and excellent chemical conversion processability, and manufacturing method for same
  • Heat-treated steel product having high strength and excellent chemical conversion processability, and manufacturing method for same

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Embodiment

[0047] In order to confirm the effect of the present invention, an electric-welded steel pipe (40 mm×40 mm×1.6 mm in thickness) having a rectangular cross-section having the chemical composition shown in Table 1 was prepared as a raw material.

[0048] Table 1 (% by mass, balance: Fe and unavoidable impurities)

[0049] C Si mn P S sol.Al N Cr Ti Nb B 0.22 0.20 0.75 0.014 0.003 0.04 0.004 0.30 0.030 0.025 0.015

[0050] The raw material of the steel pipe is used figure 1 The shown hot three-dimensional bending processing device is heat-treated under the conditions shown in Table 2 to produce heat-treated steel products. In addition, about No. 3 of Table 2, tempering was implemented by the control of the cooling process of a hot-state three-dimensional bending processing apparatus.

[0051] For the obtained heat-treated steel product, after corroding the cross-sectional structure with a nital etching solution, four fields of view were...

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PUM

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Abstract

A heat-treated steel product having high strength and excellent chemical conversion processability, characterized in that the steel product has been heated to 600 degrees or above and bent, and has scales with a film thickness of at most 1 mium on the surface, wherein the scales contain FeO at a proportion of at least 90%.

Description

technical field [0001] The present invention relates to a heat-treated steel product that does not undergo a special scale removal process even after heat treatment, has excellent chemical conversion treatability as a coating base treatment, and is excellent in corrosion resistance after coating, and a production method thereof. Background technique [0002] In recent years, structural components for automobiles have been required to be thinner and stronger from the viewpoint of global environmental issues and crash safety performance. In response to these demands, there has been an increase in the number of structural parts for automobiles that use high-strength steel sheets as raw materials. However, if structural parts for automobiles are manufactured by press forming using high-strength steel sheets as raw materials, forming defects such as wrinkles and springback are likely to occur. Therefore, it is not easy to manufacture structural parts for automobiles by press for...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/76B21D7/16C21D1/18C21D1/74C21D9/08C22C38/00C22C38/32C23C22/12
CPCB21D7/16C21D1/18C21D1/74C21D9/085C21D2211/008C21D2241/00C22C38/00C22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/26C22C38/28C22C38/32B21B1/22B21B2001/225C23C22/12
Inventor 松田英树秋冈幸司植松一夫
Owner NIPPON STEEL CORP
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