NiCrMoNb age hardenable alloy for creep-resistant high temperature applications, and methods of making

A method of homogenizing a nickel alloy comprising Cr and Nb, comprising at least two of the sequential steps of treating the nickel alloy:

• 1030=25° C. for 0.5 to 5 h;
• 1065±25° C. for 1.5 to 10 h;
• 1090±25° C. for 1.5 to 10 h;
• 1115±25° C. for 1.5 to 10 h;
• 1135±25° C. for 3 to 15 h;
• and
• 1150±25° C. for 30 to 150 h;
• wherein the nickel alloy is characterizable by a level of chemical homogeneity, defined as variations between local and nominal chemistry following homogenizing, of less than ±10%;
• and
• wherein the nickel alloy comprises 19.0 to 22.5% Cr;
• 0.1 to 1.0% Al;
• 1.0 to 2.0% Ti;
• 3.0 to 5.0% Nb;
• 0.1 to 4.0% Ta;
• 4.0 to 7.0% Nb+Ta;
• 2.0 to 4.0% Fe;
• 0 to 0.06% C;
• 0 to 0.35% Mn;
• 7.0 to 9.5% Mo;
• 0 to 5.0% W;
• 0 to 0.20% Si;
• 0 to 0.05% V;
• 0 to 0.15% P;
• 0 to 0.010% S;
• and 0 to 0.010% B, wherein all % are wt %, and comprising δ (and/or η) phase precipitates at the grain boundaries.

A method of heat treating a nickel alloy comprising Cr and Nb, comprising the sequential steps of treating the nickel alloy:

• 820±30° C. for 5 to 100 h, followed by cooling to 750±15° C. at a rate of 1 to 5° C./min, and then holding at 750±15° C. for 2 to 15 h;
• and
• wherein the nickel alloy comprises 17 to 25% Cr;
• 0.1 to 1.0% Al;
• 1.0 to 2.0% Ti;
• 3.0 to 5.0% Nb;
• 0.1 to 4.0% Ta;
• 4.0 to 7.0% Nb+Ta;
• and 2.0 to 4.0% Fe;
• greater than 50% Ni, wherein all % are wt %.