Ni-based super heat-resistant alloy and method for manufacturing same

Abstract

Ni-based super heat-resistant alloys have a composition in which the equilibrium precipitated amount of a gamma prime phase at 700° C. is 35 mol % or greater, and have grains having a maximum diameter of 75 nm or less in cross-sectional structure. One Ni-based super heat-resistant alloy manufacturing method includes preparing a raw material of a Ni-based super heat-resistant alloy having the aforementioned composition, and performing plastic processing of the raw material a plurality of times at a temperature of 500° C. or less so as to obtain a cumulative processing rate of 30% or greater. Another Ni-based super heat-resistant alloy manufacturing method includes preparing an alloy material having the aforementioned composition, a hardness of 500 HV or greater, and the aforementioned crystal grain maximum diameter, performing plastic processing of the alloy material at a temperature of 500° C. or less, and obtaining an alloy having a hardness of 500 HV or greater.

1 . A super heat resistant Ni-based alloy having a composition such that an amount of precipitated gamma prime phase in equilibrium at 700° C. is not less than 35 mol %, and having a cross-sectional structure including grains having a maximum grain size of not more than 75 nm. 
     
     
         2 . The Ni-based alloy according to  claim 1 , having a hardness of not less than 500 HV. 
     
     
         3 . The Ni-based alloy according to  claim 1 , wherein the cross-sectional structure includes not less than 5 grains having a maximum grain size of not more than 75 nm per 1 μm 2 . 
     
     
         4 . The Ni-based alloy according to  claim 1 , comprising, by mass %,
 0 to 0.25% of C,   8.0 to 25.0% of Cr,   0.5 to 8.0% of Al,   0.4 to 7.0% of Ti,   0 to 28.0% of Co,   0 to 8% of Mo,   0 to 6.0% of W,   0 to 4.0% of Nb,   0 to 3.0% of Ta,   0 to 10.0% of Fe,   0 to 1.2% of V,   0 to 1.0% of Hf,   0 to 0.300% of B,   0 to 0.300% of Zr, and   the balance of Ni and impurities.   
     
     
         5 . The Ni-based alloy according to  claim 1 , having a composition such that an amount of precipitated gamma prime phase in equilibrium at 700° C. is not less than 40 mol %. 
     
     
         6 . The Ni-based alloy according to  claim 1 , comprising, by mass %,
 0 to 0.03% of C,   8.0 to 22.0% of Cr,   2.0 to 8.0% of Al,   0.4 to 7.0% of Ti,   0 to 28.0% of Co,   2.0 to 7.0% of Mo,   0 to 6.0% of W,   0 to 4.0% of Nb,   0 to 3.0% of Ta,   0 to 10.0% of Fe,   0 to 1.2% of V,   0 to 1.0% of Hf,   0 to 0.300% of B,   0 to 0.300% of Zr, and   the balance of Ni and impurities.   
     
     
         7 . A method of manufacturing the super heat resistant Ni-based alloy according to  claim 1 , comprising:
 a preparation step of preparing a raw material of the Ni-based alloy having the composition; and   a working step of plastically working the raw material multiple times at a temperature of not higher than 500° C. so that a cumulative working rate is not less than 30%.   
     
     
         8 . The method according to  claim 7 ,
 wherein the raw material has a form of a bar material, and   wherein the plastic working reduces a cross-sectional area of the bar material.   
     
     
         9 . The method according to  claim 8 , wherein the plastic working includes a step of compressing the bar material from a peripheral surface toward an axis of the bar material. 
     
     
         10 . The method according to  claim 7 , wherein no heat treatment is performed between the times of the plastic working. 
     
     
         11 . A method of manufacturing a super heat resistant Ni-based alloy having a composition such that an amount of precipitated gamma prime phase in equilibrium at 700° C. is not less than 35 mol %, the method comprising:
 a preparation step of preparing an alloy material, the material having a hardness of not less than 500 HV and having a cross-sectional structure including grains having a maximum grain size of not more than 75 nm; and 
 a working step of plastically working the alloy material at a temperature of not higher than 500° C., thereby producing an alloy having a hardness of not less than 500 HV. 
 
     
     
         12 . The method according to  claim 11 , wherein the working step is repeated multiple times. 
     
     
         13 . The method according to  claim 12 , wherein no heat treatment is performed between the working steps. 
     
     
         14 . The method according to  claim 11 , wherein the alloy material and the alloy have a cross-sectional structure including not less than 5 grains having a maximum grain size of not more than 75 nm per 1 μm 2 . 
     
     
         15 . The method according to  claim 11 , wherein the Ni-based alloy comprises, by mass %,
 0 to 0.25% of C,   8.0 to 25.0% of Cr,   0.5 to 8.0% of Al,   0.4 to 7.0% of Ti,   0 to 28.0% of Co,   0 to 8% of Mo,   0 to 6.0% of W,   0 to 4.0% of Nb,   0 to 3.0% of Ta,   0 to 10.0% of Fe,   0 to 1.2% of V,   0 to 1.0% of Hf,   0 to 0.300% of B,   0 to 0.300% of Zr, and   the balance of Ni and impurities.   
     
     
         16 . The method according to  claim 11 , wherein the Ni-based alloy has a composition such that an amount of precipitated gamma prime phase in equilibrium at 700° C. is not less than 40 mol %. 
     
     
         17 . The method according to  claim 11 , wherein the Ni-based alloy comprises, by mass %,
 0 to 0.03% of C,   8.0 to 22.0% of Cr,   2.0 to 8.0% of Al,   0.4 to 7.0% of Ti,   0 to 28.0% of Co,   2.0 to 7.0% of Mo,   0 to 6.0% of W,   0 to 4.0% of Nb,   0 to 3.0% of Ta,   0 to 10.0% of Fe,   not more than 1.2% of V,   0 to 1.0% of Hf,   0 to 0.300% of B,   0 to 0.300% of Zr, and   the balance of Ni and impurities.   
     
     
         18 . The Ni-based alloy according to  claim 1 , having a composition such that an amount of precipitated gamma prime phase in equilibrium at 700° C. is not less than 50 mol %. 
     
     
         19 . The Ni-based alloy according to  claim 1 , wherein the Ni-based alloy is in a form of a wire having a diameter of not more than 10 mm, in a form of a sheet having a thickness of not more than 10 mm, or in a form of a strip having a thickness of not more than 10 mm. 
     
     
         20 . The Ni-based alloy according to  claim 1 , wherein the Ni-based alloy is in a form of a wire having a diameter of not more than 5 mm, in a form of a sheet having a thickness of not more than 5 mm, or in a form of a strip having a thickness of not more than 5 mm. 
     
     
         21 . The method according to  claim 7 , wherein the Ni-based alloy has a hardness of not less than 500 HV. 
     
     
         22 . The method according to  claim 11 , wherein the Ni-based alloy has a composition such that an amount of precipitated gamma prime phase in equilibrium at 700° C. is not less than 50 mol %