Low thermal expansion Ni-base superalloy
View Patent ↗The present invention relates to a low thermal expansion Ni-base superalloy containing, in terms of mass %, C: 0.15% or less; Si: 1% or less; Mn: 1% or less; Cr: 5% or more but less than 20%; at least one of Mo, W and Re, in which Mo+½(W+Re) is 5% or more but less than 20%; W: 10% or less; Al: 0.1 to 2.5%; Ti: 0.10 to 0.95%; Nb+½Ta: 1.5% or less; B: 0.001 to 0.02%; Zr: 0.001 to 0.2%; Fe: 4.0% or less; and a balance of inevitable impurities and Ni, in which the total amount of Al, Ti, Nb and Ta is 2.0 to 6.5% in terms of atomic %. The low thermal expansion Ni-base superalloy of the present invention has a thermal expansion coefficient almost equal to that of 12 Cr ferritic steel, excellent high temperature strength, excellent corrosion and oxidation resistance, good hot-workability, and excellent weldability.
1. A low thermal expansion Ni-base superalloy comprising, in terms of mass %,
C: 0.15% or less;
Si: 1% or less;
Mn: 1% or less;
Cr: 8.5% or more but less than 20%;
at least two of Mo, W and Re, in which Mo+½(W+Re) is 9.1% or more but up to 16.2%;
W: 10% or less;
Al: 0.98% to 1.85%;
Ti: 0.10 to 0.95%;
Nb+½Ta: 1.5% or less;
B: 0.001 to 0.02%;
Zr: 0.001 to 0.2%;
Fe: 4.0% or less; and
a balance of inevitable impurities and Ni,
wherein the total amount of Al, Ti, Nb and Ta is 2.0 to 6.5% in terms of atomic %.
2. The low thermal expansion Ni-base superalloy according to claim 1 , further comprising, in terms of mass %,
Co: 0.5% or more but less than 5.0%.
3. The low thermal expansion Ni-base superalloy according to claim 1 , wherein Mo+½(W+Re) is 9.1% or more but less than 10%.
4. The low thermal expansion Ni-base superalloy according to claim 2 , wherein Mo+½(W+Re) is 9.1% or more but less than 10%.