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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 9890445 B1

PDFFull Text
Date of Patent:
Feb. 13, 2018

Filed:

Dec. 11, 2012

Steel for mechanical structure for cold working, and method for manufacturing same

Applicant:

Kobe Steel, Ltd., Kobe-shi, JP;

Inventors:

Kouji Yamashita, Kobe, JP;

Takehiro Tsuchida, Kobe, JP;

Masamichi Chiba, Kobe, JP;

Assignee:

Kobe Steel, Ltd., Kobe-shi, JP;

Attorney:

Oblon, McClelland, Maier & Neustadt, L.L.P.

Primary Examiner:

Scott Kastler

Assistant Examiner:

Vanessa T Luk

Int. Cl.
CPC ...
C22C 38/48 (2006.01); C22C 38/50 (2006.01); C21D 1/32 (2006.01); C21D 8/02 (2006.01); C22C 38/22 (2006.01); C21D 8/06 (2006.01); C22C 38/06 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/08 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01); C22C 38/16 (2006.01); C22C 38/18 (2006.01); C21D 8/00 (2006.01);
U.S. Cl.
CPC ...
C22C 38/22 (2013.01); C21D 1/32 (2013.01); C21D 8/0226 (2013.01); C21D 8/06 (2013.01); C21D 8/065 (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 38/08 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C22C 38/18 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C21D 8/005 (2013.01); C21D 2211/005 (2013.01); C21D 2211/009 (2013.01);
Abstract

Provided are a steel for a mechanical structure for cold working, and a method for manufacturing the same, whereby softening and variations in hardness can be reduced even when a conventional spheroidizing annealing process is performed. A steel having a predetermined chemical composition, the total area ratio of pearlite and pro-eutectoid ferrite being at least 90 area % with respect to the total metallographic structure of the steel, the area ratio (A) of pro-eutectoid ferrite satisfying the relationship A>Ae with an Ae value expressed by a predetermined relational expression, the average equivalent circular diameter of bcc-Fe crystal grains being 15-35 μm, and the average of the maximum grain diameter and the second largest grain diameter of the bcc-Fe crystal grains being 50 μm or less in terms of equivalent circular diameter.

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