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:
Sep. 02, 2025

Filed:

Nov. 02, 2020
Applicant:

Nippon Steel Corporation, Tokyo, JP;

Inventors:

Manabu Kubota, Tokyo, JP;

Taketo Maejima, Tokyo, JP;

Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B21K 1/08 (2006.01); C21D 9/30 (2006.01); C22C 38/00 (2006.01);
U.S. Cl.
CPC ...
B21K 1/08 (2013.01); C21D 9/30 (2013.01); C22C 38/00 (2013.01);
Abstract

A crankshaft with improved fatigue strength and machinability is provided. The crankshaft includes a pin and journal, having a chemical composition of, in mass %: 0.40 to 0.60% C; 0.01 to 1.50% Si; 0.4 to 2.0% Mn; 0.01 to 0.50% Cr; 0.20 to 0.50% Al; 0.001 to 0.02% N; up to 0.03% P; 0.005 to 0.20% S; 0.005 to 0.060% Nb; 0 to 0.060% Ti; and balance Fe and impurities, wherein, for each of the pin and journal, the hardness measured at a position at a depth of ¼ of the diameter from the surface is higher than HV 245, the microstructure at that position is mainly composed of ferrite/pearlite, and the fraction of ferrite is not lower than 16%.


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