MARTENSITIC STAINLESS STEEL SEAMLESS PIPE AND METHOD FOR PRODUCING MARTENSITIC STAINLESS STEEL SEAMLESS PIPE

WIPO Patent Application WO/2023/085141

A1

The present invention achieves both high yield strength and excellent pitting corrosion resistance on the inner surface. A martensitic stainless steel seamless pipe according to the present disclosure has a chemical composition described in the specification, a microstructure described in the specification, and a yield strength of 862 MPa or more. The lengths of the pipe axis direction (L direction) and the pipe diameter direction (T direction) are both 1.0 μm. An observation visual field region (50) including an inner surface (10) extending in the L direction comprises an inner surface vicinity region (20), an inner region (30) adjacent below the inner surface vicinity region, and a void region (40). When the observation visual field region (50) is divided into sections divided equally into 256 in the L direction and 256 in the T direction, an inner surface Cu occupancy rate OSCu, which is defined by the number ratio of sections having a Cu concentration greater than 2.0% in the inner surface vicinity region (20), and an inner Cu occupancy rate OICu, which is defined by the number ratio of sections having a Cu concentration greater than 2.0% in the inner region (30), satisfy formula (2).　OSCu/OICu≧1.20　(2)

KANKI KYOHEI (JP)
TAKABE HIDEKI (JP)
NISHIHARA KATSUHIRO (JP)
AMINO TAKAFUMI (JP)

PCT/JP2022/040601

May 19, 2023

October 31, 2022

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NIPPON STEEL CORP (JP)

C21D8/10; C22C38/00; C22C38/54

WO2021206080A1	2021-10-14
WO2021210564A1	2021-10-21
WO2020071344A1	2020-04-09
WO2020067247A1	2020-04-02
WO2022075406A1	2022-04-14

ASCEND IP LAW FIRM (JP)

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