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Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof

a technology of stainless steel and corrosion resistance, applied in the field of stainless steel pipes, can solve the problems of rusting, corrosion resistance is likely to deteriorate, and the stability (reliability) of stainless steel weather resistance is eliminated, and achieves excellent corrosion resistance and not rust.

Inactive Publication Date: 2018-10-25
NISSHIN STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides a stainless steel pipe that can resist corrosion in sea environments, preventing it from rusting quickly. The method of manufacturing this pipe is also provided.

Problems solved by technology

Conventionally, stainless steel exhibits excellent weather resistance as a material, but there is a case in which the inherent weather resistance of the material is not exerted and remarkable rusting occurs depending on the state of polishing finish, and this is one of the factors to eliminate the stability (reliability) of the weather resistance of stainless steel.
For example, there is a case in which rusting occurs in a short period of about one month after stainless steel is constructed into outdoor handrails and the like.
Hence, rusting proceeds from the oxide film and the Cr-depleted layer right under the oxide film and corrosion resistance is likely to deteriorate when the oxide film remains.
In addition, with regard to the polishing marks which are scratches engraved on the surface of the stainless steel pipe by polishing as well, the possibility that it is difficult to remove the oxide film formed by polishing using a flap wheel or the like by buffing and the oxide film remains is higher as the concave portion of the polishing marks is deeper, and rusting proceeds and corrosion resistance is likely to deteriorate since the concave portion of the polishing marks becomes a starting point of rusting.

Method used

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  • Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof
  • Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof
  • Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0059]Polishing of Steel Type 1 was conducted in Line 1 (applied with a solid polishing agent).

example 2

[0060]Polishing of Steel Type 1 was conducted in Line 3 (not applied with a solid polishing agent) and then in Line 4 (applied with a solid polishing agent). Thereafter, polishing to uniformly adjust the random polishing marks was manually conducted by the movement formed by combining an eccentric motion and a rotational motion using a polishing apparatus (air sander) to which a nonwoven fabric (#80) was attached without applying a solid polishing agent.

reference example 1

[0063]Polishing of Steel Type 2 was conducted in Line 1 (applied with a solid polishing agent).

(Surface Defects)

[0064]The polished surface of a stainless steel pipe was enlarged by 200-fold and observed in a range of 100 μm×100 μm (0.01 mm2) using an optical microscope. The surface was evaluated as “◯” to be in a state in which the generation of surface defects was suppressed in a case in which the number of surface defects having covering by the metal base of 5 μm or more was 5 or fewer, and the surface was evaluated as “x” to be in a state in which the generation of surface defects was suppressed in a case in which the number of surface defects was more than 5 (see Table 1).

[0065]As presented in Table 1, the surface of the stainless steel pipe of Example 1 did not have surface defects as illustrated in FIG. 1A. Meanwhile, the surface of the stainless steel pipe of Comparative Example 1 had at least nine surface defects as illustrated in FIG. 1B, and thus it was not in a state in w...

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Abstract

A stainless steel pipe may be provided which exhibits excellent corrosion resistance so as not to rust at an early stage even in a waterfront environment affected by sea salt particles. The stainless steel pipe may have a polishing mark on a surface, an oxide film exhibiting color is not present on the surface, and an average number of surface defects including covering by a metal base of 5 μm or more on the surface is suppressed to 5 or fewer per 0.01 mm2.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is the U.S. national stage of application No. PCT / JP2016 / 076142, filed on Sep. 6, 2016. Priority under 35 U.S.C. § 119(a) and 35 U.S.C. § 365(b) is claimed from Japanese Application No. 2015-197977, filed on Oct. 5, 2015, the disclosure of which is also incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to a stainless steel pipe exhibiting excellent corrosion resistance and a method of manufacturing the same.BACKGROUND ART[0003]Stainless steel is widely used in building material applications such as roofing materials, wall materials, and building components since it exhibits excellent weather resistance, processability, weldability, and the like. In addition, a stainless steel pipe is used in applications such as handrails, fences, and pipe shutters after being subjected to surface polishing since it exhibits excellent designing property as well.[0004]In the general industrial polishing of this stainl...

Claims

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Application Information

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IPC IPC(8): B24B29/08
CPCB24B29/08C22C38/00C22C38/58
Inventor SAIDA, TOMOAKITAI, YOSHIKAZUIMAKAWA, KAZUNARI
Owner NISSHIN STEEL CO LTD