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:
Jul. 23, 2013
Filed:
May. 01, 2012
Yoshihiro Daitoh, Fukuoka, JP;
Akira Kito, Fukuoka, JP;
Takayuki Nakamura, Fukuoka, JP;
Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;
Abstract
A hot-rolled steel bar or wire rod consisting of C: 0.1 to 0.3%, Si: 0.05 to 1.5%, Mn: 0.4 to 2.0%, S: 0.003 to 0.05%, Cr: 0.5 to 3.0%, Al: 0.02 to 0.05%, and N: 0.010 to 0.025%, the balance being Fe and impurities, and the impurities containing P: 0.025% or less, Ti: 0.003% or less, and O: 0.002% or less, wherein the structure thereof is composed of a ferrite-pearlite structure, ferrite-pearlite-bainite structure, or ferrite-bainite structure; the standard deviation of ferrite fractions at the time when randomly selected 15 viewing fields of a transverse cross section are observed and measured with the area per one viewing field being 62,500 μmis 0.10 or less; and in a region from the surface to one-fifth of the radius and a region from the center to one-fifth of the radius in the transverse cross section, the amount of Al precipitating as AlN is 0.005% or less, and the density in terms of the number of AlN having a diameter of 100 nm or larger is 5/100 μmor less. In the hot-rolled steel bar or wire rod, even if hot forging is performed in various temperature ranges, austenite grains can be stably prevented from being coarsened at the time of heating for carburization.