United Technologies Corporation

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

Teledyne Industries, Inc.

John A Miller

Paul D Genereux

William J Gostic

Roy L Athey

Marvin Martin Allen

Daniel F Paulonis

John J Schirra

Jeffery W Samuelson

Laurence A Jackman

Ralph E Anderson, Jr

Fred P Cone

Timothy P Fuesting

Robert W Hatala

Robert Zanoni

Brendan J Cryns

William M Thomas

Frederick P Vaccaro

Bruce Edward Woodings

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 method of heat treating articles cast of a superalloy, comprising a nickel-base alloy capable of forming a chromium carbide precipitate, such as INCONEL 939.TM.. The method includes selective heating of the article to cause chromium and carbon nuclei in the lattice of the crystals in the superalloy to go into solution, and selective cooling of the article to cause the formation of discrete chromium carbide nuclei along the grain boundary of the crystals. Additional heating steps may be performed to enhance the size of the chromium carbide nuclei. Articles so treated have improved mechanical properties.

Method for producing crack-resistant high strength superalloy articles

A process for strengthening heavy, thick-section forgings of precipitation age hardenable iron base superalloys. The process includes initial recrystallization to achieve a uniform grain size, intermediate temperature warm working at controlled strain rates and for limited amounts of deformation, and precipitation heat treating. The controlled warm working conditions avoid further recrystallization, thus preserving the strain hardening which improves the mechanical properties.

Warm work processing for iron base alloy

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

A method is described for producing metallic articles, especially turbine disks, which have a hot-worked structure in one region and a warmworked structure in another region and thereby have properties which differ in different regions. The method comprises an initial hot-working step, an intermediate heat treatment step and a final warm-working step.

Method of producing turbine disks

An integrally bladed bimetallic rotor for high temperature operation having airfoils with good stress rupture and creep strength and a hub with high tensile strength and good low cycle fatigue resistance is made from a preform of two concentric cylinders of different superalloy metals metallurgically bonded to each other at their interface, both materials being in such a condition that they exhibit superplastic behavior at a certain, controlled strain rate and temperature without incurring substantial grain growth. The metal of the outer cylinder is selected such that it has a lower gamma prime solvus temperature than the metal of the inner cylinder. The preform is isothermally forged at the controlled strain rate and temperature to form the airfoils from the alloy of the outer cylinder and to form the hub from the alloy of the inner cylinder. A sharp, reproducible interface is created between the two alloys. After forging, the rotor is heated to a temperature between the gamma prime solvus temperatures of the alloys and under conditions which cause full gamma prime solutioning of the airfoils up to the interface but only partial gamma prime solutioning of the rotor hub. The resulting airfoils have coarse grains and the hub has fine equiaxed grains.

Process for fabricating integrally bladed bimetallic rotors

A thermomechanical treatment for producing useful microstructures in the nickel base superalloys is described. The process is applied to material which has been placed in a condition of super-plasticity, and utilizes isothermal hot deformation under conditions which produce a uniform dislocation density and a resultant propensity for abnormal grain growth. The material is then recrystallized in a thermal gradient to produce a final structure consisting of elongated grains.

Thermomechanical treatment for nickel base superalloys

Growing community of inventors

Jupiter, FL, United States of America

John A Miller