Fatigue crack growth resistant nickel-base article and alloy and method for making
AssigneeGeneral Electric Company
InventorsDaniel D. Krueger, Robert D. Kissinger, Richard G. Menzies, Carl S. Wukusick
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Abstract
An article having improved fatigue crack growth resistance is provided through an improved nickel-base superalloy and an improved method which controls grain size and a strain rate found to be critical in processing. The alloy is selected to have a gamma prime content in the range of about 30-46 volume percent and a resistance to cracking upon rapid quenching from a selected supersolvus solutioning temperature to a selected quenching temperature. The article produced has an improved balance and combination of fatigue crack growth resistance and tensile, creep, and stress rupture properties.
Claims20
In a method of making an article from a gamma prime precipitation strengthened nickel-base superalloy having a gamma prime solvus temperature and an incipient melting temperature, the steps of:
- providing a nickel-base superalloy (a) which includes a gamma prime content in the range of about 30-46 volume percent, and (b) which has a quench crack resistance to enable rapid quenching substantially without cracking from a preselected supersolvus solutioning temperature, above the gamma prime solvus temperature and below the incipient melting temperature, to a preselected quenching temperature;
- working the superalloy at preselected working conditions, including a working temperature below the gamma prime solvus, at a strain rate less than a predetermined critical strain rate, E.sub.c, to provide a worked structure having a grain size substantially no larger than about ASTM 10, a precipitate of gamma prime, and a high temperature carbide precipitate comprising MC carbide;
- heating the worked structure at the supersolvus solutioning temperature for a time sufficient to solutionize substantially all of the gamma prime but not the MC carbide, and to coarsen grains uniformly to a range of about ASTM 2-9;
- and
- quenching the structure rapidly to the quenching temperature to reprecipitate gamma prime without substantial cracking of the structure.
A high strength, fatigue crack growth and creep resistant nickel base superalloy article in which:
- the superalloy consists, in weight percent, essentially of 12-14Co, 15-17Cr, 3.5-4.5Mo, 3.5-4.5W, 1.5-2.5Al, 3.2-4.2Ti, 0.5-1Nb, 0.01-0.04B, 0.01-0.06C, 0.01-0.06Zr, up to about 0.01V, up to about 0.3Hf, up to about 0.01Y, with the balance essentially Ni and incidental impurities;
- the superalloy has a gamma prime content in the range of about 30-46 volume percent;
- the average grain size is in the range of about ASTM 2-9;
- the article is substantially free of quench cracking;
- and
- the article has an improved balance and combination of average tensile, creep, stress rupture and fatigue crack growth resistance from ambient up to a temperature of about 1400.degree. F.
An improved Ni-base superalloy for use in making a high strength fatigue crack growth and creep resistant article for application from ambient up to a temperature of about 1400.degree. F.:
- consisting essentially of, in weight percent, 12-14Co, 15-17Cr, 3.5-4.5Mo, 3.5-4.5W, 1.5-2.5Al, 3.2-4.2Ti, 0.5-1Nb, 0.01-0.04B, 0.01-0.06C, 0.01-0.06Zr, up to about 0.01V, up to 0.3Hf, up to 0.01Y, with the balance essentially Ni and incidental impurities;
- the superalloy including a gamma prime content in the range of about 33 to 46 volume percent;
- the superalloy having uniformly coarsened grains to an average grain size of about ASTM 2-9 with a substantial absence of critical grain growth;
- the superalloy having substantial quench crack resistance from a supersolvus solutioning temperature to a preselected quenching temperature;
- and
- the superalloy having a strain rate sensitivity, m, of at least 0.3 at preselected superalloy working conditions.
Dependencies are inferred from the claim text.