United Technologies Corporation

Edgar E Brown

Sherman M Snyder

Daniel F Paulonis

David R Malley

Michael P Smith

Duane L Ruckle

Martin J Blackburn

Robert W Hatala

A nickel base superalloy composition useful in the cast+HIP+heat treated condition is described. Articles having the invention composition have properties which are significantly better than similarly processed IN718 articles. This is achieved by modifying the chromium, columbium, and titanium contents in the alloy composition, relative to the IN718 composition.

High strength cast+HIP nickel base superalloy

Processing of Ti-6246 for improved mechanical properties including fracture toughness and low cycle fatigue. The process includes beta forging, sub beta transus solutionizing, controlled cooling and precipitation treating.

Method for improving fracture toughness of high strength titanium alloy

A nickel base superalloy composition useful in the cast+HIP+heat treated condition is described. Articles having the invention composition have properties which are comparable to similarly processed IN718 articles. The invention alloys have an as-cast microstructure which is substantially free from Laves phase, even at slow solidification rates. As a result, the alloys are significantly more weldable than IN718. This desirable microstructure is achieved by modifications of the chromium, molybdenum, iron, and nickel contents compared to the typical IN718 composition.

Laves free cast+hip nickel base superalloy

Heat treatments are described which improve subsequent HIP treatment results of superalloy articles. The heat treatments substantially eliminate certain low melting phases which otherwise would cause problems relating to gas entrapment during a HIP process. The articles are heated to a temperature near but below the intended HIP temperature for a period of time sufficient to reduce the low melting phase.

Pre-HIP heat treatment of superalloy castings

Forging processes are described for cast superalloys. The forgeability of superalloy materials is improved by the development of overaged microstructure. The total forging process is usually performed in a series of steps with intervening heat treatments to reform the overaged microstructure.

Forging process for superalloys

Disclosed is a nickel base alloy of the gamma-gamma prime type, the composition of which is controlled, to provide a gamma matrix phase in which solid solution hardener elements are minimized, to less than 12.5 weight percent. Preferably, the alloy consists essentially by weight percent of 0.25-9Al, 1-4Ti, 2-6Cb, 0.01-0.1C, at least one material selected from the group consisting by weight percent of 0-6Co, 0-6Mo, 2-7.5Cr, 0-2.5Hf and mixtures thereof, balance nickel. The gamma prime fraction in a heat treated article is in the range 10-45 volume percent. The stacking fault energy is preferably in the range 80-120 ergs/cm.sup.2. A gas turbine engine disc made of the material exhibits a three fold increase in fatigue life in the 550-750.degree. C. range, as compared to discs made of typical superalloys in current use, while retaining comparable tensile and stress rupture strength.

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South Windsor, CT, United States of America

Edgar E Brown