Duplex stainless steel seamless pipe and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-2022018007-A1
Application number	US-201917296626-A
Country	US
Kind code	A1
Filing date	Nov 1, 2019
Priority date	Nov 30, 2018
Publication date	Jan 20, 2022
Grant date	—

Abstract

Provided herein is a duplex stainless steel seamless pipe and a method for manufacturing the same. The duplex stainless steel seamless pipe has a composition comprising, in mass %, C: 0.005 to 0.08%, Si: 0.01 to 1.0%, Mn: 0.01 to 10.0%, Cr: 20 to 35%, Ni: 1 to 15%, Mo: 0.5 to 6.0%, N: 0.150 to less than 0.400%, and one, two or more selected from Ti: 0.0001 to 0.3%, Al: 0.0001 to 0.3%, V: 0.005 to 1.5%, Nb: 0.005 to less than 1.5%, and the balance being Fe and incidental impurities. The duplex stainless steel seamless pipe contains N, Ti, Al, V, and Nb so as to satisfy the following formula (1). The duplex stainless steel seamless pipe has an axial tensile yield strength of 757 MPa or more, and a ratio of 0.85 to 1.15 as a fraction of axial compressive yield strength to axial tensile yield strength.0.150>N−(1.58Ti+2.70Al+1.58V+1.44Nb) . . .   (1),wherein N, Ti, Al, V, and Nb represent the content of each element in mass %.

First claim

1 .- 10 . (canceled)

11 . A duplex stainless steel seamless pipe of a composition comprising, in mass %, C: 0.005 to 0.08%, Si: 0.01 to 1.0%, Mn: 0.01 to 10.0%, Cr: 20 to 35%, Ni: 1 to 15%, Mo: 0.5 to 6.0%, N: 0.150 to less than 0.400%, and one, two or more selected from Ti: 0.0001 to 0.3%, Al: 0.0001 to 0.3%, V: 0.005 to 1.5%, Nb: 0.005 to less than 1.5%, and the balance being Fe and incidental impurities,
the duplex stainless steel seamless pipe containing N, Ti, Al, V, and Nb so as to satisfy the following formula (1), the duplex stainless steel seamless pipe having an axial tensile yield strength of 757 MPa or more, and a ratio of 0.85 to 1.15 as a fraction of axial compressive yield strength to axial tensile yield strength,
0.150>N−(1.58Ti+2.70Al+1.58V+1.44Nb)   (1),

wherein N, Ti, Al, V, and Nb represent the content of each element in mass % and the content is 0 (zero) percent for elements that are not contained.

12 . The duplex stainless steel seamless pipe according to claim 11 , which has a ratio of 0.85 or more as a fraction of circumferential compressive yield strength to axial tensile yield strength.

13 . The duplex stainless steel seamless pipe according to claim 11 , which further comprises one or more of the following groups A and B:
Group A: in mass %, one or two selected from W: 0.1 to 6.0%, and Cu: 0.1 to 4.0%; and Group B: in mass %, one, two or more selected from B: 0.0001 to 0.010%, Zr: 0.0001 to 0.010%, Ca: 0.0001 to 0.010%, Ta: 0.0001 to 0.3%, and REM: 0.0001 to 0.010%.

14 . The duplex stainless steel seamless pipe according to claim 12 , which further comprises one or more of the following groups A and B:
Group A: in mass %, one or two selected from W: 0.1 to 6.0%, and Cu: 0.1 to 4.0%; and Group B: in mass %, one, two or more selected from B: 0.0001 to 0.010%, Zr: 0.0001 to 0.010%, Ca: 0.0001 to 0.010%, Ta: 0.0001 to 0.3%, and REM: 0.0001 to 0.010%.

15 . A method for manufacturing the duplex stainless steel seamless pipe of claim 11 ,
the method comprising stretching along a pipe axis direction followed by a heat treatment at a heating temperature of 150 to 600° C., excluding 460 to 480° C.

16 . A method for manufacturing the duplex stainless steel seamless pipe of claim 13 ,
the method comprising stretching along a pipe axis direction followed by a heat treatment at a heating temperature of 150 to 600° C., excluding 460 to 480° C.

17 . A method for manufacturing the duplex stainless steel seamless pipe of claim 11 ,
the method comprising stretching along a pipe axis direction at a temperature of 150 to 600° C., excluding 460 to 480° C.

18 . A method for manufacturing the duplex stainless steel seamless pipe of claim 13 ,
the method comprising stretching along a pipe axis direction at a temperature of 150 to 600° C., excluding 460 to 480° C.

19 . The method according to claim 17 , wherein the stretching is followed by a heat treatment at a heating temperature of 150 to 600° C., excluding 460 to 480° C.

20 . The method according to claim 18 , wherein the stretching is followed by a heat treatment at a heating temperature of 150 to 600° C., excluding 460 to 480° C.

21 . A method for manufacturing the duplex stainless steel seamless pipe of claim 11 , the method comprising circumferential bending and rebending.

22 . A method for manufacturing the duplex stainless steel seamless pipe of claim 13 , the method comprising circumferential bending and rebending.

23 . The method according to claim 21 , wherein the circumferential bending and rebending is performed at a temperature of 600° C. or less, excluding 460 to 480° C.

24 . The method according to claim 22 , wherein the circumferential bending and rebending is performed at a temperature of 600° C. or less, excluding 460 to 480° C.

25 . The method according to claim 21 , wherein the bending and rebending is followed by a heat treatment at a heating temperature of 150 to 600° C., excluding 460 to 480° C.

26 . The method according to claim 22 , wherein the bending and rebending is followed by a heat treatment at a heating temperature of 150 to 600° C., excluding 460 to 480° C.

27 . The method according to claim 23 , wherein the bending and rebending is followed by a heat treatment at a heating temperature of 150 to 600° C., excluding 460 to 480° C.

28 . The method according to claim 24 , wherein the bending and rebending is followed by a heat treatment at a heating temperature of 150 to 600° C., excluding 460 to 480° C.

Assignees

• Jfe Steel Corp

Inventors

• Sasaki Shunsuke
• Katsumura Tatsuro
• Ota Hiroki
• Fujimura Kazuki
• Yuga Masao

Classifications

• C21D8/10

  during manufacturing of tubular bodies · CPC title

• C22C38/001

  containing N · CPC title

• C22C38/44

  with molybdenum or tungsten · CPC title

• C22C38/48

  with niobium or tantalum · CPC title

• C22C38/42

  with copper · CPC title