公开(公告)号：US20240417835A1

公开(公告)日：2024-12-19

申请号：US18702426

申请日：2022-10-31

Applicant: NIPPON STEEL CORPORATION

Inventor： Kyohei KANKI ,  Hideki TAKABE ,  Katsuhiro NISHIHARA ,  Takafumi AMINO

IPC: C22C38/44 ,  C21D1/18 ,  C21D8/10 ,  C21D9/08 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/46 ,  C22C38/50 ,  C22C38/52

Abstract: A martensitic stainless steel seamless pipe according to the present disclosure has a chemical composition and the microstructure described in the description, and a yield strength of 862 MPa or more. An observation field of view region which is 1.0 μm long in each of L direction and T direction and which includes an inner surface is composed of an inner surface vicinity region, an interior region that is below contact with the inner surface vicinity region, and a hollow region. An inner surface Cu occupancy OScu which is defined as the numerical proportion of sections in which a Cu concentration is more than 2.0% in the inner surface vicinity region, and an interior Cu occupancy OIcu which is defined as the numerical proportion of sections in which the Cu concentration is more than 2.0% in the interior region satisfy Formula (2). OS Cu / OI Cu ≥ 1.2 ( 2 )