Nippon Steel Sumitomo Metal Corporation

Shigemitsu Kimura

Masaaki Igarashi

Hisashi Amaya

Masayuki Sagara

Hitoshi Suwabe

A method for manufacturing a high alloy pipe comprises hot working, a high alloy material pipe having controlled amounts of C, Si, Mn, P, S, Ni, Cr, Mo, Cu, Al, N, O, and optionally Ca, Mg, and rare earth elements, with the balance Fe. The pipe composition satisfies the formula N&#xd7;O&#x2266;0.001. The pipe is subjected to cold working to form the high alloy pipe, wherein the final cold working process is performed under the condition that a working ratio Rd in the reduction of area satisfies 15&#x2266;Rd (%)&#x2266;370&#xd7;(C+N), where N, O and C are the contents (by mass percent) of the respective elements, and Rd is the working ratio (%) in the reduction of area. The pipe has an excellent ductility and an excellent corrosion resistance when cold working is performed to obtain a high strength after pipe-making.

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Nishinomiya, Japan

Shigemitsu Kimura