Oil country tubular good for expansion in well and duplex stainless steel used for oil country tubular good for expansion

Abstract

An oil country tubular good for expansion according to the invention is expanded in a well. The oil country tubular good for expansion according to the invention is formed of duplex stainless steel having a composition containing, in percentage by mass, 0.005% to 0.03% C, 0.1% to 1.0% Si, 0.2% to 2.0% Mn, at most 0.04% P, at most 0.015% S, 18.0% to 27.0% Cr, 4.0% to 9.0% Ni, at most 0.040% Al, and 0.05% to 0.40% N, and the balance consisting of Fe and impurities, a structure including an austenite ratio in the range from 40% to 90%. The oil country tubular good for expansion according to the invention has a yield strength from 256 MPa to 655 MPa, and a uniform elongation more than 20%. Therefore, the oil country tubular good for expansion according to the invention has a high pipe expansion characteristic.

1 - 10 . (canceled) 
   
   
       11 . An oil country tubular good for expansion in a well formed of duplex stainless steel having a composition comprising, in percentage by mass, 0.005% to 0.03% C, 0.1% to 1.0% Si, 0.2% to 2.0% Mn, at most 0.04% P, at most 0.015% S, 18.0% to 27.0% Cr, 4.0% to 9.0% Ni, at most 0.040% Al, and 0.05% to 0.40% N, and the balance consisting of Fe and impurities, and a structure comprising an austenite ratio in the range from 40% to 90%,
 said oil country tubular good having a yield strength from 276 MPa to 655 MPa, and a uniform elongation more than 20%.   
   
   
       12 . The oil country tubular good for expansion according to  claim 11 , wherein said duplex stainless steel further contains at most 2.0% Cu. 
   
   
       13 . The oil country tubular good for expansion according to  claim 11 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 4.0% Mo and at most 5.0% W. 
   
   
       14 . The oil country tubular good for expansion according to  claim 12 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 4.0% Mo and at most 5.0% W. 
   
   
       15 . The oil country tubular good for expansion according to  claim 11 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.8% Ti, at most 1.5% V, and at most 1.5% Nb. 
   
   
       16 . The oil country tubular good for expansion according to  claim 12 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.8% Ti, at most 1.5% V, and at most 1.5% Nb. 
   
   
       17 . The oil country tubular good for expansion according to  claim 13 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.8% Ti, at most 1.5% V, and at most 1.5% Nb. 
   
   
       18 . The oil country tubular good for expansion according to  claim 14 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.8% Ti, at most 1.5% V, and at most 1.5% Nb. 
   
   
       19 . The oil country tubular good for expansion according to  claim 11 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca and at most 0.02% Mg. 
   
   
       20 . The oil country tubular good for expansion according to  claim 12 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca and at most 0.02% Mg. 
   
   
       21 . The oil country tubular good for expansion according to  claim 13 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca and at most 0.02% Mg. 
   
   
       22 . The oil country tubular good for expansion according to  claim 14 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca and at most 0.02% Mg. 
   
   
       23 . The oil country tubular good for expansion according to  claim 15 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca and at most 0.02% Mg. 
   
   
       24 . The oil country tubular good for expansion according to  claim 16 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca and at most 0.02% Mg. 
   
   
       25 . The oil country tubular good for expansion according to  claim 17 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca and at most 0.02% Mg. 
   
   
       26 . The oil country tubular good for expansion according to  claim 18 , wherein said duplex stainless steel further contains one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca and at most 0.02% Mg. 
   
   
       27 . Duplex stainless steel used for oil country tubular goods for expansion, comprising, in percentage by mass, 0.005% to 0.03% C, 0.1% to 1.0% Si, 0.2% to 2.0% Mn, at most 0.04% P, at most 0.015% S, 18.0% to 27.0% Cr, 4.0% to 9.0% Ni, at most 0.040% Al, and 0.05% to 0.40% N, and the balance consisting of Fe and impurities,
 said duplex stainless steel comprising an austenite ratio from 40% to 90%, and having a yield strength from 276 MPa to 655 MPa and a uniform elongation more than 20%.   
   
   
       28 . The duplex stainless steel according to  claim 27 , further comprising at most 2.0% Cu. 
   
   
       29 . The duplex stainless steel according to  claim 27 , further comprising one or more selected from the group consisting of at most 4.0% Mo and at most 5.0% W. 
   
   
       30 . The duplex stainless steel according to  claim 27 , further comprising one or more selected from the group consisting of at most 0.8% Ti, at most 1.5% V, and at most 1.5% Nb. 
   
   
       31 . The duplex stainless steel according to  claim 27 , further comprising one or more selected from the group consisting of at most 0.02% B, at most 0.02% Ca, and at most 0.02% Mg.