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:
Feb. 05, 2008
Filed:
Nov. 22, 2006
Kouji Nakaike, Wakayama, JP;
Tetsuya Nakanishi, Wakayama, JP;
Junji Nakata, Wakayama, JP;
Sumitomo Metal Industries, Ltd., Osaka, JP;
Abstract
A round billet containing, by mass %, 10.50 to 14.00% of Cr with a value represented by the equation of 'Cr+4Si−(22C+0.5Mn+1.5Ni+30N)' of not more than 9.0%, wherein the symbols of the elements represent the contents, by mass %, of the elements in the steel, is heated at a soaking temperature of 1100 to 1250 ° C. so that an in-furnace time (min) is not less than '0.5×Diameter of the round billet (mm)', and then pierced and rolled with a piercing efficiency by a piercing mill of not less than 50%, a value regulated by the equation: “{(Diameter of the round billet−Roll gap at the foremost end of the plug)/Diameter of the round billet}×100” of not more than 8.0, and a plug shape represented by the equation: “Radius of foremost end of the plug (mm)/Diameter of the round billet (mm)” of 0.06 to 0.17. The thus-manufactured high-Cr seamless steel pipe or tube has excellent internal surface properties with minimized internal surface defects.