Sumitomo Metal Industries, Inc.

Nippon Steel Sumitomo Metal Corporation

Hitoshi Suwabe

Toshihide Ono

Masaaki Igarashi

Hisashi Amaya

Kouichi Kuroda

Masayuki Sagara

Masaki Ueyama

Naoki Sawawatari

Shigemitsu Kimura

There is provided an austenitic alloy pipe that is durable even if a stress distribution different according to usage environment is applied. The austenitic alloy pipe in accordance with the present invention has a tensile yield strength YSof at least 689.1 MPa. The tensile yield strength YS, a compressive yield strength YSin a pipe axial direction, a tensile yield strength YSin a pipe circumferential direction of the alloy pipe, and a compressive yield strength YSin the pipe circumferential direction satisfy Formulas (1) to (4).0.90&#x2266;&#x2266;1.11&#x2003;&#x2003;(1)0.90&#x2266;&#x2266;1.11&#x2003;&#x2003;(2)0.90&#x2266;&#x2266;1.11&#x2003;&#x2003;(3)0.90&#x2266;&#x2266;1.11&#x2003;&#x2003;(4)

Austenitic alloy pipe and method for producing the same

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.

Method for manufacturing a high alloy pipe

A method for producing a two-phase stainless steel pipe, which comprises:

Method for producing two-phase stainless steel pipe

A method for producing a high alloy pipe having a minimum yield strength of 758.3 to 965.2 MPa, comprising: preparing a high alloy pipe having controlled amounts of C, Si, Mn, Ni, Cr, Mo, Cu, and N, the balance being Fe and impurities by a hot working or further by a solid-solution heat treatment; and then subsequently subjecting the high alloy pipe to a cold rolling. The cold rolling is performed such that the working ratio Rd, in terms of the reduction of area, in the final cold rolling step falls within a range of larger than 30% and equal to or less than 80%, and the following formula is satisfied: Rd(%)&#x3e;(MYS&#x2212;520)/3.1&#x2212;(Cr+6&#xd7;Mo+300&#xd7;N) wherein Rd and MYS signify the working ratio (%) in terms of the reduction of area and the targeted yield strength (MPa), respectively, and Cr, Mo and N signify the mass % of the individual elements.

Method for producing high alloy pipe

A method for producing a duplex stainless steel pipe having a minimum yield strength of 758.3 to 965.2 MPa, comprises first hot working and optionally solution heat treating a duplex stainless steel material pipe having a chemical composition consisting, by mass %, of C: 0.03% or less, Si: 1% or less, Mn: 0.1 to 4%, Cr: 20 to 35%, Ni: 3 to 10%, Mo: 0 to 6%, W: 0 to 6%, Cu: 0 to 3% and N: 0.15 to 0.60%, the balance being Fe and impurities. The pipe is then cold rolled under conditions that the working ratio Rd, in terms of the reduction of area, in the final cold rolling step falls within a range from 10 to 80%, and formula (1) is satisfied:=exp[{In()&#x2212;In(14.5&#xd7;Cr+48.3&#xd7;Mo+20.7&#xd7;W+6.9&#xd7;N)}/0.195]&#x2003;&#x2003;(1)wherein Rd is a reduction in area %, MYS is the targeted yield strength (MPa), and Cr, Mo, W and N are in mass %.

Growing community of inventors

Itami, Japan

Hitoshi Suwabe