Ni-based alloy, ni-based alloy for gas turbine combustor, member for gas turbine combustor, liner member, transition piece member, liner, and transition piece
A Ni-based alloy comprises nitrides, of which an estimated largest size is an area-equivalent diameter of 12 μm to 25 μm, the estimated largest size of the nitrides being determined by calculating an area-equivalent diameter D which is defined as D=A 1/2 in relation to an area A of a nitride with a largest size among nitrides present in a measurement field of view area S 0 of an observation of the Ni-based alloy, repeatedly performing this operation for n times corresponding to a measurement field of view number n to acquire n pieces of data of the area-equivalent diameter D, arranging the pieces of data of area-equivalent diameter D in ascending order into D 1 , D 2 , . . . D n to calculate a standardized variable y j , plotting the area-equivalent diameter D and the standardized variable y j on X and Y axes of an X-Y coordinate system, respectively, to obtain a regression line y j =a×D+b (wherein a and b are constants) to calculating y j where a cross-sectional area to be predicted S is 100 mm 2 , and substituting the obtained value of y j into the regression line to obtain the estimated largest size of the nitrides.
1. A Ni-based alloy having a composition comprising, by mass, 20.0% to 26.0% Cr, 4.7% to 9.4% Co, 5.0% to 16.0% Mo, 0.5% to 4.0% W, 0.3% to 1.5% Al, 0.1% to 1.0% Ti, 0.001% to 0.15% C, and at most 5% Fe and the balance of Ni with inevitable impurities,
wherein the Ni-based alloy comprises titanium nitrides, of which an estimated largest size is an area-equivalent diameter of 12 μm to 25 μm, the estimated largest size of the titanium nitrides being determined by calculating an area-equivalent diameter D which is defined as D=A 1/2 in relation to an area A of a titanium nitride with a largest size among titanium nitrides present in a measurement field of view area S 0 of an observation of the Ni-based alloy, repeatedly performing this operation for n times corresponding to a measurement field of view number n to acquire n pieces of data of the area-equivalent diameter D, arranging the pieces of data of area-equivalent diameter D in ascending order into D 1 , D 2 , . . . D n to calculate a standardized variable y j which is defined by the following expression:
y j =−ln [−ln { j /( n+ 1)}] [Expression 1]
wherein j denotes the number of the arranged ascending order of the data of the area-equivalent diameter D,
plotting the area-equivalent diameter D and the standardized variable y j on X and Y axes of an X-Y coordinate system, respectively, to obtain a regression line y j =a×D+b (wherein a and b are constants), calculating y j from the following expression:
y
j
=
-
ln
(
-
ln
S
S
0
+
S
)
[
Expression
2
]
where a cross-sectional area to be predicted S is 100 mm 2 , and substituting the obtained value of y j into the regression line to obtain the estimated largest size of the titanium nitrides wherein S 0 equals 0.306 mm 2 , n is greater than or equal to 30, and the observation of the Ni-based alloy is at an observation magnification of 400 to 1000 times or 1000 to 3000 times.
2. The Ni-based alloy according to claim 1 , wherein a scrap material is used as a raw material for the Ni-based alloy.
3. A Ni-based alloy for a gas turbine combustor, which is used for a gas turbine combustor, the Ni-based alloy consisting of the Ni-based alloy according to claim 1 .
4. A member for a gas turbine combustor, comprising the Ni-based alloy for gas turbine combustor according to claim 3 .
5. A liner member for a gas turbine combustor, comprising the Ni-based alloy for gas turbine combustor according to claim 3 .
6. A transition piece member for a gas turbine combustor, comprising the Ni-based alloy for gas turbine combustor according to claim 3 .
7. A liner of a gas turbine combustor, comprising the Ni-based alloy for gas turbine combustor according to claim 3 .
8. A transition piece of a gas turbine combustor, comprising the Ni-based alloy for gas turbine combustor according to claim 3 .
9. A hot-rolled plate comprising the Ni-based alloy according to claim 1 , wherein a content of Fe is 0.01% to 5% by mass.