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Session Chairperson: Dr. D.J. Chellman, Lockheed Martin Aeronautical Systems, Marietta, GA 30063
8:30 am KEYNOTE
THE COMMERCIAL SCALE APPLICATION OF SPRAY FORMED MATERIALS: A.J.W. Ogilvy, A.C. Lealham, Osprey Metals Ltd., UK
Advanced materials produced by the Osprey Process are satisfying an ever wider range of applications. The driving force for process substitution may be either cost, property improvement or novel materials which are unobtainable using any other production route. This paper will discuss examples of spray-formed materials in the aerospace, automotive, metal processing and electronic industries. In each case, the reasons for the successful commercial application of the materials will be discussed. In addition, details of the requirements for large-scale production of spray-formed alloys and process developments to reduce costs and improve product reproducibility will be given. Post processing of the as-sprayed products to satisfy customer requirements will also be covered.
NAVY RESEARCH AND DEVELOPMENT IN METAL SPRAY FORMING: Richard Rebis, Materials Engineer, Naval Surface Warfare Center, Carderock Division (NSWC-CD), Code 6120, Bethesda, MD 20084-5000; Craig Madden, Director, Manufacturing Programs, NSWC-CD, Code 7206, Bethesda, MD 20084-5000; Patricia Mahoney, Mechanical Engineer, NSWC-CD, Code 7220, Bethesda, MD 20084-5000
The Metal Spray Forming Technology Group of the Naval Surface Warfare Center, Carderock Division (NSWC-CD) has conducted research in support of Navy and private industry programs. In the spray forming process, a liquid stream of molten metal is atomized into a spray of semi-solid, semi-liquid particles and the metal spray is subsequently collected onto either a cylindrical or flat substrate that is rotating and translating underneath the spray. Spray forming produces a characteristic fine equiaxed, nearly-full dense microstructure in a near net shape product which can be subsequently processed. NSWC-CD has both non-reactive and reactive metal (titanium) R&D spray forming facilities. The non-reactive facility has a 300 lb. Melt capacity and is used to produce nickel, steel, or copper alloy parts. Over 380 runs have been conducted on this R&D plant since 1988. This facility is also used to produce prototype parts in support of the Navy Manufacturing Technology spray forming plant, which is currently operated by Babcock & Wilcox. In 1995, NSWC-CD installed a Reactive (Titanium) Metal Spray Forming Facility. The facility utilizes cold wall "skull" induction melting to produce up to 75 pounds of molten titanium (7000) cm3, 424 in3) for spray deposition. Recent results from both plants will be presented.
PLASMA SPRAY FORMING OF COMPOSITES: APPLICATIONS AND MARKET ANALYSIS: R.S. Thakur, Materials Procurement Division, Hindustan Motors Company, Indore, India; M. Sisodia, M.K. Bhargava, Dept. of Metallurgical Engineering, Malaviya Regional Eng. College, Jaipur, India 302017
Plasma Spray Forming is a droplet deposition method which involves the steps of melting, rapid solidification, and consolidation into a single operation. The advancement of technology enables the processing a wide range of metals, intermetallics, and ceramic matrix composites. The advent of Vacuum Plasma Spraying (VPS), which has opened a new dimension in Plasma Spray Forming of these materials, is outlined. The main considerations are being given to fiber reinforced metal matrix composites (MMCs) and ceramic matrix composites for their potential uses in different industrial fields, especially in making automotive engine components like pistons, cylinder liners etc. A brief case study specifically based on its annual production, cost factors, and marketing survey are discussed at length.
THE INFLUENCES OF AGING PRACTICE ON THE MICROSTRUCTURE AND TENSILE PROPERTIES OF SPRAY CAST Al-3Li-1Cu-0.6Mg-0.3Zr ALLOY SHEET: D.L. Yaney, Lockheed Martin Missiles and Space, Palo Alto, CA 94304; D.J. Chellman, Lockheed Martin Aeronautical Systems, Marietta, GA 30063
A spray cast aluminum-lithium alloy with nominal composition Al-3Li-1Cu-0.6Mg-0.3Zr (wt.%) has been successfully processed into 0.090 in. thick sheet. Following solutionizing at 540° C, selected combinations of quenching, stretching and aging treatments were evaluated in terms of their effect on the tensile properties of the final sheet product. Transmission electron microscopy was used to characterize the microstructural changes introduced by variations in aging practice. Although the maximum attainable yield strength was observed to increase with decreasing aging temperature, the double aging treatment of 3 hours at 170°C followed by 26 hours at 190°C, originally investigated by Gregson and Flower for similar direct chil cast Al-Li alloys, was shown to be effective in minimizing the in plane anisotropy frequently observed in Al-Li-Cu-Mg-Zr sheet products.
10:00 am BREAK
PROPERTIES OF SPRAY FORMED NON-HEAT TREATABLE ALUMINUM ALLOYS: M.F. Amateau, H. Patts, T.J. Eden, The Pennsylvania State University, Applied Research Laboratory, P.O. Box 30, North Antherton Street, State College, PA 16804
Non-heat treatable aluminum alloys rely on a combination of solid solution hardening and plastic deformation to achieve usable strength. The Al-Mn and Al-Mn-Mg alloys (3000 series) are used in applications requiring a high degree of deep drawing capability. Improved formability an drawability require high degree of ductility which depends upon rolling texture, recrystallization texture, grain size uniformity, and grain morphology. Spray metal forming produces a very fine and controlled starting microstructure which can have a profound effect on subsequent mechanical working and heat treatments. DC cast and spray metal formed Al-Mn and Al-Mn-Mg alloys were deformed to various amounts after which, microstructure and crystallographic texture were determined via x-ray diffraction pole figures. Subsequent recrystallization treatments were applied to evaluate the effect of the spray formed microstructure on recrystallization texture, recystallization kinetics, grain size, grain uniformity and mechanical anisotropy.
WEAR MECHANISMS IN SPRAY FORMED SILICON-ALUMINUM ALLOYS: D.S. Lee, M.F. Amateau, J.C. Conway, The Pennsylvania State University, Applied Research Laboratory, P.O. Box 30, North Atherton Street, State College, PA 16804-0030
Aluminum-silicon alloys, especially hypereutectic silicon compositions are finding increasing use in automotive components that are subjected to sliding contact. Conventional DC casting methods for processing these alloys result in unsuitably large primary silicon particles for subsequent extrusion and forging. Three spray cast hypereutectic aluminum-silicon alloys were processed to various states of extrusion, heat treatment and over aging. Wear measurements have been performed using the pin-on-ring configuration in the unlubricated condition sliding velocities of 4.46 m/s. The ring mating surfaces were grey iron. As cast B390 aluminum alloy was also wear tested for a standard of comparison. The worn surfaces were examined by scanning electron microscopy, electron beam microprobe analysis, and cross section microscopy to determine the nature and mechanism of wear.
THE USE OF TUNGSTEN BORIDE AS POWDER ELECTRODE MATERIAL FOR ELECTRO-SPARK ALLOYING OF STEELS: S.V. Nikolenko, Institute of Material Science, The Far Eastern Branch of Russian Academy of Sciences, Khabarovsk, Russia
The current development of technology is followed by the more and more complex demands for construction materials. In many cases the use of a combined material that has both the necessary hardness of the base and the high resistance of the outside layer to the environmental factors and wear is most efficient. This can be achieved by applying different kinds of protective coatings. Electro-spark alloying is one of perspective methods of coating deposition. This paper discusses the process of depositing the tungsten boride base composite powder material using a powerful impulse discharge, developed in a semi-closed volume with an electric field, accomplished by interaction of the powder units with the discharge plasma fed into the electrode space in gaseous environment. The process is conducted on a "Rasryad-3A" set, designed for coating with powder electrode materials.
GEOMETRICAL ASPECTS OF THE SPRAY FORMING PROCESS: B. Cantor, Department of Materials, Oxford University, Parks Road, Oxford OX1 3PH, UK
This paper describes a number of geometrical aspects of the shaping, heat flow, and microstructure in materials manufactured by different variants of the spray forming process. In particular that paper will discuss: (i) the transition from an initial chilled structure to a bulk equiaxed structure as spraying proceeds; (ii) the difference between thermal sprayed splat microstructures and incremental solidification; (iii) the effect of steps and other features on the substrate; and (iv) multiple sprays and multipassing with a single spray and their effect on banded structures.
AN INVESTIGATION OF THE CYCLIC FATIGUE AND FRACTURE BEHAVIOR OF SPRAY ATOMIZED AND DEPOSITED ALUMINUM-SILICON ALLOY: S. Anand, T.S. Srivatsan, Department of Mechanical Engineering, University of Akron, Akron, OH 44325-3903; E.J. Lavernia, Department of Chemical and Biochemical Engineering and Materials Science, University of California, Irvine, CA 92697
In this study an Al-17Si-4.5Cu-0.6Mg was synthesized utilizing the spray atomization and co-deposition technique to modify the distribution of the silicon phase in the alloy matrix. Detailed microstructural characterization studies were done using optical and electron microscopy observations with an emphasis on understanding the influence of spray deposition processing on distribution of the silicon phases in the alloy deposition processing on distribution of the silicon phases in the alloy matrix. Specimens of the aluminum alloy were cyclically deformed under stress-amplitude control over a range of amplitudes. The mechanisms and micro-mechanisms governing cyclic stress response and fatigue life of the alloy will be highlighted, compared with a conventional ingot metallurgy processed counterpart, and discussed. The kinetics governing the cyclic deformation characteristics and fracture processes of the spray processed and conventional ingot metallurgy processed alloys will rationalize in light of mutually interactive influences of microstructural effects, nature of loading, matrix deformation characteristics, macroscopic aspects of fracture, and ductility of the material.
*Research supported by National Aeronautics and Space Administration (Langley, Virginia) (Grant Number: NAGI-1619), with material support from Reynolds Company (Richmond, VA).
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