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.:
Date of Patent:
Oct. 18, 2016
Filed:
Mar. 18, 2011
Takeshi Suzuki, Yokohama, JP;
Yoshiki Ono, Yokohama, JP;
Shimpei Kurokawa, Yokohama, JP;
NHK SPRING CO., LTD., Kanagawa, JP;
Abstract
A surface treatment method for a steel material includes carbonitriding, quenching, and tempering. The steel material consists of, by weight %, 0.27 to 0.48% of C, 0.01 to 2.2% of Si, 0.30 to 1.0% of Mn, not more than 0.035% of P, not more than 0.035% of S, and the balance of Fe and inevitable impurities. The carbonitriding step is performed by heating the steel at a temperature of not less than the Apoint and not more than 1100° C. and bringing the steel into contact with a mixed gas atmosphere so as to concentrate nitrogen and carbon at a surface layer of the steel. The quenching step is performed by cooling the steel to room temperature at a rate of not less than 20° C./second. The tempering step is performed by heating the steel at a temperature of 100 to 400° C.