Welding wire for modified 9Cr-1Mo steel, and submerged-arc welding material

Abstract

A welding wire for a modified 9Cr-1Mo steel is provided which comprises C: 0.070 to 0.150% by mass, Si: more than 0.15% by mass, but not more than 0.30% by mass, Mn: not less than 0.30% by mass, but less than 0.85% by mass, Ni: 0.30 to 1.20% by mass, Cr: 8.00 to 13.00% by mass, Mo: 0.30 to 1.40% by mass, V: 0.03 to 0.40% by mass, Nb: 0.01 to 0.15% by mass, N: 0.016 to 0.055% by mass, P: not more than 0.010% by mass, S: not more than 0.010% by mass, Cu: less than 0.50% by mass, Ti: not more than 0.010% by mass, Al: less than 0.10% by mass, B: less than 0.0010% by mass, W: less than 0.10% by mass, Co: less than 1.00% by mass, and O: not more than 0.03% by mass, wherein the total amount of Mn and Ni being not more than 1.50%. The welding wire provides good toughness without degradation of creep rupture strength even at the PWHT temperature of 760° C. or above.

1 . A welding wire consisting essentially of, by mass, 
 C: 0.070 to 0.150%,    Si: more than 0.15%, but not more than 0.30%,    Mn: not less than 0.30%, but less than 0.85%,    Ni: 0.30 to 1.20%,    Cr: 8.00 to 13.00%,    Mo: 0.30 to 1.40%,    V: 0.03 to 0.40%,    Nb: 0.01 to 0.15%,    N: 0.016 to 0.055%,    P: not more than 0.010%,    S: not more than 0.010%,    Cu: less than 0.50%,    Ti: not more than 0.010%,    Al: less than 0.10%,    B: less than 0.0010%,    W: less than 0.10%,    Co: less than 1.00%,    O: not more than 0.03%, and    balance: Fe and unavoidable impurities, the total amount of Mn and Ni being not more than 1.50%.    
   
   
       2 . The welding wire according to  claim 1 , wherein the Ni content is 0.40 to 1.00% by mass.  
   
   
       3 . The welding wire according to  claim 1 , wherein the Mo content is 0.80 to 1.10% by mass.  
   
   
       4 . The welding wire according to  claim 1 , wherein the Cu content is not more than 0.10% by mass.  
   
   
       5 . The welding wire according to  claim 1 , wherein the Al content is less than 0.05% by mass.  
   
   
       6 . A submerged-arc welding material, consisting essentially of, 
 the welding wire according to  claim 1 , and    a flux,    said flux comprising, by mass,    CaF 2 : 10 to 60%,    CaO: 2 to 25%,    MgO: 10 to 50%,    Al 2 O 3 : 2 to 30%, and    Si and SiO 2 : 6 to 30% in terms of SiO 2 .    
   
   
       7 . The welding material according to  claim 6 , wherein the Ni content of the welding wire is 0.40 to 1.00% by mass.  
   
   
       8 . The welding material according to  claim 6 , wherein the Mo content is 0.80 to 1.10% by mass.  
   
   
       9 . The welding material according to  claim 6 , wherein the Cu content is not more than 0.10% by mass.  
   
   
       10 . The welding material according to  claim 6 , wherein the Al content is less than 0.05% by mass.