Showing papers on "Forging published in 1987"

Process for the densification of material preforms.

Abstract: A process for preparing dense, consolidated bodies, the process comprising compressing in a forging press an isostatic die assembly, the assembly comprising a preform surrounded by a fluid pressure-transmitting medium, the medium and the preform being contained in a shell having an open top; under sufficient conditions of temperature, time and pressure that a dense, consolidated body of desired shape is formed, and then recovering the body by separating the body from the fluid pressure-transmitting medium.

Nickel base superalloy articles and method for making

Abstract: A process is described for converting a fine grain superalloy casting into a forging having mechanical properties equivalent to those resulting from powder metallurgy processing. Cast material is extruded and forged. A HIP treatment is employed to close porosity.

Finite element calculation of three‐dimensional hot forging

Abstract: A three-dimensional finite, element model for the simulation of isothermal hot forging is presented. The material behaviour is assumed to be incompressible visco-plastic (Norton–Hoff law), with the associated friction law. The velocity field is calculated with a finite element approximation using eight node hexahedral or six node prismatic elements. An explicit Euler scheme is used for time integration. Simulations of compression of a cubic block and horizontal cylinder are performed. The computed results are compared with experimental measurements made on special Plasticine.

Enhancement of Strength through Sinter Forging

Abstract: Packing defects in powder compacts can develop into microcracks during the sintering process. For example, an agglomerate which sinters differently than its surroundings can open up large, cracklike defects which are difficult to remove in free sintering. Traditionally, hot-pressing or hot isostatic pressing has been used to prevent the formation of such defects. Here we show that processing defects can be virtually eliminated by sinter forging. In sinter forging the powder preform is compacted under a uniaxial compressive stress without any lateral constraint. In this way both densification and shear strain are imposed on the specimen. We have found that the shear strain can eliminate large pores by changing their shape. Eventually the flattening of the pore under compressive strain causes it to disintegrate into small pores which are then removed by sintering, leading to an increase in the strength of the ceramic. In alumina, a sigmoidal curve for the change in strength with strain is obtained where the strength begins to increase at 20% shear strain and reaches a maximum value at 60% strain. The shear strain required for the improvement in strength is compared with theoretical estimates.

Process for improving the static and dynamic mechanical properties of (alpha + beta) titanium alloys

Abstract: The process relates to the improvement of the static and dynamic mechanical properties of (α+β) titanium alloys by thermomechani­cal treatment, wherein the alloys produced by melting and forging and/or hot isostatic pressing of powders are deformed by more than 60 % with simultaneous strain-hardening at a temperature just above the recrystallization temperature of the relevant alloys in one or more steps, with structure stress-relief heatings being performed without complete recrystallization between these individual steps, the shaped part is then tempered for 2 to 4 min near the transus of the alloy, quenched and then aged at temperatures in the range of from 400 to 600°C.

The Spray Forming of Superalloys

Abstract: Spray forming involves the gas atomization of a stream of molten metal to form droplets, and depositing the droplets on a collector before they have solidified. By manipulating the stream and/or the collector, a variety of useful shapes such as disks, bars, sheet, and plate can be made. As a consequence of rapid solidification, the product is homogeneous and is comprised of small, equiaxed grains, making it well suited to further processing. Discussed are the spray forming of 718 and Rene 95, and the properties after heat treatment, both as-deposited and after forging. Also reviewed are recent developments with respect to the processing of a range of near-net shape products.

Modeling and solving the flexible forging module scheduling problem

Abstract: In this paper, an existing small scale manufacturing system called a Flexible Forging Module (FFM) is considered. For this system the sequence-dependent changeover costs have been identified. In order to obtain an optimal schedule, a network model is developed which easily incorporates both the sequence-dependent changeover costs and the precedence constraints. A branch and bound algorithm is outlined and numerical results are reported.

Method of making heat resistant heavy-duty components of a turbine by superplasticity forging wherein different alloys are junctioned

Abstract: The method concerns fabricating heat-resistant heavy-duty components of a rbine, e.g. disk, wheel, etc. wherein two or more different kinds of alloys are junctioned, which comprises solidifying the one alloy powder by hot isostatic pressing or extrusion, junctioning and solidifying the solidified alloy with the other alloy powder by hot isostatic pressing or extrusion, and subjecting the alloys thus obtained to superplasticity forging thereby to secure the junction boundary. Ni-base superalloys having different complete solid solution temperatures of gamma prime phase are selected for use in the hub and rim of a turbine disk or the like, the one alloy which is higher in the temperature being disposed for the hub and the other alloy for the rim. The difference in the temperature between both alloys is at least 8° C. Further solution heat treatment is performed at a temperature between the complete solid solution temperatures to adjust crystal grain size. Heat-resistant heavy-duty components of a turbine, e.g. disk, etc. are thus fabricated by superplasticity forging from Ni-base superalloys.

Process for upset forging of long stands of metal bar stock

Abstract: Process and apparatus for upset forging a long stand of solid malleable metal bar stock in a single pass is capable of gathering a large volume of the bar stock into a complex shaped element. The end of the bar stock is selectively heated to provide an intermediate section thereof to a desired upper forging temperature and an end section thereof at a desired lower forging temperature. The heated bar stock is positioned in an upset forging die cavity. A forging punch enters the cavity to upset the long stand to fill the cavity firstly with the upset intermediate section and then the remainder of the cavity with the end section which is at a lower forging temperature. A friction reducing material is provided in the cavity to provide for sliding of the end section along the cavity while the end seciton upsets and gathers the intermediate section of the bar in the major portion of the upset cavity section.

Die design alternatives for precision forginghollow parts

Abstract: In this paper eighteen die design alternatives for precision forming hollow parts are examined in respect to the form and kinematics of die elements, ease of die filling, accommodation space for excess billet material, ejection, forging load and die life. Forging tests on some designs confirm their predicted performance.

Magnetization of sinter‐forged YBa2Cu3O7−δ

Abstract: The magnetization and critical magnetization current densities of sinter‐forged YBa2Cu3O7−δ samples of nearly theoretical density have been studied. The magnetization curves can be well fitted by Kim’s critical state equation Jc(B)=α/(B0+B) with a flat plate geometry. The results revealed an anisotropy in the lower critical field and the critical current density with respect to the forging axis. The deduced critical current density in the favorable direction is larger than the value of isotropic polycrystalline samples.

Manufacture of heat resistant ti-al alloy

Abstract: PURPOSE: To enhance the strength of an intermetallic compd. Ti-Al alloy having a specified compsn. and to improve the ductility and toughness, by subjecting the alloy to isothermal forging, annealing and isothermal forging in one ore more steps. CONSTITUTION: An intermetallic compd. Ti-Al alloy consisting of 30W40% Al and the balance Ti with inevitable impurities is isothermally forged at ≥800°C to destroy the coarse structure and to form a fine uniform structure. The forged alloy is annealed at ≥800°C to make the structure isometric and homogeneous. The annealed alloy is isothermally forged again in one or more steps at 700W1,100°C and ≥10% working rate. The structure is made finer by the forging to enhance the strength. The resulting alloy has satisfactory hot workability and can be used as the material of engine members for an airplane and an automobile. COPYRIGHT: (C)1988,JPO&Japio

Method for improving fracture toughness of high strength titanium alloy

Abstract: 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.

Ring forging process

Abstract: A process is described for producing forged ring articles from high strength, high temperature materials such as superalloys and titanium alloys. The material to be forged is conditioned and placed into a condition of low strength and high ductility. This starting material is then back extruded to produce a cup. The cup can be sliced into rings in which can thereafter be final forged to a particular contour.

Process for improving the static and dynamic mechanical properties of (α+β)-titanium alloys

Abstract: The process relates to the improvement of the static and dynamic mechanicalroperties of (α+β) titanium alloys by thermomechanical treatment, wherein the alloys produced by melting and forging and/or hot isostatic pressing of powders are deformed by more than 60% with simultaneous strain-hardening at a temperature just above the recrystallization temperature of the relevant alloys in one or more steps, with structure stress-relief heatings being performed without complete recrystallization between these individual steps, the shaped part is then tempered for 2 to 4 min near the transus of the alloy, quenched and then aged at temperatures in the range of from 400° to 600° C.

Tensile and strain-controlled fatigue data for certain aluminum alloys for application in the transportation industry

Abstract: Monotonic and cyclic strain-controlled fatigue tests were conducted at room temperature on several heat-treatable and non-heat-treatable aluminum alloys of interest to the transportation industry. Extrusion, forging, plate, and sheet product-forms were tested. Various monotonic and cyclic fatigue properties are furnished, and the respective strain-life curves are compared. In general, materials with strong monotonic strain-hardening tendencies are also shown to exhibit marked cyclic hardening.

Method for producing a precipitation hardenable martensitic low alloy steel forging

Abstract: A precipitation-hardenable martensitic low alloy steel for use in producing forgings having an improved combination of strength and toughness. The steel may be quenched directly from forging temperature. The composition of the steel consists essentially of, in weight percent, less than 0.20 carbon, 1.0 to 2.5 manganese, 0.10 to 1.5 silicon, 0.01 to less than 1.0 of at least one carbide, nitride or carbonitride forming element which may be niobium, titanium, vandium aluminum, zirconium or tantalum, less than 0.05 nitrogen, 0.01 to less than 2.0 of at least one of molybdenum, nickel and chromium and the balance iron. The steel upon quenching directly from forging temperature has a yield strength of 90,000 to 165,000 psi, a tensile strength of 120,000 to 210,000 psi, impact energy greater than 15 foot pounds at -22° F. and a ductile-to-brittle transition temperature between minus 40° F. and -25° F.

Manufacture of high strength stainless steel bolt

Abstract: PURPOSE: To manufacture the bolt equipped with a corrosion resistance and high strength by forging after cold working the stainless steel consisting of the specified alloy component in the specified concentration and sufficiently adjusted so that the relation of the cold working amt. at the times of stock manufacture and bolt forming may satisfy an equation I. CONSTITUTION: The wire rod or bar stock consisting of the stainless steel contg. C, Si, Mn, P, S, Cu, Ni, Cr, N, A, Mg and Ca in the specified concentration respectively, contg. at least one kind of V, Ti, Nb+Ta in the specified concentration, and the balance Fe and sufficiently adjusted so that the relation of the cold working amt. at the times of a stock manufacture and bolt forming may satisfy an inequality I is obtd. This wire rod or bar stock is subjected to a solid solution treatment, a cold working is executed and it is cut in a fixed dimension. This material is transferred to a rolling part, subjected to forging by a punch 11, die 21, etc., and the bolt stock having the specified head shape is made. A nonmagnetic high strength bolt excellent in corrosion resistance can thus be manufactured. COPYRIGHT: (C)1989,JPO&Japio

Method of forging dual alloy billets

Abstract: An improved forging billet of dual alloys and an improved method for forging a dual alloy billet. The billet is cylindrical in shape having an outer tubular portion of one alloy and another alloy filling the central opening through the tubular portion, the ends of the billet include a radial flange of the tubular alloy extending a short distance outward at each end of the billet and having a skirt extending from the outer end of the radial flange axially away from the body of the billet to form a circular opening at each end of the billet which has at least as large a diameter as the outer diameter of the outer tubular portion, and a sandwich structure positioned within each of said circular opening including a plurality of layers of a powdered lubricant, preferably boron nitride lubricant, separated by foil layers, preferably a high purity nickel foil. The method includes the step of forging a dual alloy billet as described above into a disc having an interface between the two alloys which is substantially straight and generally parallel to the axis of the disc. The steps of the improved method include positioning the billet between the dies, providing lubrication with the billet to be sufficient to lubricate between the die surfaces and the billet to produce the desired dual alloy disc and forging the billet by moving the dies toward each other sufficiently to produce the desired forged product.

Die Wall Lubrication for Powder Compaction: A Feasible Solution?

Abstract: The development of an automatic die wall lubrication system for use during powder compaction of ferrous based materials is described. The technique, employing EP oil fed to the die wall interface under slight air pressure and augmented by the action of the toolset, appears to work very well. Following comprehensive laboratory scale development of the technique, involving particularly lubricant selection, satisfactory works trials have been implemented. Five thousand simple preforms for subsequent powder forging and 2000 green compacts for a commercial sintered component of some geometric complexity have been produced in a modified production toolset. PM/0450

Production of bevel gear

Abstract: PURPOSE: To improve the mass productivity and accuracy of a product by forming a tooth profile part by its forging from a heated blank, then executing warm sizing in forged preheating state and after nonoxidizing normalizing and shot stages executing cold sizing. CONSTITUTION: A beveling part is formed with cold forging 5 on the blank 4a subjected to bonderiging in advance and heated at the specified temp. to execute warm side forging 7. Piercing and sizing 8 are then executed simultaneously at warm temp. with the remaining heat state of 600W850°C on the bevel gear 7a forming a tooth profile part 7b. And after executing a nonoxidizing normalizing 9 and shot 10 on a bevel gear 8a a product gear 11a is formed with cold sizing 11. Since the cold sizing 1 is executed once again after the warm sizing 7 the forming is reasonably executed. The mass productivity and accuracy of a produce are therefore improved. COPYRIGHT: (C)1988,JPO&Japio

Bearings fabricated from rapidly solidified powder and method

Abstract: A process of fabricating steel stock for bearing components from highly alloyed steel powders supersaturated in carbon up to 0.5 weight percent in ferrite and up to 1.0 weight percent in austenite type combinations is disclosed. Rapid solidification of an atomized molten composition yields a metal powder with a diameter ranging between 75 and 105 microns. The metal powder is then compressed and heated to a low forging temperature between 1,600° and 1,800° F. to yield the steel stock.