Nippon Steel Corporation

Kosei Kato

Yusaku Tomio

The duplex stainless seamless steel pipe according to the present disclosure has the chemical composition described in the description and a microstructure composed of 30.0 to 70.0% of ferrite, and austenite. In an observation field of view region of a square shape with a side of 1.0 mm, the region including a center portion of wall thickness and including an L direction and a T direction. A number of intersections NT, which is the number of intersections between the line segments Tto Twhich is four line segments extending in the T direction and a ferrite interface, is 40.0 or more. A number of intersections NL, which is the number of intersections between the line segments Lto Lwhich is four line segments extending in the L direction and the ferrite interface, and the number of intersections NT satisfy Formula (1).≥2.0  (1)

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Tokyo, Japan

Kosei Kato