Oxidation resistant, thermal conductive, and elevated temperature strength steel

Abstract

A steel alloy can comprise, consist essentially of, or consist of, in weight percent: 0.022 to 0.257 C; 0.01 to 0.085 N; 0.0 to 1.5 Ni; 0.1 to 0.7 Mn; 2.52 to 5.05 Cu; 8.67 to 14 Cr; 0.1 to 0.96 Si; 0.1 to 0.47 V; 0.4 to 2 Mo; 0 to 1.1 W; 0.0 to 0.5 Nb; 0.0 to 0.03 S; 0.0 to 0.03 P; 0.0 to 2 Co; and, balance Fe.

We claim: 
     
         1 . A steel alloy, comprising:
 0.022 to 0.257 C;   0.01 to 0.085 N;   0.0 to 1.5 Ni;   0.1 to 0.7 Mn;   2.52 to 5.05 Cu;   8.67 to 14 Cr;   0.1 to 0.96 Si;   0.1 to 0.47 V;   0.4 to 2 Mo;   0 to 1.1 W;   0.0 to 0.5 Nb;   0.0 to 0.03 S;   0.0 to 0.03 P;   0.0 to 2 Co; and,   balance Fe.   
     
     
         2 . The steel alloy of  claim 1 , comprising:
 0.05 to 0.17 C;   0.01 to 0.085 N;   0.28 to 1.25 Ni;   0.2 to 0.6 Mn;   2.52 to 4.02 Cu;   9.28 to 13 Cr;   0.1 to 0.5 Si;   0.1 to 0.47 V;   0.4 to 1 Mo;   0.15 to 0.4 Nb;   0.0 to 0.03 S;   0.0 to 0.03 P; and,   balance Fe.   
     
     
         3 . The steel alloy of  claim 1 , comprising in weight %:
 0.068 to 0.13 C;   0.01 to 0.085 N;   0.28 to 1.002 Ni;   0.2 to 0.5 Mn;   2.52 to 4.02 Cu;   10.7 to 11.88 Cr;   0.2 to 0.5 Si;   0.2 to 0.4 V;   0.4 to 0.8 Mo;   0.21 to 0.4 Nb;   0.0 to 0.03 S;   0.0 to 0.03 P; and   balance Fe.   
     
     
         4 . The steel alloy of  claim 1 , wherein 17≥Cr+Cu≥11.65. 
     
     
         5 . The steel alloy of  claim 1 , wherein 17≥Cr+Cu≥12.0. 
     
     
         6 . The steel alloy of  claim 1 , wherein 14.7≥Cu/(Ni+Mn)≥1.6. 
     
     
         7 . The steel alloy of  claim 1 , wherein 1.8≥Ni+Mn≥0.1. 
     
     
         8 . The steel alloy of  claim 1 , wherein −6≥0.64Cu−0.75Cr−1.0Ni−4.2Si−1.1W−1.3Nb+4.9C−5.3Mn−2.7V≥−14.5. 
     
     
         9 . The steel alloy of  claim 1 , wherein the ultimate tensile strength at 650° C. after quenching and tempering is greater than 360 MPa. 
     
     
         10 . The steel alloy of  claim 1 , wherein the ultimate tensile strength at 650° C. after quenching and tempering is greater than 435 MPa. 
     
     
         11 . The steel alloy of  claim 1 , wherein the Ultimate Tensile Strength (MPa) at 650° C. after thermally soaking at 650° C. for 500 h is greater than 250 MPa. 
     
     
         12 . The steel alloy of  claim 1 , wherein 8.3≥Cu/(Ni+Mn)≥1.6. 
     
     
         13 . The steel alloy of  claim 1 , wherein the Ultimate Tensile Strength (MPa) at 650° C. after quenching, tempering, and thermally soaking at 650° C. for 500 h is greater than 305 MPa. 
     
     
         14 . The steel alloy of  claim 1 , wherein the thermal diffusivity of the steel at 600° C. is greater than or equal to 4.4 mm 2  s −1  in the quenched and tempered condition. 
     
     
         15 . The steel alloy of  claim 1 , wherein 15.9≥Cr+Cu≥13.3. 
     
     
         16 . The steel alloy of  claim 1 , wherein 7.02≥Cu/(Ni+Mn)≥1.9. 
     
     
         17 . The steel alloy of  claim 1 , wherein the Ultimate Tensile Strength (MPa) at 650° C. after quenching, tempering, and thermally soaking at 650° C. for 500 h is greater than 320 MPa. 
     
     
         18 . The steel alloy of  claim 1 , wherein the oxidation mass change after 1000h of cyclic oxidation testing (1 h cycles) at 700° C. in an atmosphere of air+10% water vapor is less than or equal to 2 mg cm −2  but greater than or equal to −2 mg cm −2 . 
     
     
         19 . The steel alloy of  claim 1 , wherein the oxidation mass change after 1000 h of cyclic oxidation testing (1 h cycles) at 700° C. in an atmosphere of air+10% water vapor is less than or equal to 1 mg cm −2  but greater than or equal to −1 mg cm −2 . 
     
     
         20 . The steel alloy of  claim 1 , wherein 2.85≥0.251Cr−9.74C≥1.7.