United Technologies Corporation

Earle A Ault

Thomas T Field

Richard W Salkeld

Donald R Parille

Charles E Bevan

Thomas A Murrin

A ceramic core is removed from an investment casting by directing a stream of high pressure alkali solution between about 5,000 psi (345 bar) and about 10.000 psi (690 bar) at the core to loosen and dissolve the core.

Method of core leach

Unwanted recrystallization during heat treatment of a directionally solidified nickel alloy single crystal casting is prevented by chemical milling the part before heat treatment. Removal of a layer of as little as 0.013-0.050 mm thick, less than two percent of the part thickness, has been found effective.

Preparation of single crystal superalloys for post-casting heat treatment

Methods for heat treating cast, nickel base superalloy articles are described. According to the invention, the articles are heated to progressively higher temperatures greater than the gamma prime solvus temperature and less than the incipient melting temperature. The incipient melting temperature is increased due to homogenization of segregate phases, while at the same time, the gamma prime goes into solution. The rate at which the temperature is increased closely approximates the rate at which the incipient melting temperature increases due to homogenization.

Varied heating rate solution heat treatment for superalloy castings

A heat treatment is described for producing a desired microstructure in Hastelloy Alloy X components which have small diameter, closely spaced, laser pierced holes therein. The heat treatment produces a small grain size and discontinuous carbide morphology in the component prior to the hole piercing operation, which reduces the propensity for cracking which has been found to be associated with the hole piercing operation. After the piercing operation, the component is heat treated again to increase the grain size and produce a microstructure which provides the optimum balance of creep strength and fatigue strength.

Thermal treatment of wrought, nickel base superalloys in conjunction

Residues accumulated during use are removed from the small interior cavities of superalloy airfoils by a process which includes exposing the interior of the part to an aqueous solution of 20-45% potassium hydroxide at a pressure of 10.4-24 kPa (150-350 psi) and temperature of 150.degree.-235.degree. C. (300.degree.-450.degree. F.) for about 20 hours, followed by water blasting using a pressure greater than about 14 MPa (2,000 psi). Unless the part is kept continuously wet between the first and second steps, the second step will not be effective.

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South Windsor, CT, United States of America

Earle A Ault