Heat-resistant steel

Abstract

Disclosed is a ferritic heat-resistant steel which has the following chemical composition (by weight): C: from 0.01% to less than 0.08%; Si: 0.30-1.0%; P: 0.02 or less; S: 0.010% or less; Mn: 0.2-1.2%; Ni: 0.3% or less; Cr: 8.0-11.0%; Mo: 0.1-1.2%; W: 1.0-2.5%; V: 0.10-0.30%; Nb: 0.02-0.12%; Co: 0.01-4.0%; N: 0.01-0.08%; B: not less than 0.001% and less than 0.010%; Cu: 0.3% or less; and Al: 0.010% or less, provided that the chemical composition satisfies the following equations: Mo(%)+0.5×W(%)=1.0-1.6, and C(%)+N(%)=0.02-0.15%, and which comprises a tempered martensite single-phase tissue produced by thermal refining and contains 30% by weight or less of 5 ferrite.

1 . A heat-resistant steel which has the following chemical composition (by weight): carbon (C): 0.01-0.08%; silicon (Si): 0.30-1.0%; phosphorus (P): 0.020% or less; sulfur (S): 0.010% or less; manganese (Mn): 0.2-1.2%; nickel (Ni): 0.3% or less; chromium (Cr): 8.0-11.0%, molybdenum (Mo): 0.1-1.2%; tungsten (W): 1.0-2.02%; vanadium (V): 0.10-0.30%; niobium (Nb): 0.02-0.12%; cobalt (Co): 0.01-4.0%; nitrogen (N): 0.01-0.08%; boron (B): not less than 0.001% and not more than 0.010%; copper (Cu): 0.3% or less; aluminum (Al): 0.010% or less; provided that the amount of (Mo %+0.5W %) is 1.0-1.6, and the amount of (C %+N %) is 0.02-0.15%, and which comprises a tempered martensite single-phase tissue produced by thermal refining. 
     
     
         2 . The heat-resistant steel according to  claim 1 , having the chemical composition in which the amount of (Al %+0.1×Ni %) is 0.02% by weight or less. 
     
     
         3 . The heat-resistant steel according to  claim 1 , comprising from 0.01% to 0.075% carbon. 
     
     
         4 . The heat-resistant steel according to  claim 2 , comprising from 0.01% to 0.075% carbon. 
     
     
         5 . The heat-resistant steel according to  claim 1 , comprising 0.40-0.75% by weight of Si. 
     
     
         6 . The heat-resistant steel according to  claim 2 , comprising 0.40-0.75% by weight of Si. 
     
     
         7 . The heat-resistant steel according to  claim 3 , comprising 0.40-0.75% by weight of Si. 
     
     
         8 . The heat-resistant steel according to  claim 4 , comprising 0.40-0.75% by weight of Si. 
     
     
         9 . The heat-resistant steel according to  claim 1 , further comprising (by weight) at least one of <0.2% Ta, <0.1% Ti, <0.2% Zr, <0.1% La, <0.1% Ce, <0.2% Pd, <0.5% Re, <0.3% Hf. 
     
     
         10 . The heat-resistant steel according to  claim 2 , further comprising (by weight) at least one of <0.2% Ta, <0.1% Ti, <0.2% Zr, <0.1% La, <0.1% Ce, <0.2% Pd, <0.5% Re, <0.3% Hf. 
     
     
         11 . The heat-resistant steel according to  claim 3 , further comprising (by weight) at least one of <0.2% Ta, <0.1% Ti, <0.2% Zr, <0.1% La, <0.1% Ce, <0.2% Pd, <0.5% Re, <0.3% Hf. 
     
     
         12 . The heat-resistant steel according to  claim 4 , further comprising (by weight) at least one of <0.2% Ta, <0.1% Ti, <0.2% Zr, <0.1% La, <0.1% Ce, <0.2% Pd, <0.5% Re, <0.3% Hf. 
     
     
         13 . The heat-resistant steel according to  claim 5 , further comprising (by weight) at least one of <0.2% Ta, <0.1% Ti, <0.2% Zr, <0.1% La, <0.1% Ce, <0.2% Pd, <0.5% Re, <0.3% Hf. 
     
     
         14 . The heat-resistant steel according to  claim 6 , further comprising (by weight) at least one of <0.2% Ta, <0.1% Ti, <0.2% Zr, <0.1% La, <0.1% Ce, <0.2% Pd, <0.5% Re, <0.3% Hf. 
     
     
         15 . The heat-resistant steel according to  claim 7 , further comprising (by weight) at least one of <0.2% Ta, <0.1% Ti, <0.2% Zr, <0.1% La, <0.1% Ce, <0.2% Pd, <0.5% Re, <0.3% Hf. 
     
     
         16 . The heat-resistant steel according to  claim 8 , further comprising (by weight) at least one of <0.2% Ta, <0.1% Ti, <0.2% Zr, <0.1% La, <0.1% Ce, <0.2% Pd, <0.5% Re, <0.3% Hf.