HIGH-TEMPERATURE FATIGUE-RESISTANT NICKEL BASED SUPERALLOY AND THERMOMECHANICAL PROCESS

Abstract

A nickel based superalloy composition is disclosed that provides increased high temperature stress-rupture strength and improved resistance to fatigue crack propagation at elevated temperatures up to about 760 DEG C. The composition is comprised of, by weight percent, about 10% to 12% chromium, about 17% to 19% cobalt, about 1.5% to 3.5% molybdenum, about 4.5% to 6.5% tungsten, about 3.25% to 4.25% aluminum, about 3.25% to 4.25% titanium, about 2.5% to 3,5% tantalum, about 0.02% to 0.08% zirconium, about 0.005% to 0.03% boron, less than 0.1% carbon, and the balance essentially nickel. Thermomechanical processing including isothermal forging at controlled strain rates and temperature ranges, supersolvus annealing, and slow cooling are disclosed for producing an enlarged grain structure that provides the improved properties in the alloy of this invention.

Source: Google Patents

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Inventor

• 1KEH-MINN CHANG