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.

Date of Patent:
Jul. 13, 2021

Filed:

Dec. 04, 2015
Applicant:

Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;

Inventors:

Keiichi Kondo, Izumisano, JP;

Yuji Arai, Amagasaki, JP;

Takanori Sato, Kitaibaragi, JP;

Assignee:
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C21D 9/08 (2006.01); C21D 8/10 (2006.01); C22C 38/00 (2006.01); C22C 38/54 (2006.01); C21D 6/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01);
U.S. Cl.
CPC ...
C21D 9/08 (2013.01); C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/10 (2013.01); C21D 8/105 (2013.01); C22C 38/00 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/42 (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 2211/001 (2013.01); C21D 2211/008 (2013.01);
Abstract

A low-alloy steel has a composition including, by mass %, C: more than 0.45 and up to 0.65%; Si: 0.05 to 0.50%; Mn: 0.10 to 1.00%; P: up to 0.020%; S: up to 0.0020%; Cu: up to 0.1%; Cr: 0.40 to 1.50%; Ni: up to 0.1%; Mo: 0.50 to 2.50%; Ti: up to 0.01%; V: 0.05 to 0.25%; Nb: 0.005 to 0.20%; Al: 0.010 to 0.100%; B: up to 0.0005%; Ca: 0 to 0.003%; 0: up to 0.01%; N: up to 0.007%; and other elements. A microstructure consists of tempered martensite and retained austenite <2% in volume fraction, crystal grain size number being 9.0 or larger, number density of carbonitride-based inclusions with grain diameter of 50 μm or larger being 10 inclusions/100 mmor smaller, and yield strength being 965 MPa or higher.


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