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The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Patent No.:

US 11512374 B1

PDFFull Text
Date of Patent:
Nov. 29, 2022

Filed:

Mar. 30, 2018

Duplex stainless steel and manufacturing method thereof

Applicant:

Nippon Steel Stainless Steel Corporation, Tokyo, JP;

Inventors:

Shinji Tsuge, Tokyo, JP;

Yuusuke Oikawa, Tokyo, JP;

Assignee:

NIPPON STEEL STAINLESS STEEL CORPORATION, Tokyo, JP;

Attorney:

Birch, Stewart, Kolasch & Birch, LLP

Primary Examiner:

Jophy S Koshy

Int. Cl.
CPC ...
C22C 38/44 (2006.01); C21D 6/00 (2006.01); C21D 6/04 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/42 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01); C22C 38/54 (2006.01); C22C 38/16 (2006.01); C22C 38/12 (2006.01); C22C 38/52 (2006.01); C22C 38/46 (2006.01);
U.S. Cl.
CPC ...
C22C 38/44 (2013.01); C21D 6/002 (2013.01); C21D 6/004 (2013.01); C21D 6/008 (2013.01); C21D 6/04 (2013.01); C21D 8/0205 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/005 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/12 (2013.01); C22C 38/16 (2013.01); C22C 38/42 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C22C 38/52 (2013.01); C22C 38/54 (2013.01); C21D 8/0226 (2013.01);
Abstract

A duplex stainless steel and method of manufacturing the same, said steel having an amount of Cr in an extraction residue [Cr] of 0.005 to 0.050% and an amount of Nb in an extraction residue [Nb] of 0.001 to 0.080%, the [Nb]/[Cr] ratio being 0.2 or more. By slow cooling down to 800° C., then fast cooling down to 600° C., it is possible to control the precipitation of chromium nitrides and niobium nitrides, and by making the ratio [Nb]/[Cr] 0.2 or more, it is possible to raise the corrosion resistance. Further, by reducing Mn to less than 2.0% and N to 0.25% or less, then adding a trace amount of Nb, the effect of raising the critical pitting temperature CPT is obtained.

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