Nippon Steel Sumitomo Metal Corporation

Noriaki Onodera

Kazutoshi Ichikawa

Teruyuki Wakatsuki

Hidetoshi Ito

Kohichi Yamamoto

In a steel sheet pile according to the present invention, a carbon equivalent CEis 0.260 to 0.500, a structure includes a ferrite, a pearlite, a Widmanst&#xe4;tten ferrite, and a precipitate, the precipitate is one or both of Nb carbonitride and V carbonitride, a total number density of the precipitate is 0.10 to 0.30 pieces/&#x3bc;m, a total area ratio of the ferrite and the pearlite is 70% or more, an area ratio of the Widmanst&#xe4;tten ferrite is 1% or more, an average grain size of the ferrite and the pearlite is 10 to 80 &#x3bc;m, and a yield strength is 460 MPa or more.

Steel sheet pile and method for manufacturing the same

This H-beam steel contains, in mass %, C, Si, Mn, Al, Ti, N, O, Nb, and B. The H-beam steel has composition in which the amount of Nb and the amount of B satisfy, in mass %, 0.070&#x2266;Nb+125B&#x2266;0.155, and has a metal structure in which, in a microstructure, an area fraction of bainite is not less than 70%, a total of an area fraction of pearlite and an area fraction of cementite is not more than 15%, and the remainder is at least one of ferrite and island martensite. The effective crystalline-grain size of the bainite is not more than 40 &#x3bc;m, and the thickness of a flange falls in a range of 12 to 40 mm.

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Osaka, Japan

Noriaki Onodera