Ni-Based Alloy Product and Method for Producing Same, and Ni-Based Alloy Member and Method for Producing Same

Abstract

There are provided: an Ni-based alloy member including a γ′ phase precipitation with 36 to 60 volume % and exhibiting a high durable temperature and good cold workability; a method for producing the member; an Ni-based alloy product to be used as a precursor of the member; and a method for producing the product. The Ni-based alloy product has a two-phase structure composed of a γ phase and a γ′ phase being incoherent to the γ phase, the incoherent γ′ phase being present at a ratio of 20 volume % or higher. The Ni-based alloy member produced by cold working the Ni-based alloy product and subsequently by conducting heat treatment comprises a γ phase and a γ′ phase being coherent to the γ phase, the coherent γ′ phase being present at a ratio of 36 to 60 volume %, and has a predetermined shape.

1 . A method for producing an Ni-based alloy product having a two-phase structure composed of crystalline grains of a γ phase and crystalline grains of the γ′ phase, in which the γ′ phase is an incoherent γ′ phase being located through γ phase grain boundaries of an incoherent interface, and in which the incoherent γ′ phase is present at a ratio of 20 volume % or higher in the two-phase structure, the method comprising:
 the step of melting and casting a first Ni-based alloy material to produce a second Ni-based alloy material; and 
 the step of hot-forging the second Ni-based alloy material obtained through the melting and casting step at temperatures equal to or higher than 1000° C. and wherein the γ and the γ′ phases coexist to produce a third Ni-based alloy material having an ingredient composition in which a γ′ phase at a ratio of 36 to 60 volume % can be precipitated in a temperature range of 700 to 900° C.; and 
 the step of forming the Ni-based alloy product from the third Ni-based alloy material. 
 
     
     
         2 . The method for producing an Ni-based alloy product according to  claim 1 ,
 wherein the γ′ phase precipitates at a ratio of 10 volume % or higher in the hot-forging step.   
     
     
         3 . The method for producing an Ni-based alloy product according to  claim 1 ,
 wherein the method further comprises the step of subjecting the third Ni-based alloy material obtained through the hot-forging step to a homogenization heat treatment prior to forming the Ni-based alloy product by (1) holding a temperature equal to or higher than 1000° C. but equal to or lower than the hot-forging temperature and wherein the γ and the γ′ phases coexist, and (2) slow-cooling to a temperature by 100° C. or more below the holding temperature.   
     
     
         4 . The method for producing an Ni-based alloy product according to  claim 2 ,
 wherein the method further comprises the step of subjecting the third Ni-based alloy material obtained through the hot-forging step to a homogenization heat treatment prior to forming the Ni-based alloy product by (1) holding a temperature equal to or higher than 1000° C. but equal to or lower than the hot-forging temperature and wherein the γ and the γ′ phases coexist, and (2) slow-cooling to a temperature by 100° C. or more below the holding temperature.   
     
     
         5 . The method for producing an Ni-based alloy product according to  claim 3 ,
 wherein a rate of the slow-cooling in the homogenization heat treatment is equal to or slower than 100° C./h.   
     
     
         6 . The method for producing an Ni-based alloy product according to  claim 5 ,
 wherein a rate of the slow-cooling in the homogenization heat treatment is 5° C./h or more and 50° C./h or less.   
     
     
         7 . The method for producing an Ni-based alloy product according to  claim 4 ,
 wherein a rate of the slow-cooling in the homogenization heat treatment is equal to or slower than 100° C./h.   
     
     
         8 . The method for producing an Ni-based alloy product according to  claim 7 ,
 wherein a rate of the slow-cooling in the homogenization heat treatment is 5° C./h or more and 50° C./h or less.   
     
     
         9 . The method for producing an Ni-based alloy product according to  claim 1 ,
 wherein during the hot-forging step, the temperature of the hot-forging is lowered to a temperature by 100° C. or more below a hot-forging start temperature.   
     
     
         10 . The method for producing an Ni-based alloy product according to  claim 2 ,
 wherein during the hot-forging step, the temperature of the hot-forging is lowered to a temperature by 100° C. or more below a hot-forging start temperature.