Ni-based alloy having excellent hydrogen embrittlement resistance, and method for producing ni-based alloy material

Abstract

An object is to provide a Ni-based alloy having high strength and excellent hydrogen embrittlement resistance even in a high-temperature and high-pressure environment and particularly capable of being used for an ammonothermal pressure vessel and the like. The present invention relates to a Ni-based alloy including, in terms of mass ratios, Fe: 30 to 40%, Cr: 14 to 16%, Ti: 1.2 to 1.7%, Al: 1.1 to 1.5%, Nb: 1.9 to 2.7%, and P: 40 to 150 ppm, with the remainder being Ni and unavoidable impurities.

1 . A Ni-based alloy comprising, in terms of mass ratios, Fe: 30 to 40%, Cr: 14 to 16%, Ti: 1.2 to 1.7%, Al: 1.1 to 1.5%, Nb: 1.9 to 2.7%, and P: 40 to 150 ppm, with the remainder being Ni and unavoidable impurities. 
     
     
         2 . The Ni-based alloy according to  claim 1 , which further comprises at least either one of Mg: 0.01% or less and Zr: 0.1% or less in terms of mass ratios. 
     
     
         3 . The Ni-based alloy according to  claim 1 , wherein a hydrogen embrittlement index EI defined by EI=(RA A −RA H )/RA A  when a reduction of area of a hydrogen charged material and a reduction of area of a hydrogen non-charged material at a tensile test are indicated as RA H  and RA A , respectively, is 0.1 or less at 625° C. 
     
     
         4 . The Ni-based alloy according to  claim 1 , wherein a creep rupture time at 700° C. and 333 MPa is 1,500 hours or more. 
     
     
         5 . The Ni-based alloy according to  claim 1 , wherein a minimum creep rate at 700° C. and 333 MPa is 1×10 −8  s −1  or less. 
     
     
         6 . The Ni-based alloy according to  claim 1 , which is used as an ammonothermal pressure vessel material. 
     
     
         7 . A method for producing a Ni-based alloy material, said method comprising subjecting the Ni-based alloy according to  claim 1  to a solution treatment and subsequently to an aging treatment twice at a temperature of 825 to 855° C. and at a temperature of 710 to 740° C.