Steel for a plastic molding die

Abstract

To provide a steel for plastic molding die which possesses enough hardness, wear resistance and corrosion resistance, and is excellent in high-precision processability and mirror polishing properties. The steel for a plastic molding die contains not more than 0.80 wt % C, not less than 0.01 wt % and less than 1.40 wt % Si, not less than 0.05 wt % and not more than 2.0 wt % Mn, not less than 0.005 wt % and not more than 1.00 wt % Ni, not less than 13.0 wt % and not more than 20.0 wt % Cr, not less than 0.20 wt % and not more than 4.0 wt % Mo+½ W, not less than 0.01 wt % and not more than 1.00 wt % V, not less than 0.36 wt % and not more than 0.80 wt % N, not more than 0.02 wt % O, not more than 0.80 wt % Al, and the remainder substantially including Fe and unavoidable impurities.

1 . A steel for a plastic molding die comprising: 
 not more than 0.80 wt % C;    not less than 0.01 wt % and less than 1.40 wt % Si;    not less than 0.05 wt % and not more than 2.0 wt % Mn;    not less than 0.005 wt % and not more than 1.00 wt % Ni;    not less than 13.0 wt % and not more than 20.0 wt % Cr;    not less than 0.20 wt % and not more than 4.0 wt % Mo+½ W;    not less than 0.01 wt % and not more than 1.00 wt % V;    not less than 0.36 wt % and not more than 0.80 wt % N;    not more than 0.02 wt % O;    not more than 0.80 wt % Al; and    the remainder substantially including Fe and unavoidable impurities.    
   
   
       2 . The steel for a plastic molding die according to  claim 1  further comprising at least one element selected from the group consisting of: 
 not more than 0.030 wt % P; and    not more than 0.030 wt % S.    
   
   
       3 . The steel for a plastic molding die according to  claim 2  further comprising at least one element selected from the group consisting of: 
 not less than 0.001 wt % and not more than 0.50 wt % Cu;    not less than 0.001 wt % and not more than 0.50 wt % Co; and    not less than 0.0005 wt % and not more than 0.010 wt % B.    
   
   
       4 . The steel for a plastic molding die according to  claim 3  further comprising at least one element selected from the group consisting of: 
 not less than 0.001 wt % and not more than 0.30 wt % Se;    not less than 0.001 wt % and not more than 0.30 wt % Te;    not less than 0.001 wt % and not more than 0.10 wt % Ca;    not less than 0.001 wt % and not more than 0.20 wt % Pb; and    not less than 0.001 wt % and not more than 0.30 wt % Bi.    
   
   
       5 . The steel for a plastic molding die according to  claim 4  further comprising at least one element selected from the group consisting of: 
 not more than 0.20 wt % Ti;    not less than 0.001 wt % and not more than 0.30 wt % Nb;    not less than 0.001 wt % and not more than 0.30 wt % Ta; and    not less than 0.001 wt % and not more than 0.30 wt % Zr.    
   
   
       6 . The steel for a plastic molding die according to  claim 3  further comprising at least one element selected from the group consisting of: 
 not more than 0.20 wt % Ti;    not less than 0.001 wt % and not more than 0.30 wt % Nb;    not less than 0.001 wt % and not more than 0.30 wt % Ta; and    not less than 0.001 wt % and not more than 0.30 wt % Zr.    
   
   
       7 . The steel for a plastic molding die according to  claim 2  further comprising at least one element selected from the group consisting of: 
 not less than 0.001 wt % and not more than 0.30 wt % Se;    not less than 0.001 wt % and not more than 0.30 wt % Te;    not less than 0.001 wt % and not more than 0.10 wt % Ca;    not less than 0.001 wt % and not more than 0.20 wt % Pb; and    not less than 0.001 wt % and not more than 0.30 wt % Bi.    
   
   
       8 . The steel for a plastic molding die according to  claim 7  further comprising at least one element selected from the group consisting of: 
 not more than 0.20 wt % Ti;    not less than 0.001 wt % and not more than 0.30 wt % Nb;    not less than 0.001 wt % and not more than 0.30 wt % Ta; and    not less than 0.001 wt % and not more than 0.30 wt % Zr.    
   
   
       9 . The steel for a plastic molding die according to  claim 2  further comprising at least one element selected from the group consisting of: 
 not more than 0.20 wt % Ti;    not less than 0.001 wt % and not more than 0.30 wt % Nb;    not less than 0.001 wt % and not more than 0.30 wt % Ta; and    not less than 0.001 wt % and not more than 0.30 wt % Zr.    
   
   
       10 . The steel for a plastic molding die according to  claim 1  further comprising at least one element selected from the group consisting of: 
 not less than 0.001 wt % and not more than 0.50 wt % Cu;    not less than 0.001 wt % and not more than 0.50 wt % Co; and    not less than 0.0005 wt % and not more than 0.010 wt % B.    
   
   
       11 . The steel for a plastic molding die according to  claim 10  further comprising at least one element selected from the group consisting of: 
 not less than 0.001 wt % and not more than 0.30 wt % Se;    not less than 0.001 wt % and not more than 0.30 wt % Te;    not less than 0.001 wt % and not more than 0.10 wt % Ca;    not less than 0.001 wt % and not more than 0.20 wt % Pb; and    not less than 0.001 wt % and not more than 0.30 wt % Bi.    
   
   
       12 . The steel for a plastic molding die according to  claim 11  further comprising at least one element selected from the group consisting of: 
 not more than 0.20 wt % Ti;    not less than 0.001 wt % and not more than 0.30 wt % Nb;    not less than 0.001 wt % and not more than 0.30 wt % Ta; and    not less than 0.001 wt % and not more than 0.30 wt % Zr.    
   
   
       13 . The steel for a plastic molding die according to  claim 10  further comprising at least one element selected from the group consisting of: 
 not more than 0.20 wt % Ti;    not less than 0.001 wt % and not more than 0.30 wt % Nb;    not less than 0.001 wt % and not more than 0.30 wt % Ta; and    not less than 0.001 wt % and not more than 0.30 wt % Zr.    
   
   
       14 . The steel for a plastic molding die according to  claim 1  further comprising at least one element selected from the group consisting of: 
 not less than 0.001 wt % and not more than 0.30 wt % Se;    not less than 0.001 wt % and not more than 0.30 wt % Te;    not less than 0.001 wt % and not more than 0.10 wt % Ca;    not less than 0.001 wt % and not more than 0.20 wt % Pb; and    not less than 0.001 wt % and not more than 0.30 wt % Bi.    
   
   
       15 . The steel for a plastic molding die according to  claim 14  further comprising at least one element selected from the group consisting of: 
 not more than 0.20 wt % Ti;    not less than 0.001 wt % and not more than 0.30 wt % Nb;    not less than 0.001 wt % and not more than 0.30 wt % Ta; and    not less than 0.001 wt % and not more than 0.30 wt % Zr.    
   
   
       16 . The steel for a plastic molding die according to  claim 1  further comprising at least one element selected from the group consisting of: 
 not more than 0.20 wt % Ti;    not less than 0.001 wt % and not more than 0.30 wt % Nb;    not less than 0.001 wt % and not more than 0.30 wt % Ta; and    not less than 0.001 wt % and not more than 0.30 wt % Zr.