Steel for hot working die, die for hot working, and manufacturing method for same

Abstract

Provided are a steel that is for a die and that enables production of a die being for hot working and having both high hardness and high thermal conductivity; a die for hot working; and a manufacturing method for the same. The steel for a hot working die has a compositional makeup containing, in mass %, 0.45-0.65% of C, 0.1-0.6% of Si, 0.1-2.5% of Mn, 1.0-6.0% of Cr, 1.2-3.5% of (Mo+½W) where Mo and W are contained independently or in combination, 0.1-0.5% of V, 0.15-0.6% of Ni, 0.1-0.6% of Cu, and 0.1-0.6% of Al, the balance being Fe and inevitable impurities. Further, this die for hot working has said compositional makeup, and this manufacturing method is for manufacturing said die for hot working.

1 . A steel for a hot working die having a compositional makeup containing, in mass %, 0.45-0.65% of C, 0.1-0.6% of Si, 0.1-2.5% of Mn, 1.0-6.0% of Cr, 1.2-3.5% of (Mo+½W) where Mo and W are contained independently or in combination, 0.1-0.5% of V, 0.15-0.6% of Ni, 0.1-0.6% of Cu, and 0.1-0.6% of Al, a balance being Fe and inevitable impurities. 
     
     
         2 . The steel for a hot working die according to  claim 1 ,
 wherein, when the steel has been tempered at 575° C., a hardness is 52 HRC or higher.   
     
     
         3 . A die for hot working having a compositional makeup containing, in mass %, 0.45-0.65% of C, 0.1-0.6% of Si, 0.1-2.5% of Mn, 1.0-6.0% of Cr, 1.2-3.5% of (Mo+½W) where Mo and W are contained independently or in combination, 0.1-0.5% of V, 0.15-0.6% of Ni, 0.1-0.6% of Cu, and 0.1-0.6% of Al, a balance being Fe and inevitable impurities. 
     
     
         4 . The die for hot working according to  claim 3 ,
 wherein a hardness is 52 HRC or higher, and a thermal conductivity is 25 W/(m·K) or higher.   
     
     
         5 . The die for hot working according to  claim 3 , comprising:
 a nitrided layer on a work surface.   
     
     
         6 . A manufacturing method for a die for hot working,
 wherein the steel for a hot working die according to  claim 1  is quenched at a quenching temperature of 1020-1080° C. and tempered at a tempering temperature of 540-620° C.   
     
     
         7 . The manufacturing method for a die for hot working according to  claim 6 ,
 wherein, after the quenching and the tempering, a nitriding treatment is further carried out on a work surface.   
     
     
         8 . The die for hot working according to  claim 4 , comprising:
 a nitrided layer on a work surface.   
     
     
         9 . A manufacturing method for a die for hot working,
 wherein the steel for a hot working die according to  claim 2  is quenched at a quenching temperature of 1020-1080° C. and tempered at a tempering temperature of 540-620° C.   
     
     
         10 . The manufacturing method for a die for hot working according to  claim 9 ,
 wherein, after the quenching and the tempering, a nitriding treatment is further carried out on a work surface.