Steel for hot stamp die, hot stamp die and manufacturing method thereof

Abstract

A die steel which enables manufacturing a hot stamp die that has both high hardness and high thermal conductivity, a hot stamp die, and a manufacturing method thereof are provided. This steel for a hot stamp die has a component composition, in mass% of 0.45-0.65% C, 0.1-0.6% Si, 0.1-0.3% Mn, 2.5-6.0% Cr, 1.2-2.6% Mo, and 0.4-0.8% V, the remainder being Fe and unavoidable impurities. Further, this hot stamp die has the aforementioned component composition, and the manufacturing method is for manufacturing said hot stamp die.

1 . A steel for a hot stamp die having a component composition including, in mass %, C: 0.45 to 0.65%, Si: 0.1 to 0.6%, Mn: 0.1 to 0.3%, Cr: 2.5 to 6.0%, Mo: 1.2 to 2.6%, V: 0.4 to 0.8%, the remainder being Fe and unavoidable impurities. 
     
     
         2 . A hot stamp die having a component composition including, in mass%, C: 0.45 to 0.65%, Si: 0.1 to 0.6%, Mn: 0.1 to 0.3%, Cr: 2.5 to 6.0%, Mo: 1.2 to 2.6%, V: 0.4 to 0.8%, the remainder being Fe and unavoidable impurities. 
     
     
         3 . The hot stamp die according to  claim 2 ,
 wherein the hardness is 45 HRC or more, and the thermal conductivity λ(W/(m·K)) satisfies the following Formula (1):
   λ≥−0.5 H+ 53  Formula (1)
 
   
       H: Rockwell hardness (HRC) of die 
     
     
         4 . The hot stamp die according to  claim 3 ,
 wherein the hardness is 52 HRC or more.   
     
     
         5 . The hot stamp die according to  claim 4 ,
 wherein the thermal conductivity λ is 25 W/(m·K) or more.   
     
     
         6 . The hot stamp die according to  claim 2 ,
 wherein a working surface has a nitrided layer.   
     
     
         7 . A method of manufacturing a hot stamp die, comprising
 quenching and tempering the steel for a hot stamp die according to  claim 1  at a quenching temperature of 1,020 to 1,080° C. and a tempering temperature of 500 to 625° C.   
     
     
         8 . The method of manufacturing a hot stamp die according to  claim 7 ,
 wherein the tempering temperature is 540 to 600° C.   
     
     
         9 . The method of manufacturing a hot stamp die according to  claim 7 ,
 wherein, after the quenching and tempering are performed, a working surface is additionally subjected to a nitriding treatment.