Austenitic stainless steel

Abstract

An austenitic stainless steel with a chemical composition including in terms of mass %: 0.05 to 0.13% of C, 0.10 to 1.00% of Si, 0.10 to 3.00% of Mn, 0.040% or less of P, 0.020% or less of S, 17.00 to 19.00% of Cr, 12.00 to 15.00% of Ni, 2.00 to 4.00% of Cu, 0.01 to 2.00% of Mo, 2.00 to 5.00% of W, 2.50 to 5.00% of 2Mo+W, 0.01 to 0.40% of V, 0.05 to 0.50% of Ti, 0.15 to 0.70% of Nb, 0.001 to 0.040% of Al, 0.0010 to 0.0100% of B, 0.0010 to 0.0100% of N, 0.001 to 0.20% of Nd, 0.002% or less of Zr, 0.001% or less of Bi, 0.010% or less of Sn, 0.010% or less of Sb, 0.001% or less of Pb, 0.001% or less of As, 0.020% or less of Zr+Bi+Sn+Sb+Pb+As, 0.0090% or less of O, and a remainder including Fe and impurities.

1 . An austenitic stainless steel with a chemical composition consisting of in terms of mass %:
 0.05 to 0.13% of C,   0.10 to 1.00% of Si,   0.10 to 3.00% of Mn,   0.040% or less of P,   0.020% or less of S,   17.00 to 19.00% of Cr,   12.00 to 15.00% of Ni,   2.00 to 4.00% of Cu,   0.01 to 2.00% of Mo,   2.00 to 5.00% of W,   2.50 to 5.00% of 2Mo+W,   0.01 to 0.40% of V,   0.05 to 0.50% of Ti,   0.15 to 0.70% of Nb,   0.001 to 0.040% of Al,   0.0010 to 0.0100% of B,   0.0010 to 0.0100% of N,   0.001 to 0.20% of Nd,   0.002% or less of Zr,   0.001% or less of Bi,   0.010% or less of Sn,   0.010% or less of Sb,   0.001% or less of Pb,   0.001% or less of As,   0.020% or less of Zr+Bi+Sn+Sb+Pb+As,   0.0090% or less of O,   0.80% or less of Co,   0.20% or less of Ca,   0.20% or less of Mg,   0.20% or less in total of one or more of Y, Sc, Ta, Hf, Re or lanthanoid elements other than Nd, and   a remainder consisting of Fe and impurities;
 wherein an effective M content Meff defined by the following Formula (1) is 0.0001 to 0.250%:
   Effective M content Meff=Nd+13·(B−11·N/14)−1.6·Zr  Formula (1)
 
 
 wherein in Formula (1), each element symbol represents a content (mass %) of each element. 
   
     
     
         2 . The austenitic stainless steel according to  claim 1 , wherein the chemical composition comprises, in terms of mass %, one or more of: 0.01 to 0.80% of Co, 0.0001 to 0.20% of Ca, or 0.0005 to 0.20% of Mg. 
     
     
         3 . The austenitic stainless steel according to  claim 1 , wherein the chemical composition comprises, in terms of mass %, 0.001 to 0.20% in total of one or more of Y, Sc, Ta, Hf, Re or lanthanoid elements other than Nd. 
     
     
         4 . The austenitic stainless steel according to  claim 1 , wherein an ASTM grain size number of a metallic structure thereof is 7 or less. 
     
     
         5 . The austenitic stainless steel according to  claim 1 , wherein a creep rupture strength at 700° C. and 10,000 hours is 140 MPa or more. 
     
     
         6 . The austenitic stainless steel according to  claim 1 , wherein the effective M content Meff is 0.002 to 0.250%. 
     
     
         7 . The austenitic stainless steel according to  claim 2 , wherein the chemical composition comprises, in terms of mass %, 0.001 to 0.20% in total of one or more of Y, Sc, Ta, Hf, Re or lanthanoid elements other than Nd. 
     
     
         8 . The austenitic stainless steel according to  claim 2 , wherein an ASTM grain size number of a metallic structure thereof is 7 or less. 
     
     
         9 . The austenitic stainless steel according to  claim 2 , wherein a creep rupture strength at 700° C. and 10,000 hours is 140 MPa or more. 
     
     
         10 . The austenitic stainless steel according to  claim 2 , wherein the effective M content Meff is 0.002 to 0.250%. 
     
     
         11 . The austenitic stainless steel according to  claim 3 , wherein an ASTM grain size number of a metallic structure thereof is 7 or less. 
     
     
         12 . The austenitic stainless steel according to  claim 3 , wherein a creep rupture strength at 700° C. and 10,000 hours is 140 MPa or more. 
     
     
         13 . The austenitic stainless steel according to  claim 3 , wherein the effective M content Meff is 0.002 to 0.250%. 
     
     
         14 . An austenitic stainless steel with a chemical composition comprising in terms of mass %:
 0.05 to 0.13% of C,   0.10 to 1.00% of Si,   0.10 to 3.00% of Mn,   0.040% or less of P,   0.020% or less of S,   17.00 to 19.00% of Cr,   12.00 to 15.00% of Ni,   2.00 to 4.00% of Cu,   0.01 to 2.00% of Mo,   2.00 to 5.00% of W,   2.50 to 5.00% of 2Mo+W,   0.01 to 0.40% of V,   0.05 to 0.50% of Ti,   0.15 to 0.70% of Nb,   0.001 to 0.040% of Al,   0.0010 to 0.0100% of B,   0.0010 to 0.0100% of N,   0.001 to 0.20% of Nd,   0.002% or less of Zr,   0.001% or less of Bi,   0.010% or less of Sn,   0.010% or less of Sb,   0.001% or less of Pb,   0.001% or less of As,   0.020% or less of Zr+Bi+Sn+Sb+Pb+As,   0.0090% or less of O,   0.80% or less of Co,   0.20% or less of Ca,   0.20% or less of Mg,   0.20% or less in total of one or more of Y, Sc, Ta, Hf, Re or lanthanoid elements other than Nd, and   a remainder comprising Fe and impurities;
 wherein an effective M content Meff defined by the following Formula (1) is 0.0001 to 0.250%:
   Effective M content Meff=Nd+13·(B−11·N/14)−1.6·Zr  Formula (1)
 
 
 wherein in Formula (1), each element symbol represents a content (mass %) of each element. 
   
     
     
         15 . The austenitic stainless steel according to  claim 14 , wherein the chemical composition comprises, in terms of mass %, one or more of: 0.01 to 0.80% of Co, 0.0001 to 0.20% of Ca, or 0.0005 to 0.20% of Mg. 
     
     
         16 . The austenitic stainless steel according to  claim 14 , wherein the chemical composition comprises, in terms of mass %, 0.001 to 0.20% in total of one or more of Y, Sc, Ta, Hf, Re or lanthanoid elements other than Nd. 
     
     
         17 . The austenitic stainless steel according to  claim 14 , wherein an ASTM grain size number of a metallic structure thereof is 7 or less. 
     
     
         18 . The austenitic stainless steel according to  claim 14 , wherein a creep rupture strength at 700° C. and 10,000 hours is 140 MPa or more. 
     
     
         19 . The austenitic stainless steel according to  claim 14 , wherein the effective M content Meff is 0.002 to 0.250%.