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

Rockwell International Corporation

Ohio State Innovation Foundation

Sheldon L Semiatin

Venkat K Seetharaman

Dennis M Dimiduk

Wei Zhang

Oleg N Senkov

Douglas R Barker

Paul A McQuay

David S Lee

David Mahaffey

Clarence R Thompson

Donald C Vollmer

Vinod K Jain

Sami M El Soudani

Carl A Lombard

Daniel Tung

Robert L Goetz

David P DeLo

Systems and methods for calculating efficiency of a rotary friction welding process are described herein. An example method can include measuring kinetic energy transferred from a welding machine to an interface of a welded joint, and calculating an efficiency of a rotary friction welding process based on the measured kinetic energy. For example, a workpiece torque experienced by a sample can be measured, and an energy associated with the workpiece torque can be calculated. The efficiency of the rotary friction welding process can then be calculated using the energy associated with the workpiece torque.

Systems and methods for determining efficiency of friction welding processes

A method is described for producing homogeneous wrought microstructure during equal channel angular extrusion of difficult-to-work high temperature alloys that exhibit a high degree of flow softening at hot-working temperatures, wherein flow non-uniformities are minimized by imparting an increment of initial upset deformation to an alloy immediately preceding shear flow through the deformation zone.

Equal channel angular extrusion of difficult-to-work alloys

A heat treatment and hot working method for producing a thin sheet of nickel base superalloy single crystals is described, wherein a single crystal preform of an alloy is first heat treated in vacuum at temperatures below the .gamma.' solvus temperature of the alloy in order to obtain an overaged .gamma.' microstructure in the preform, sized and surface ground in order to remove surface defects, and then preferably surrounded by plates and interlayers of refractory metal or alloy and parting agent coatings; the plates are then welded to form an enclosure and evacuated, preheated and soaked at 1093.degree. to 1150.degree. C. and rolled at roll speeds of about 0.12 to 0.25 rods in successive passes, at about 5 to 15% reduction per pass with reheating at the soaking temperature between successive passes, to a reduction in thickness of 50 to 75%; the plates are then removed and the preform is conditioned, repacked and successively rolled to preselected thickness.

Method for hot rolling single crystal nickel base superalloys

A heat treatment method for producing moderate .alpha. grain size (50-250 .mu.m) fully lamellar, microstructures in thin cross section near-.gamma. titanium aluminide alloy products is described, wherein a wrought, fine y grain starting microstructure is heated at a temperature high in the two-phase .alpha.+.gamma. phase field and 30-60.degree. C. below the .alpha. transus temperature to produce a structure of small equiaxed .alpha. grains (about 25 .mu.m dim) and fine .gamma. phase grains, which is then briefly heated to a temperature in the single-phase .alpha. field in order to complete dissolution of remnant .gamma. grains and to minimize growth of .alpha. grains. The material is then cooled to transform the microstructure to fully lamellar .alpha..sub.2 +.gamma..

Method for heat treating titanium aluminide alloys

A method for heat treatment of nonferrous metals and alloys is described which comprises the steps of providing a billet of material comprising nonferrous metal or alloy; rapidly heating the billet to a temperature higher than the transus or solvus temperature of the material whereby a microstructure of uniform single phase grains is formed in a surface layer of preselected depth or other selected region in the billet with the starting microstructure of the material central of the billet; and cooling the billet to room temperature to preserve in the billet surface the high temperature single phase microstructure or a transformation product thereof.

Rapid heat treatment of nonferrous metals and alloys to obtain graded

A method for thermomechanically processing gamma titanium aluminide alloy wrought products comprises the following steps: a) a near gamma titanium aluminide alloy ingot is cast; b) the ingot is hot isostatically pressed (HIP'ed) to seal off casting defects; c) the HIP'ed ingot is prepared into suitable forging preforms with or without intermediate homogenization heat treatment; d) the forging preforms are isothermally forged into suitable end product preforms at temperatures sufficiently close to the phase line between the alpha+gamma and alpha-two+gamma phase fields so as to break down the ingot microstructure and to yield a largely equiaxed gamma microstructure; and e) the end product preforms are processed into the desired wrought end products through a controlled rolling process or a closed-die forging operation.

Method for thermomechanical processing of ingot metallurgy near gamma

A method for extruding metals and alloys, particularly difficult-to-work high temperature alloys, is described which comprises inserting a billet of the metal or alloy into an extrusion can, heating the canned billet to a temperature in a temperature range in which the ductility of the billet material is substantially maximum, cooling the canned billet sufficiently to establish a preselected temperature difference between the billet and can at which the difference between the flow stress of the billet material and the flow stress of the can material is substantially minimum, and extruding the canned billet to preselected shape.

Controlled dwell extrusion of difficult-to-work alloys

A method for hot forging coarse grain materials to enhance hot workability and to refine microstructure is described which comprises the steps of imposing minimum initial deformation at low strain rate to effect initial dynamic recrystallization and grain refinement without fracture, and thereafter increasing the deformation rate to recrystallize the material and further refine grain structure. Depending on the deformation required to achieve full recrystallization at a given rate, deformation rate can be increased a number of times to further refine grain structure.

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Dayton, OH, United States of America

Sheldon L Semiatin