Treating nickel base alloys

Claim 1

A method of heat treating and coating a nickel base alloy consisting essentially of, by weight, from 12.0 to 20.0% chromium, from 4.0 to 7.0% titanium, from 1.2 to 3.5% aluminum, from 12.0 to 20.0% cobalt, from 2.0 to 4.0% molybdenum, from 0.5 to 2.5% tungsten, from 0.005 to 0.048% boron, from 0.005 to 0.15% carbon, up to 0.75% manganese, up to 0.5% silicon, up to 1.5% hafnium, up to 0.1% zirconium, up to 1.0% iron, up to 0.2% of rare earth elements that will not lower the incipient melting temperature below the solvus temperature of the gamma prime present in the alloy, up to 0.1% of elements from the group consisting of magnesium, calcium, strontium and barium, up to 6.0% of elements from the group consisting of rhenium and ruthenium, balance essentially nickel; said titanium plus said aluminum content being from 6.0 to 9.0%, said titanium and aluminum being present in a titanium to aluminum ratio of from 1.75:1 to 3.5:1, said heat treatment being a precipitation hardening heat treatment; said coating operation being incorporated within said heat treatment; said method comprising the steps of: heating said alloy at a temperature of at least 2050° F. to put most of the coarse gamma prime particles into solution; coating said alloy, said coating being a cobalt, nickel or iron base alloy; treating said coated alloy at a temperature of at least 1600° F. to lessen the sharp differential in chemistry between said coating and said alloy at the interface thereof; treating said alloy within the temperature range of between 1500° and 1800° F. to precipitate fine gamma prime particles, to coarsen existing gamma prime particles and to precipitate discrete carbide particles; cooling said alloy; and treating said alloy within the temperature range of between 1300° and 1500° F. to precipitate additional fine gamma prime particles, and discrete carbide particles at grain boundaries.

Claim 2

A method of heat treating and coating a nickel base alloy consisting essentially of, by weight, from 12.0 to 20.0% chromium, from 4.0 to 7.0% titanium, from 1.2 to 3.5% aluminum, from 12.0 to 20.0% cobalt, from 2.0 to 4.0% molybdenum, from 0.5 to 2.5% tungsten, from 0.005 to 0.048% boron, from 0.005 to 0.15% carbon, up to 0.75% manganese, up to 0.5% silicon, up to 1.5% hafnium, up to 0.1% zirconium, up to 1.0% iron, up to 0.2% of rare earth elements that will not lower the incipient melting temperature below the solvus temperature of the gamma prime present in the alloy, up to 0.1% of elements from the group consisting of magnesium, calcium, strontium and barium, up to 6.0% of elements from the group consisting of rhenium and ruthenium, balance essentially nickel; said titanium plus said aluminum content being from 6.0 to 9.0%, said titanium and aluminum being present in a titanium to aluminum ratio of from 1.75:1 to 3.5:1, said heat treatment being a precipitation hardening heat treatment; said coating operation being incorporated within said heat treatment; said method comprising the steps of: heating said alloy at a temperature of at least 2050° F. to put most of the coarse gamma prime particles into solution; coating said alloy, said coating being a cobalt, nickel or iron base alloy; treating said coated alloy at a temperature of at least 1600° F. to lessen the sharp differential in chemistry between said coating and said alloy at the interface thereof; treating said alloy within the temperature range of between 1500° and 1800° F. to precipitate fine gamma prime particles, to coarsen existing gamma prime particles and to precipitate discrete carbide particles; cooling said alloy; and treating said alloy within the temperature range of between 1300° and 1500° F. to precipitate additional fine gamma prime particles, and discrete carbide particles at grain boundaries.