United Technologies Corporation

United States of America As Represented by the Secretary of the Air Force

William J Gostic

Charles M Biondo

John A Miller

Timothy P Fuesting

Paul D Genereux

Abdus S Khan

Chris C Rhemer

Roy L Athey

Scott E Hughes

Kenneth S Murphy

John C Tanzola

Christopher D Parmley

A repaired nickel-based superalloy substrate that has applied thereon a nickel-based polycrystalline repair alloy comprising 0.03-2.5 weight % hafnium, 0.003-0.32% boron, 0.02-0.16% yttrium and 0.007-0.35% zirconium. The present invention further provides a repaired single crystal alloy substrate that has applied thereon a repair alloy wherein the repair alloy's composition is similar to or the same as the single crystal alloy composition except that the repair alloy additionally comprises at least one grain boundary strengthener element and at least one element that enhances oxidation resistance.

Repaired nickel based superalloy

A process for producing a fine grain forged superalloy article having a high yield strength at intermediate temperatures. A preferred starting composition comprises, by weight, 15% Cr, 13.6% Co, 4.1% Mo, 4.6% Ti, 2.2% Al, 0.01% C, 0.007% B, 0.07% Zr, balance Ni. This material is forged at a temperature above the gamma prime solvus and at a true strain of at least 0.5. Alternately, the material may be forged below the gamma prime solvus temperature with intermediate super solvus anneals. The overaged material is then worked at a temperature below the gamma prime solvus. The resultant fine grain material is then heat treated or can be further isothermally forged prior to heat treatment to produce complex shapes.

Superalloy forging process

A cyclic heat treatment for eliminating the tendency of moderately deformed superalloys to recrystallize is described. The superalloys are subjected to a temperature cycle including a period at a high temperature and a period at a low temperature. The resultant heat treated articles are resistant to recrystallization at temperatures above the gamma prime solvus temperature.

Cyclic recovery heat treatment

Superalloy castings having large variations in section thickness are heat treated using a cyclic stress relief procedure, with the temperature being cycled between about 50.degree. F. (28.degree. C.) and 150.degree. F. (83.degree. C.) below the second phase particle solvus temperature, to relieve the residual stresses incurred during cooling within the mold following casting, followed by a solution cycle at a temperature about 25.degree. F. (14.degree. C.) below the second phase particle solvus temperature to dissolve some or all of the second phase particles.

Cyclic heat treatment for controlling grain size of superalloy castings

A thermomechanical method for fabricating net shape single crystal airfoils is disclosed. A cast single crystal superalloy workpiece is solution heat treated to provide a homogeneous gamma prime distrubition. The single crystal sheet stock is then warm worked, generally forged or rolled, at a working temperature of gamma prime solvus minus about 50.degree.-300.degree. F. with a maximum six percent deformation per pass. Following the first warm working, the single crystal sheet stock is cyclic annealed in a temperature range of gamma prime solvus minus about 50.degree.-125.degree. F. to prevent recrystallization of the single crystal sheet stock. The cyclic annealing is preferably cycled three to ten times between the low and high ends of the temperature range at a rate of change of temperature between about 1.degree. F. per minute to about 10.degree. F. per minute. The single crystal sheet stock is then again warm worked at the described temperatures and deformations, followed by another cyclic annealing step to prevent recrystallization. The alternating working and cyclic annealing steps are repeated until the sheet stock has achieved a desired final net shape of the airfoil.

Thermomechanical fabrication of net shape single crystal airfoils

Compositions and articles are described which have particular utility in gas turbine engine parts and which can be used at temperatures up to and in excess of 2,000.degree. F. without the usual protective coatings. Compositions are described which can be formed into single crystal articles which are alumina formers upon exposure to oxidation and in which develop an adherent spall resistant alumina scale during oxidation. The adherence and spall resistance of the alumina surface scale results from the presence of a small but critical quantity of zirconium.

Oxidation resistant superalloy single crystals

A process is described for the production of multiple single crystal articles having identical crystallographic orientations. A starting article is provided which consists of a single crystal portion and a fine grain portion. This starting article is bonded to another fine grain portion and the single crystal is caused to grow into the second article. The growth of the crystal is then stopped and the bonded article is severed to provide a single crystal article and another portion which can be used to repeat the process.

Growing community of inventors

Tequesta, FL, United States of America

William J Gostic