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AssigneeUnited Technologies Corporation
InventorsThomas D. Tillman, John M. Robertson, Arthur R. Cox
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Nickel base superalloy articles, especially gas turbine disks, are provided with substantially enhanced resistance to crack growth through a specific heat treatment. The heat treatment employs a true solution treatment step followed by a subsolvus solution treatment step, followed by at least one aging step. The effect of this series of heat treatment steps is to provide a microstructure having an optimum arrangement of gamma prime particles, with respect to both size and location. Reductions in crack growth rates of several hundred percent relative to prior art heat treatments are achieved.
A heat treatment for reducing the crack growth rate in superalloy articles which consist essentially of 12-15.5% chromium, 8-19% cobalt, 2-4.5% titanium, 3.2-5.2% aluminum, 2.8-5.4% molybdenum, 0.01-0.1% carbon, 0-0.08% zirconium, 0.005-0.024% boron, 0-1% vanadium, 0-4% tantalum, 0-1.5% columbium, 0-0.45% hafnium, 0-4% tungsten, balance nickel, which consists of:
A heat treated superalloy article consisting essentially of 12.4% chromium, 18.5% cobalt, 4.3% titanium, 5.0% aluminum, 3.2% molybdenum, 0.07% carbon, 0.8% vanadium, 0.06% zirconium, 0.02% boron, balance nickel, having a grain size of 20-90 microns, and containing a triplex distribution of gamma prime particles with about 6% by volume having a size of about 2-4 microns, about 40% by volume having a size of about 0.7-0.9 microns and about 54% by volume having a size of less than about 0.2 micron.
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