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:
Apr. 24, 2012
Filed:
Mar. 12, 2007
Tetsuo Soshiroda, Kakogawa, JP;
Tetsuji Hoshika, Kakogawa, JP;
Tetsuo Soshiroda, Kakogawa, JP;
Tetsuji Hoshika, Kakogawa, JP;
Kobe Steel, Ltd., Kobe-shi, JP;
Abstract
The present invention provides a high-strength steel material capable of suppressing formation of blowholes during welding even if the strength thereof is improved by nitriding, and a method of manufacturing such a high-strength steel material by using a low rolling force. A high-strength steel of the present invention contains 0.05% (percent by mass unless otherwise specified in describing chemical composition) or below C, 1% or below Si, 1.5% or below Mn, 0.05% or below P, 0.05% or below S, 0.05% or below Al, 0.02 to 0.3% Ti, and 0.020% or below N. The high-strength steel material has metallographic structure of a single phase of ferrite and contains Ti nitride grains having a maximum size of 20 nm or below and coherently precipitated in a density of 250 grains/μmor above. In the high-strength steel material, the ratio of the number of Ti nitride grains having a maximum size of 6 nm or below to that of Ti nitride grains having a maximum size of 20 nm or below is 80% or above.