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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 10519524 B1

PDFFull Text
Date of Patent:
Dec. 31, 2019

Filed:

Feb. 25, 2016

Ferritic heat-resistant steel and method for producing the same

Applicant:

National Institute for Materials Science, Tsukuba-shi, Ibaraki, JP;

Inventors:

Kazuhiro Kimura, Tsukuba, JP;

Kota Sawada, Tsukuba, JP;

Hideaki Kushima, Tsukuba, JP;

Yasushi Taniuchi, Tsukuba, JP;

Toshio Ohba, Tsukuba, JP;

Assignee:

NATIONAL INSTITUTE FOR MATERIALS SCIENCE, Tsukuba-Shi, Ibaraki, JP;

Attorney:

Manabu Kanesaka

Primary Examiner:

Anthony J Zimmer

Assistant Examiner:

Ricardo D Morales

Int. Cl.
CPC ...
C21D 6/00 (2006.01); C21D 1/28 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/02 (2006.01); C22C 38/50 (2006.01); C22C 38/22 (2006.01); C22C 38/30 (2006.01); C22C 38/54 (2006.01); C22C 38/00 (2006.01); C22C 38/48 (2006.01); C22C 38/04 (2006.01); C22C 38/32 (2006.01); C22C 38/26 (2006.01); C22C 38/06 (2006.01); C22C 38/24 (2006.01);
U.S. Cl.
CPC ...
C21D 6/008 (2013.01); C21D 1/28 (2013.01); C21D 6/00 (2013.01); C21D 6/002 (2013.01); C21D 6/004 (2013.01); C21D 6/005 (2013.01); C22C 38/00 (2013.01); C22C 38/001 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/22 (2013.01); C22C 38/24 (2013.01); C22C 38/26 (2013.01); C22C 38/30 (2013.01); C22C 38/32 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C22C 38/54 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01);
Abstract

The invention provides a ferritic heat-resistant steel whose creep rupture ductility in a long-term region is improved without detrimental to creep strengths. The ferritic heat-resistant steel has a chemical composition comprising, in % by mass, C: 0.03 to 0.15, Si: 0 to 0.8, Mn: 0.1 to 0.8, Cr: 8.0 to 11.5, Mo: 0.2 to 1.5, (W: 0.4 to 3.0), V: 0.1 to 0.4, Nb: 0.02 to 0.12 N: 0.02 to 0.10 with the balance of iron and inevitable impurities. This steel has a tempered martensite microstructure, and has an improved creep rupture ductility even when there is a load within the elastic limits at temperatures at which the ferritic heat-resistant steel is used, because internal strain or internal stress induced by martensitic transformation is relaxed or released by an intermediate tempering heat treatment in a two-phase state temperature in which a portion of an austenitic phase undergoes martensitic transformation.

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