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Über dieses Buch

The Army Materials and Mechanics Research Center in cooperation with the Office of Sponsored Programs of Syracuse University has been conducting the Annual Sagamore Army Materials Research Conferences since 1954. The specific purpose of these conferences has been to bring together scientists and engineers from academic institutions, industry and government to explore in depth a subject of importance to the Department of Defense, the Army, and the scientific community. This 30th Sagamore Conference, entitled Innovations in Materials Processing, has attempted to focus on the inter­ disciplinary nature of materials processing, looking at recent advancements in the development of unit processes from a range of standpoints from the understanding and control of the under­ lying mechanisms through their application as part of a manufactur­ ing sequence. In between, the classic link between processing and materials properties is firmly established. A broad range of materials are treated in this manner: metals, ceramics, plastics, and composites. The interdisciplinary nature of materials processing exists through its involvement with the basic sciences, with, process and product design, with process control, and ultimately with manufacturing engineering. Materials processing is interdisciplinary in another sense, through its application within all materials disciplines. The industrial community (and the Army as its customer) is becoming increasingly concerned with producibility/reliability/ affordability issues in advanced product development. These concerns will be adequately addressed only by employing the full range of disciplines encompassed within the field of materials processing.



Section I

Affordability Through Technology: Bridging the Gap

Affordability has become a major concern to the Defense Department and to the Army in particular. A whole new generation of weapons systems was started on the drawing boards in the early 1970’s, and we are just now in the process of transitioning them to Procurement and Production. As we are transitioning these new systems to production we are also experiencing substantial cost growths.
Frederick J. Michel

Manufacturing and Productivity

One of the most significant problems currently facing the United States is the competitiveness of its manufacturing industry, which must be enhanced within the next s;everal years. In order to increase the productivity, the value added (i.e., selling price) must be maximized and the manufacturing cost must be minimized. Both of these depend on the quality of products and processes, which in turn depend on the design decisions made during the product and process development. The only means of assuring good design is to use scientific principles for rational decision making such as the synthesis Axioms. These manufacturing and productivity issues are discussed by analyzing the margin of profitability of the discrete mechanical parts manufacturing industry and by presenting the concepts and examples of the design Axioms. In addition to these short-term issues, there are long-term issues related to manufacturing and productivity, such as availability of natural resources, which may only be resolved through technological breakthroughs.
Nam P. Suh

Section II Process Modeling and Control I

Closed-Loop Control of Sheet Metal Forming Processes

The process of forming metal sheets involves large plastic deformation of the workpiece material. The outcome of these processes, therefore, are highly dependent upon the yield point and flow stress characteristics of the material. To overcome the problems associated with uncertain and highly variable forming properties, a control strategy is presented that is based on closing the loop around the forming process and workpiece rather than just the processing machine. In this way the variations in material properties and the uncertainty of die-sheet interface forces can be overcome on a part by part basis. The details of such a process are discussed briefly in the context of conventional NC control and in detail for sheet metal forming. Examples of closed-loop control are presented for brake forming, roll bending and general die forming. Specific experimental results for these cases illustrate that part control of sheet metal forming is quite feasible, and promises to improve the ultimate utility of such processes by reducing setup time, and by improving the part consistency.
David E. Hardt

Modeling of Organic Materials Processing

In an effort to reduce the empiricism involved in many polymer processing analyses and designs, this paper presents a finite element routine capable of predicting velocities, temperatures, stresses, and extents of chemical conversion in a variety of reactive polymer processes. The analysis accounts for diffusive, convective, and generation effects and also deals with transient situations.
After a brief introduction on the benefits of modeling polymer processes, the equations which govern nonisothermal reactive polymer flow are outlined. Using the equations, a finite element formulation is presented which results in a new element routine capable of analyzing complex flow domains. Program features include a penalty formulation to enforce fluid incompressibility, “upwind” weighting of highly convective terms, transient analysis capabilities, and iterative procedures to accomodate material nonlinearity.
The utility of the computer code is illustrated by sample analyses of representative industrial processes. These include pultrusion and reactive pressure flow which have parameters found in a number of other polymer processing operations. Material parameters as described in the literature are used and the effect of processing variables on the product internal temperatures and extents of chemical conversion are discussed.
Recommendations are made for future research and model development. These include alternative solution techniques to handle more complex geometries as well as the ability to model polymer behavior past the point of gelation.
Craig D. Douglas

Weld Quality Monitor and Control System

A non-contact Weld Quality Monitor (WQM) system is being developed to detect, identify, and correct for deviations from established welding procedures and conditions which lead to weld defects in real time. The WQM continually measures with conventional transducers all primary process parameters such as current, voltage, and travel speed, and computes weld quality parameters such as heat input and weld bead geometry. In addition, the WQM monitors the spectral signature of the welding arc by means of a high resolution microprocessor controlled spectrograph. Here, the presence of weld pool and arc atmosphere contaminants, flux and shield gas effectiveness, arc energy input, and penetration/dilution into the base material can be determined. The spectral response from the welding arc and measurements of process parameters are then normalized, compared to. preset operating limits, and processed in real time. Necessary adjustments to primary process parameters will be made by automated compensation devices to eliminate weld defects in real time. When necessary, the specific location of discontinuities will be provided to facilitate further inspection.
F. Kearney, Dawn Blackmon, William Ricci

Hot Rolling Simulation of Electromagnetically Cast and Direct-Chill Cast 5182 Aluminum Alloy by Hot Torsion Testing

Much of the metal produced today is fabricated by rolling, extrusion, or forging at elevated temperatures. Consequently, it is desirable to optimize hot working parameters such as reduction schedule, rolling speed, allowable extrusion ratio, extrusion speed, and working temperature to maximize productivity. In addition, it is important to hot work a metal a) in a microstructural condition that lends itself to easy hot working, e.g., properly homogenized, and b) to a microstructure that gives desirable properties in the end product.
J. R. Pickens, W. Precht, J. J. Mills

Computer Modeling of Energy Intensive Processes: Some Ford Motor Company Applications

The oil shortage and subsequent price revolution of the 1970s focused attention on energy intensive industrial processes. After the initial housekeeping savings, the question became how efficiently can these processes be run? In order to answer this question, work was begun to develop computer models of such processes. The modeling applications discussed in this paper are: cupola melting of iron; steel slab reheating; and semi-permanent mold aluminum casting. All of the models developed have the potential to be used in developing automated process control strategies. However, the iron melting and steel reheat models were directed towards energy savings as the primary objective, while the aluminum casting model was aimed at improving casting quality. This paper provides an overview of some results achieved in applying these models rather than a discussion of model construction. Details of model construction can be found in the original publications1–6. The approach in this paper is to illustrate by example the use of computer models to provide further understanding and insights into three energy intensive processes.
C. Bagwell, R. Creese, W. Evans, R. Fekete, C. Feltner, J. Grant, R. Hurley, D. Piercecchi, H. Smartt, S. Weiner

Section III Process Modeling and Control II

Process Modeling of P/M Extrusion

A powerful and efficient thermoviscoplastic finite-element program called ALPIP has been combined with advanced CAD/CAM methods for die design to permit mathematical and physical modeling of the extrusion of P/M materials. New constitutive equations and flow rules have been developed for porous materials as Well as for the case of fully dense sintered and hot-pressed billets. These new equations were integrated into the analysis software through a material data base. The modeling results clearly show that the streamlined die geometry strongly influences the state of stress and uniformity of metal flow, which subsequently controls the quality of the product in terms of, density, microstructure, and mechanical properties. Special attention is being given to the extrusion of RSR aluminum alloy powders as well as aluminum alloy powders containing SiC whiskers.
H. L. Gegel, J. C. Malas, S. M. Doraivelu

Development of a Computer-Aided Analysis Method for Sheet Material Forming Processes

The computer-aided engineering method can be incorporated in a number of material processing operations to reduce engineering, manufacturing and material costs. With this objective in mind, an interactive computer software package has recently been developed to predict the degree of success or failure of formed sheet metal parts at the design stage to minimize the traditional trial and error process. For example, given the material properties, the rate of deformation, the geometry, and loading boundary conditions, the program computes the distribution of major and minor strains in the part to be formed. Concurrently, the limiting strain forming limit diagrams corresponding to the particular material are computed based on the defect growth model. The computed strain distribution is then directly compared with the forming limit diagrams so that any design and processing changes can be made at the computer terminal. Several examples of computed results are presented which, in turn, are directly compared with the measured strain distributions obtained from the circular grid technique. Included in the experimental work are aluminum-killed steel, enameling iron, and high strength steel sheets.
Daeyong Lee, Catherine M. Forth

Recent Developments on the Application of the Finite Element Method to Metal Forming Problems

Most recent developments on the finite element method as applied to metal forming problems emphasize the application to three dimensional problems. There are some areas in metal forming where technological advancements can be made by full utilization of capabilities of the finite element method. An example is the development on the use of the finite element method for preform design. In this paper these developments are described.
Based in the rigid-viscoplastic forulation three-dimensional finite-element analysis was performed for the vlock forgings, using an 8-node hexahedral isoparametric element. The analysis of forging of a wedge-shaped block between two flat parallel dies is presented.
The objective of the analysis of spread problems, such as spread in rolling, in flat tool forging and spread in compression of noncircular efficiency, a simplified 8-node hexahedral element was devised and applied to the analysis of spread in rolling and in flat tool forging.
A development in the area of sheet metal forming is the analysis of forming of non-symmetric shapes. Based on the membrane theory, the formulation takes into account the finite strain, normal anisotropy, and the isotropic work hardening characteristics. New solution is shown for punch stretching of a rectangular strip.
One of the significant industrial problems in metal forming is the design of preforms. A new approach to this problem has been introduced. The concept involved in the approach is to trace backward the loading path in the actual forming process from a given final configuration by the finite element method. The application of the method to preform design in shell nosing is discussed.
Shiro Kobayashi

Section IV Processing from the Liquid State

Recent Material and Process Developments in RIM and RRIM

The use of reaction injection molding (RIM) and reinforced reaction injection molding (RRIM) for the production of large parts, especially in automotive applications, is currently quite commonplace.1 In the RIM process, shown schematically in Figure 1, two liquid components are pumped at high throughputs and pressures to a self cleaning impingement type mixing head and then into a mold where the polymerization reaction occurs and the part is formed within seconds.2 RRIM is basically the same process but short fibers or fillers are added to one or both of the components in order to obtain various special properties. Certain equipment modifications must be made in order to handle the viscous, and often abrasive slurries.
W. J. Farrissey, L. M. Alberino, R. J. Lockwood

Precision Injection Molding of Thermoplastics

The paper reviews the state of the art of injection molding. The tolerances in terms of shrinkage and warpage are reviewed for major plastic resins. The molding process is discussed in terms of flow orientation and control of melt and machine parameters to achieve good properties and dimensions. The paper looks at automatic process control for precision parts. The use of microprocessor control is reviewed. The paper will discuss both ram velocity control and melt pressure control. The use of such a control unit in the molding of high quality optical polyurethane lenses is described. The use of computer modeling and computer aided design in the simulation of molded plastics is described from a commercial viewpoint. Also, the role of cooling of the part and the feasibility of the proposed part is described. Finally, the paper describes the need for rheological and thermodynamic data that are required for the computer modeling.
Nick R. Schott

Oxide Single Crystal Growth

Processing of ceramics from the liquid phase includes glass formation, glass-ceramics, fusion casting of refractories eutectic solidification, and single crystal growth. Ceramics include oxides, borides, carbides, and nitrides. This paper will, however, only discuss oxide single crystal growth as a form of processing. Borides, carbides, and nitrides generally sublime at very high temperatures rather than melt and, therefore, they are not processed from the liquid phase. Oxides can be processed from the liquid phase. The reasons why it is preferable to process them as single crystals if high technology applications are required will be discussed. The paper will also cover the factors that have allowed oxide single crystal growth to go from the laboratory to the factory by covering the modern crystal growth processing techniques. Materials and applications will be covered in the course of discussion.
Dennis J. Viechnicki

Recent Advances in Solidification Processing

Control of the cast structure is the underlying object of solidification processing. Recent advances and developments in solidification processing are making possible the production of high purity castings, fine grained super alloy and titanium ingots, rapidly solidified structural components and castings having unique microstructures. In addition, recent advances in processing technology have developed which now allow us to have better producibility and reliability in aluminum castings. These developments have all stemmed from a good understanding of the science of solidification processing as well as an appreciation of the merits of structural control via processing. Specifically, the following recent developments will be reviewed and discussed: (i) Vacuum Arc Double Electrode Remelting (VADER); (ii) Rapid Solidification by Plasma Deposition (RSPD); (iii) rapid cycle casting of ferrous components by Diffusion Solidification; (iv) refining of the melt via filtration prior to casting; and (v) thermal analysis of aluminum castings.
D. Apelian

Processing of Steel Ingots for the Production of High Quality Forgings

The subject paper describes recent advances in the production of alloy steels of a 4335 + V alloy used for the manufacture of high quality forgings. The framework of the discussion will be the impact of new steel production methods upon the producibility/reliability/affordability of the final end item.
Vito Colangelo, Steve Tauscher

Section V Processing of Particulates

Metal Alkoxy-Derived Powders

The use of metal alkoxides to prepare high purity oxide powders is emphasized. Thermal and hydrolytic decomposition of metal alkoxides, M(OR)n, have been employed to obtain submicron size <50nm single and mixed oxides powders. The alkoxy technique in powder synthesis allow the mixing of residual concentration of an alloying element to be done at something approaching the molecular level. The high surface activity associated with the alkoxy-derived powders make possible relatively low temperature processing of the powder compact to near theoretical density and uniform fine grain size bodies. Transmission electron microscopy, X-ray, ir, DTA and BET surface area measurement are used to show nucleation, crystallite growth and morphology as well as polymorphs of the oxide powder synthesized and microstructural features observed.
K. S. Mazdiyasni

“SHS” Self-Sintering of Materials in the Titanium-Boron-Carbon System

Refractory ceramics (e.g., borides, carbides, and nitrides) are families of materials having desirable properties for a variety of DoD applications. Their key properties are high hardness and strength, along with resistance to heat, corrosion, and wear. Conventional methods for producing these materials as monolithic ceramics can be very expensive. An alternative to these conventional methods consists of using the heat generated in exothermic reactions to simultaneously form the desired phases and densify the product. This processing technique is termed “Self-Propagating High-Temperature Synthesis (SHS).” This technique results from the large exothermic reaction between the elemental constituents of a refractory compound. Several key advantages of SHS over conventional processing methods are: 1) a high rate of synthesis (seconds versus hours or days) 2) attainment of equilibrium; 3) improved purity due to loss of volatiles; and 4) no need for expensive energy-consuming furnaces.
The Ti-B-C system contains at least four high-temperature refractory phases (TiB2, TiB, TiC, and B4C) which can be produced by SHS. In particular, compositions along the Ti-B4C composition join have been critically investigated. Through extensive characterization of precursor powders our studies show that small variations in the titanium particle size distributions have a large effect on the processing aspects of SHS (reaction initiation, rate, weight losses) and influence the final product characteristics (microstrueture, density, phase composition).
N. D. Corbin, T. M. Resetar, J. W. McCauley

Vibrational Fusing of Plastic Particles

VIM molding relates to a process and apparatus for molding plastic articles from particulate plastic material.
Robert P. Fried

Synthesis of Ceramic Powders and Surface Films From Laser Heated Gases

Two new processes have been developed that are based on laser heated gases. Both permit unusually precise levels of process control and thereby materials having superior properties.
The powder process yields Si, Si3N4 and SiC powders that are uniform in size, non-agglomerated, small diameter, spherically shaped and high purity. Manufacturing cost analyses show that sub- micron powders can be made with an energy cost of approximately 2 kWhr/kg and a dollar cost of 2–3.30 $/kg exclusive of the costs of feed materials. This type of process should be capable of producing technically superior, lower cost submicron powders than existing processes.
The laser induced chemical vapor deposition process (LICVD) causes reactant gases to be heated by absorbing IR light from a laser beam that passes parallel to the substrate surface. Laser heating permits independent control of gas and substrate temperatures while operating in a conventional thermally activated CVD mode. For hydrogenated amorphous silicon films, this is particularly important because deposition rates are determined by the high gas temperatures and film properties by the low substrate temperatures. Spin density, hydrogen content, electrical conductivity and mobility gap properties show the LICVD process capable of producing very high quality films.
John S. Haggerty

Dynamic Compaction of Metal and Ceramic Powders

The advent of powders having unique properties derived from special processing such as rapid quenching offers the potential for materials with significantly improved performance capabilities. The fabrication of these powders into useful structures or components by conventional powder fabrication techniques without unfavorably altering or even destroying their unique properties is oftentimes impossible. As a result, new approaches and techniques for fabricating these and other powders with unique properties are being sought and investigated.
Vonne D. Linse

Section VI Advances in Machining Technology

High Metal Removal Rate (HMRR) Machining

The need for improving the productivity of machining operations has encouraged the development of new concepts and techniques, such as thermal machining, as well as high speed and ultra-high speed machining. High metal removal rate machining shares the goal of improving productivity with the others, but its approach is more evolutionary in nature; it attempts to take advantage of step advances in machine and cutting tool technologies, as they occur, and to incorporate them into machining operations with a minimum of delay.
Adam M. Janotik, Jonathan S. Johnson

High-Speed Machining

The term “high-speed machining” (HSM) is a relative one from a materials viewpoint because of the vastly different speeds at which different materials can be machined with acceptable tool life. For example, it is easier to machine aluminum at 6000 surface feet per minute (sfm) than titanium at 600 sfm. Because of this difference, and the fact that speed determines to a significant degree whether a material will form continuous chips or segmented, shear- localized chips, one way of defining high-speed machining is to relate it to the chip formation process. Localized shear occurs when the negative effect on strength of increasing temperature due to intense plastic deformation is equal to or greater than the positive effect of strain hardening. In this context, high-speed machining for a given material can be defined as that speed above which shear-localization develops completely in the primary shear zone.
D. G. Flom

Advances in Precision Grinding

The army is not alone in its quest for producibility, reliability and affordability. Industry in general has the same concerns and is searching for producivity and total cost per part improvements. The economic situation since the late 1970Ts has significantly changed manufacturing management’s attitude toward change — especially the larger world class manufacturers like Saginaw Steering Gear, Garrett Turbine, Caterpillar Tractor — to not only be receptive to new processing methods but to be proactive in searching for them, providing engineering resources to work on them, and implementing them in their manufacturing procedures.
Robert L. Mahar

Section VII Surface Treatments

Ion Implantation of Metal and Non-Metal Surfaces

For material surface modification, the ion implantation process has been found to have beneficial effects on surface-sensitive properties such as hardness, wear, coefficient of friction, fatigue, aqueous corrosion, oxidation, adhesion, optical characteristics and catalytic activity. These are in part due to the fact that ion implantation is inherently a non- equilibrium phenomenon which can substantially alter surfaces of metals and non-metals to impart new characteristics. From the chemistry standpoint, conventional alloys can be formed on the surface without affecting the bulk material. More importantly, since elements can be introduced in concentrations far beyond equilibrium solid and compound solubility limits, the process may be used to form unusual alloys, metastable phases, and morphologies which are impossible to prepare by other methods. The technique involves directing a beam of high energy ions, in the one hundred kilo electron volt and higher range in energy, at a substrate surface, under vacuum. An analyzing magnet is used to separate the ion or ions of interest, and thus, a pure isotope species is energetically injected into the surface to a depth up to several thousand angstroms. Recent variations in direct beam implantation include ion beam mixing, simultaneous deposition and implantation, and ion cluster beam deposition. These processes result in thicker alloy deposits and higher additive concentrations, along with implantation. Discussion of applications of implantation will be limited to friction and wear and general corrosion. Results in the literature document wear improvement factors of between two and twelve times for treated cutting tools and dies. In corrosion, one program has shown substantial improvement of M50 steel bearings in resistance to chloride in lubricating oil. Applications of implantation to non-metal is much more limited. Investigators have examined effects of implantations on silicon carbide, aluminum oxide and titanium diboride. Miscellaneous investigations on non-metal include studies on polymers and polymer films, and on glasses.
Charles Levy, James K. Hirvonen

Surface Modification by Plasma Polymerization

Plasma polymers are surface coatings formed in a plasma by the fragmentation of “monomer” molecules, the formation of reactive sites on surfaces (including newly formed plasma polymer) in contact with the plasma, and the reaction of monomer fragments with the surface and each other. Such films are formed in a glow-discharge, a plasma (electrically neutral ionized gas) formed (and sustained) by an electric field in a partial vacuum (less than 10 Torr pressure). As a consequence of the low pressure. electrons are characterized by electron temperatures of 10,000° C, average electron energies of 1–10 eV and non-equilibrium with gas molecules.1 The temperature of the latter is therefore close to ambient.
Nicholas Morosoff

Advances in Carburizing — Vacuum Carburizing

Steel components having appropriate combinations of wear resistance, mechanical strength, impact strength, etc., especially at higher temperatures (above 500°F) can be produced by employing the well-known conventional carburizing process or a suitably modified process. In carburizing a carbon-rich layer ranging from ~.005 inch to more than ~.100 inch is produced on some or all of the surfaces of a relatively low carbon component. By suitable post-carburizing treatment the carbon-rich layer can be caused to be quite hard (> 60 Rc) but also relatively brittle while the low carbon interior (< 35 RQ) retains adequate strength and ductility.
Samuel J. Hruska

Electroplating of Refractory Metals

Fused salt electroplating offers the prospects for producing refractory metals in a variety of technologically important forms: coatings of metals, alloys, and compounds; thin films and graded interfaces; and ceramic to metal interlayers. Previous results of fused salt electroplating of refractory metals are reviewed. New techniques of studying the electroplating process, process control, and evaluation of the deposit are discussed.
Georges J. Kipouros, Donald R. Sadoway


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