Cold work tool steel

Abstract

Cold work tool steel of the present invention comprises 0.4≦K value≦2.6 (K value Cr(wt %)−6.8C (wt %)), 15.5≦L value≦21.0 (L value=Cr(wt %)+15.5C (wt %), 0.60 wt %≦Si≦2.0 wt %, 0.10 wt %≦Mn≦1.0 wt %, 0.03 wt %<S≦0.2 wt %, 1.25 wt %<Mo+0.5 W<3.0 wt %, 0.05 wt %≦V≦1.0 wt %, and the balance Fe and inevitable impurities, in which the highest hardness obtained by tempering at 450° C. or higher after quenching is HRC 61 or more.

1 . Cold work tool steel comprising:  
       0.4≦K value≦2.6 (K value=Cr(wt %)−6.8 C (wt %)),  15.5 ≦L  value≦21.0 ( L  value=Cr(wt %)+15.5 C (wt %)),  0.60 wt %<Si≦2.0 wt %,  0.10 wt %≦Mn≦1.0 wt %,  0.03 wt %<S≦0.2 wt %,  1.25 wt %<Mo+0.5 W<3.0 wt %,  0.05 wt %≦V≦1.0 wt %, and  the balance Fe and inevitable impurities;    in which the highest hardness obtained by tempering at 450° C. or higher after quenching is HRC 61 or more.    
   
   
       2 . The cold work tool steel according to  claim 1 , further comprising one or more elements selected from:  
       0.005 wt %≦Se≦0.10 wt %,  0.005 wt %≦Te≦0.10 wt %,  0.0002 wt %≦Ca≦0.010 wt %,  0.005 wt %≦Pb≦0.10 wt %, and  0.005 wt %≦Bi≦0.10 wt %.  
   
   
       3 . The cold work tool steel according to  claim 1 , further comprising one or more elements selected from:  
       0.01 wt %≦Cu≦2.0 wt %,  0.01 wt %≦Ni≦2.0 wt %,    0.20  wt %≦Co≦1.0 wt %, and  0.0003 wt %≦B≦0.010 wt %.  
   
   
       4 . The cold work tool steel according to  claim 2 , further comprising one or more elements selected from:  
       0.01 wt %≦Cu≦2.0 wt %,  0.01 wt %≦Ni≦2.0 wt %,  0.20 wt %≦Co≦1.0 wt %, and  0.0003 wt %≦B≦0.010 wt %.  
   
   
       5 . The cold work tool steel according to  claim 1 , further comprising one or more elements selected from:  
       0.0010 wt %≦P≦0.030 wt %,  0.0050 wt %≦N≦0.050 wt %,  0.0010 wt %≦Al≦0.10 wt %, and  0.0002 wt %≦O≦0.010 wt %.  
   
   
       6 . The cold work tool steel according to  claim 3 , further comprising one or more elements selected from:  
       0.0010 wt %≦P≦0.030 wt %,  0.0050 wt %≦N≦0.050 wt %,  0.0010 wt %≦Al≦0.10 wt %, and  0.0002 wt %≦O≦0.010 wt %.  
   
   
       7 . The cold work tool steel according to  claim 4 , further comprising one or more elements selected from:  
       0.0010 wt %≦P≦0.030 wt %,    0.0050  wt %≦N≦0.050 wt %,  0.0010 wt %≦Al≦0.10 wt %, and  0.0002 wt %≦O≦0.010 wt %.  
   
   
       8 . The cold work tool steel according to  claim 6 , further comprising one or more elements selected from:  
       0.010 wt %≦Nb≦0.10 wt %,  0.005 wt %≦Ta≦0.10 wt %,  0.005 wt %≦Ti≦0.10 wt %,  0.005 wt %≦Zr≦0.10 wt %,  0.005 wt %≦Mg≦0.10 wt %, and  0.005 wt %≦REM≦0.10 wt %.  
   
   
       9 . The cold work tool steel according to  claim 7 , further comprising one or more elements selected from:  
       0.010 wt %≦Nb≦0.10 wt %,  0.005 wt %≦Ta≦0.10 wt %,  0.005 wt %≦Ti≦0.10 wt %,  0.005 wt %≦Zr≦0.10 wt %,  0.005 wt %≦Mg≦0.10 wt %, and  0.005 wt %≦REM≦0.10 wt %.  
   
   
       10 . The cold work tool steel according to  claim 1 , which has 0.10%≦dA60×400≦1.50%, wherein “dA60×400” is the content of inclusion measured based on a method described in JIS G0555.  
   
   
       11 . The cold work tool steel according to  claim 2 , which has 0.10%≦dA60×400≦1.50%, wherein “dA60×400” is the content of inclusion measured based on a method described in JIS G0555.  
   
   
       12 . The cold work tool steel according to  claim 3 , which has 0.10%≦dA60×400≦1.50%, wherein “dA60×400” is the content of inclusion measured based on a method described in JIS G0555.  
   
   
       13 . The cold work tool steel according to  claim 5 , which has 0.10%≦dA60×400≦1.50%, wherein “dA60×400” is the content of inclusion measured based on a method described in JIS G0555.  
   
   
       14 . The cold work tool steel according to  claim 6 , which has 0.10%≦dA60×400≦1.50%, wherein “dA60×400” is the content of inclusion measured based on a method described in JIS G0555.  
   
   
       15 . The cold work tool steel according to  claim 7 , which has 0.10%≦dA60×400≦1.50%, wherein “dA60×400” is the content of inclusion measured based on a method described in JIS G0555.  
   
   
       16 . The cold work tool steel according to  claim 9 , which has 0.10%≦dA60×400≦1.50%, wherein “dA60×400” is the content of inclusion measured based on a method described in JIS G0555.  
   
   
       17 . The cold work tool steel according to  claim 1 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       18 . The cold work tool steel according to  claim 2 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       19 . The cold work tool steel according to  claim 3 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       20 . The cold work tool steel according to  claim 5 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       21 . The cold work tool steel according to  claim 10 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       22 . The cold work tool steel according to  claim 11 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       23 . The cold work tool steel according to  claim 6 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       24 . The cold work tool steel according to  claim 12 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       25 . The cold work tool steel according to  claim 13 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       26 . The cold work tool steel according to  claim 7 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       27 . The cold work tool steel according to  claim 22 , further comprising one or more elements selected from:  
       0.01 wt %≦Cu≦2.0 wt %,  0.01 wt %≦Ni≦2.0 wt %,  0.20 wt %≦Co≦1.0 wt %, and  0.0003 wt %≦B≦0.010 wt %.  
   
   
       28 . The cold work tool steel according to  claim 14 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       29 . The cold work tool steel according to  claim 15 , which can be obtained by quenching at a temperature of 950° C. or higher and 1080° C. or lower with 3.0≦Gq≦8.0, wherein “Gq” is the grain size of the prior austenite after quenching, which is measured based on a method described in JIS G0551.  
   
   
       30 . The cold work tool steel according to  claim 28 , further comprising one or more elements selected from:  
       0.010 wt %≦Nb≦0.10 wt %,  0.005 wt %≦Ta≦0.10 wt %,  0.005 wt %≦Ti≦0.10 wt %,  0.005 wt %≦Zr≦0.10 wt %,  0.005 wt %≦Mg≦0.10 wt %, and  0.005 wt %≦REM≦0.10 wt %.