Nickel-based alloy for hot forging die, hot forging die using same, and method for manufacturing forged product

Abstract

Provided is a Ni-based alloy for hot forging die having high compressive strength at high temperature and good oxidation resistance that is capable of suppressing work environment deterioration and shape deterioration. A Ni-based alloy for hot forging die in the present invention includes, by mass, 7.0 to 12.0% W, 4.0 to 11.0% Mo, 5.0 to 7.5% Al, and 0.5 to 7.5% Cr, and the balance of Ni with inevitable impurities. In addition, the Ni-based alloy for hot forging die may further include 0.5 to 7.0% by mass Ta and may further include one or more elements selected from, by mass, 0.001 to 0.5% Zr, 0.001 to 0.5% Hf, 0.001 to 0.2% a rare-earth element, 0.001 to 0.2% Y, and 0.001 to 0.03% Mg. The Ni-based alloy for hot forging die may have a 0.2% compressive proof strength of at least 500 MPa at a test temperature of 1000° C. and a strain rate of 10−3/sec.

1 . A Ni-based alloy for hot forging die, comprising, by mass, 7.0 to 12.0% W, 4.0 to 11.0% Mo, 5.0 to 7.5% Al, 0.5 to 7.5% Cr, and the balance of Ni with inevitable impurities. 
     
     
         2 . The Ni-based alloy for hot forging die according to  claim 1 , further comprising 0.5 to 7.0% by mass Ta. 
     
     
         3 . The Ni-based alloy for hot forging die according to  claim 1 , further comprising one or more elements selected from, by mass, 0.001 to 0.5% Zr, 0.001 to 0.5% Hf, 0.001 to 0.2% a rare-earth element, 0.001 to 0.2% Y, and 0.001 to 0.03% Mg. 
     
     
         4 . The Ni-based alloy for hot forging die according to  claim 1 , wherein a 0.2% compressive proof strength of the Ni-based alloy for hot forging die at a test temperature of 1000° C. and a strain rate of 10 −3 /sec is at least 500 MPa. 
     
     
         5 . The Ni-based alloy for hot forging die according to  claim 1 , wherein a 0.2% compressive proof strength of the Ni-based alloy for hot forging die at a test temperature of 1100° C. and a strain rate of 10 −3 /sec is at least 350 MPa. 
     
     
         6 . A hot forging die using the Ni-based alloy for hot forging die according to  claim 1 . 
     
     
         7 . The hot forging die according to  claim 6 , further comprising an antioxidant coating layer on at least one of a forming surface and a side surface of the hot forging die. 
     
     
         8 . A method for manufacturing a forged product, comprising:
 a first step of heating a forging workpiece; and   a second step of hot-forging the forging workpiece heated in the first step by using the hot forging die according to  claim 6 .   
     
     
         9 . The method for manufacturing a forged product according to  claim 8 , wherein the second step is performed with the hot forging die heated to at least 1000° C.