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:
Jun. 25, 2019
Filed:
May. 20, 2015
Jfe Steel Corporation, Tokyo, JP;
Kazuki Fujimura, Handa, JP;
Yasuhide Ishiguro, Handa, JP;
Tetsu Nakahashi, Handa, JP;
Hideo Sato, Handa, JP;
JFE STEEL CORPORATION, Tokyo, JP;
Abstract
A high-strength seamless stainless steel pipe for oil country tubular goods that is excellent in terms of hot workability, sulfide stress cracking resistance, and corrosion resistance, and a method for manufacturing the steel pipe. The steel pipe has a chemical composition containing Cr and Ni so that the relationship Cr/Ni≤5.3 is satisfied. A microstructure of the steel pipe includes mainly a tempered martensite phase. Additionally, a surface layer microstructure of the steel pipe includes a phase which looks white when subjected to etching with a Vilella etching solution, the phase having a thickness in the wall thickness direction from the outer surface of the pipe of 10 μm or more and 100 μm or less and dispersing in the outer surface of the pipe in an amount of 50% or more in terms of area fraction.