Electron Beam Melting and Coating 2006
Coincidentally, 2006 was the year that saw the placement of orders for almost 10 megawatts of EB melting furnaces, scheduled for commissioning from early 2007 through 2008. This is the first expansion of EB melting capacity since the mid-’90s.
The papers presented developments in Ti, Ta, Nb, Zr, V, special facilities and related topics.
The ConferenceT.F. Sorvan of ATI Allvac (Richland, Wash.) started the presentations with a paper co-authored by E.J. Haas and T.D. Bayha on Ti production in the Richland facility. This 5.4-megawatt furnace is the largest EB cold-hearth melting installation in the world, and it is capable of melting in excess of 50,000 pounds per heat. Commissioned in 1997, it has supplied various industries with large slab, 30-inch-diameter ingot and remelt stock for vacuum-arc melting with CP Ti being the bulk of its output. Its technical challenge today is to develop lean manufacturing techniques to produce ingots of various geometries of Ti6Al4V meeting aerospace requirements.
David Trip of TIMET (Morgantown, Pa.), the largest EB melter in the world, followed with a presentation co-authored by Stacey Nyakana, M. McCain and John Fanning on chemical homogeneity of Ti alloys produced by an EB single melt. This process – with manufacturing and commercial advantages – offers reduced melting time, reduced conversion operations, increased yield and decreased cycle time. These advantages are increasingly important in a marketplace constrained by raw material and production capacity. Airframe and aero-engine manufacturers require that EB single-melt material meets the needs for their applications, with chemical homogeneity in the finished products being the critical component. A number of heats of Ti6Al4V, Timetal, 54M (TM) and Timetal 215 (TM) were systematically analyzed to determine homogeneity.
The next paper, authored by M. Neumann of von Ardenne Anlagentechnik and co-authored by F. Odebisi of TIMET, presented results of Ti melting with the EH800V EB gun by Ardenne (Fig. 1) – the most powerful in its stable. Performance parameters and experience of this gun, in comparison with that of the EH750s that power TIMET’s furnaces, were presented. A look at further developments and other installations with the 800kW gun was also given.
Louis E. Huber of Cabot Supermetals (Boyertown, Pa.) followed with a presentation titled “Tantalum Electron Beam Ingot as a Core Technology for Customized to Market Mill Forms.” This company’s technology to uniformly purify 300-mm-diameter Ta ingots has permitted optimal customization of all its mill products with grain size, recrystallization, deep draw and mechanical characteristics using a balanced process designed to meet chemical process and thin-film market applications.
The Russian contribution was by S.G. Achtonov and Associates from OAO Chepetsky Mechanical Plant and FGUPVNIIIM on melting and refining niobium using the ALD-manufactured EB furnace – type ES2/100/600 (Fig. 2). Processing parameters and analytical results of the Nb produced in this furnace were presented.
“Process Analysis and Quality Control in EBMR Refractory and Reactive Metals” was the Bulgarian contribution from Elena Koleva of the Institute of Electronics (Sofia, Bularia). It discussed metallurgical processes during electron beam melting and was aimed at determination of proper processing parameters. Thermodynamic conditions in refinish scrap and simulation of the processes for Ta, Mb, Ti, Zr and Nb were the basics for creating statistical models of the relationship between the molten pool and the process parameters.
E. Ladokhin from Kiev, Ukraine, followed with a paper co-authored by his associates V. Chernyvsky, A. Gladkov and T. Lapshuk, “New Techniques for Tube Billet Castings in an Electron Beam Installation.” The results of the investigation of cast billets production for Zr 1%, Nb with EB melting with electromagnetic stirring and bottom pouring are presented. It included three methods – casting in chilled mold, centrifugal casting and casting in copper water-cooled mold – all of which resulted in satisfactory products. Structure and mechanical properties were studied, and 48 x 8.5 mm tubes were produced by hot-pressing technique.
Douglas C. Hughes of Reading Alloys followed with an overview of his company, which grew from a two-man operation in the early 1950s to more than 150 people today. He also reviewed the company’s two electron beam furnaces – a 260kW and a double 200kW unit. Vanadium is the primary product of the company.
Electron beam melting, the Indian scenario, was presented in a paper by A.K. Ray from Bhabha Atomic Research Center in Mumbai. The Department of Atomic Energy has developed a number of laboratory-scaled EB units for melting of refractory metals. Among others, melting parameters have been optimized for double melting of Nb to achieve reactor-grade specifications as well as future plans for Nb use in superconducting activities.
D. Esser of ALD next presented a paper co-authored by his associates and J.P. Belot titled “Melting and Empirical Results of Al Evaporation in Electron Beam Cold Hearth Refining of Ti6Al4V.” As Al evaporation takes place when processing this alloy, it is critical for the ability to produce an on-spec material to understand and predict this loss. A model developed by J.P. Belot is employed to characterize the Al loss. Comparative data on the model and actual results are presented.
Two German contributions followed. The first, by H. Morgner and his associates from Fraunhofer Institute for Electron and Plasma Technology (FEP) in Dresden, was titled “Transparent Abrasion Resistance Layer on Plastic, Metal and Glass Substrates by Plasma Activated High Rate Deposition.” Plastic and metal materials have different but excellent and valuable properties, but both lack high surface hardness. Coating these with hard oxides can broaden their uses. Coating problems are discussed, and resulting hardness of the oxide films is presented.
Electron Beam EvaporationWhile no papers on the subject were presented at the conference, EB evaporation today is the principal technology in turbine-blade coating for higher operating temperatures and longer life. All jet-powered aircraft flying today have EB-coated turbine blades, mostly with yttrium-stabilized zirconia. The second German paper was “The Development of a Scanned Electron Beam X-ray Tomography System for High Speed Imaging of Technical Multiphase Flows” by U. Haupel and associates from the Institute of Safety Research Rosendorf, FEP Dresden and the Institute of Nuclear Technology and Energy System at the University of Stuttgart. Because of the inadequacy of the existing technique, this group initiated development of a flexible-scanned EB X-ray apparatus that offers a number of different measurement features, including linear scan, multi-plan tomography and phase velocity measurement at a recording speed of up to 10,000 images per second.
“Advances in High Power Beam Technology for Large Scale Materials Processing” by Chris Punshin of TNI (Great Britain) discussed a system for the generation of high-power electron beams for welding at reduced pressure (~1 mbar) and the developments in mobile local seals. A number of practical examples are described, illustrating their potential for a wide range of applications in different industry sectors. While not novel, these activities indicate possible renewal of interest here.
The last paper, by Bruce Dance of TNI, presented facts on EB texturing and Surfi-Sculpt, two novel EB material-processing technologies. The texturing produces rapid and controlled displacement of material at approximately 1,000 locations per second, while the Surfi-Sculpt process is multiple interactions of an electron beam to create complex slots, holes and protruding features (Fig. 5), all of which are apparently finding applications in many areas. Details on these and equipment developments that make them possible are described. The conference proceedings are available in a CD issued by von Ardenne Anlagentechnik GmbH and can be obtained from them. IH
For more information: Mr. Bakish is principal of Bakish Materials Corp., P.O. Box 148, Englewood, N.J. 07631; tel: 210-567-5873; fax: 201-567-6684; e-mail: email@example.com
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