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International Electron Beam Welding Conference Session 2

Home > Educational Programs > International Electron Beam Welding (IEBW) Conference Session 2

Tuesday, November 17 – Wednesday, November 18, 2009 • 9:00 AM – 4:15 PM
Chair: Ernest Levert
Member of AWS, FMA, SME, NAM, or PMA: $550
Nonmembers: $685 • Registration Code: W28
Room N231

The American Welding Society, DVS (German Welding Society), and The International Institute of Welding are organizing their first International Electron Beam Welding Conference. This event will be held in conjunction with the Fabtech International & AWS Welding Show. It will include a two-day technical program plus a half-day tutorial sponsored by the Pro-beam foundation. IEBW will bring together scientists, engineers and technical personnel from around the globe involved in the research, development, and application of electron beam welding processes.

In addition, on Monday, November 16th from 9:00 AM to 3:00 PM, a free student tutorial on electron beam welding is being presented by Pro-Beam Foundation (Germany).

Session 1 | Session 2 | Session 3 | Student Tutorial

Conference Program

The Electron Beam as a Tool of Both Nano Science and Micro Technology: From UHV Evaporation to Micro Electron Beam Welding

10:30 AM – 10:50 AM
M.Merkel*, K.Wrobel*, M.Escher*, M.Zobac**, I.Vlcek**, L.Dupak**, F.-H. Roegner***, G.Mattausch***, A.Reichmann*** *FOCUS GmbH, Huenstetten, Germany **Institute of Scientific Instruments of the ASCR, Brno, Czech Republic ***Fraunhofer Institute for Electron Beam and Plasma Technology, Dresden, Germany
The electron beam as a highly efficient heating source is well known since its first use for the melting of tantalum at the end of the 19th century. During the first half of the last century, its ability to evaporate, to drill, and to weld of even refractive metals has been discovered. After the Second World War people started to use this exciting properties for a wide range of industrial applications commercially.

We started to use the electron beam for ultra-clean vapor deposition of very small amounts of numerous materials in 1990. Our ultra-high-vacuum electron beam evaporator is today a standard tool in nanoscience laboratories . We will show how it works together with some application examples.

A growing request for new joining methods applicable to micro technology did encourage us to develop a dedicated micro-electron beam welder during the last years. We ended up with a desktop-sized instrument looking more similar to an electron microscope than to a common e-beam welder. This is not only a formal difference. Its design philosophy follows a number of technical solutions what are commonly used for scanning electron microscopes. Based on a long-erm experience on the field of electron optics, it is suitable to match the needs of a wide range of challenging joining tasks: from micro-mechanical and microsystem technological ones to a lot of precision technological applications, how they are common nowadays e.g. for medical technology or sensor industry. We will present some examples and will give a brief outlook in terms of the challenges of the future in this field.

Prediction and Control of Distortion and Residual Stresses in Electron Beam Welding

10:50-11:10 AM
Nick Bagshaw and Chris Punshon TWI Ltd.
Electron beam welding is recognized as an attractive method for minimizing distortion during welding, and is used frequently to join parts which are already finally machined or close to finished size. In such cases, before EB welding, it is of great value to be able to estimate the level of accuracy that will be achieved and the dimensional stability of the assembly throughout its service life. This presentation describes the development of a finite element (FE) modeling technique, validated by experiment, for predicting and understanding the development of residual stresses and distortion during EB welding, particularly in circular components. The use of this method for optimization of welding procedures and residual stress mitigation methods is described and illustrated through a number of practical examples.

Development of Local Vacuum Electron Beam Welding for Rapid Fabrication of Large Structures

11:10-11:30 AM
Chris Punshon TWI Ltd.
Electron beam welding is generally carried out in a vacuum chamber, which is an attractive process characteristic offering many advantages in terms of containment, avoidance of contamination, and minimal metallurgical disturbance. To date, however, the necessity to conduct processing in a high vacuum atmosphere has largely restricted the application of the process to components and structures that can be entirely contained within a vacuum chamber.

This paper describes the innovative development of systems allowing the generation of high-power electron beams for use at "reduced pressure"(~1 mbar), uniquely combined with developments in mobile, local seals. The requirements for sealing and pumping at this pressure are much less onerous than with high-vacuum EBW, thus facilitating the application of the process to much larger structures and components. A number of practical examples are described of how these process developments have been used successfully, illustrating the potential for application in a range of industry sectors and materials.

Developments in Sub-10kW Electron Beam Equipment, Processes and Monitoring

11:30 AM – 11:50 AM
Bruce Dance, TWI Ltd
When first developed, electron beam process equipment was limited in beam power. Developments in equipment mean that processing is now possible over a huge range of beam powers and qualities. However, despite the possibilities of higher beam powers, a huge amount of commercial EB processing is still carried out at low powers (<10kW). In addition, although benefitting from modern control systems, the majority of EB process hardware still uses electron gun generator designs that are apparently little changed in the last 20 years, in stark contrast to laser equipments.

This paper reviews electron beam generator performance in relation to common process requirements, as well as the demands of more recently developed EB processes. Beam probing and measurement data are presented. Examples are given in which processes that demand specific beam qualities have been made possible by improved beam generation and control.

Investigations Relating to Electron Beam Welding of Dissimilar Metal Welds Based on Cast Iron

11:50 AM-12:10 PM
Karsten Rüthrich, TU Bergakademie Freiberg, Germany; Martina Mangler, TU Bergakademie Freiberg, Germany; Rolf Zenker, Zenker Consult Mittweida, Germany
The combination of casting and welding in hybrid designs is a very interesting direction of development, especially in the automotive industry. Cast iron materials are either not weldable at all or weldable only with large-scale additional technological measures (pre-heating, post-heating, filler material).

Electron beams are characterized by good deflectability, thus making it possible to realize multi-spot and/or multi-process technologies. This means that different processes influencing the thermal regimes in the welding zone may be carried out in one processing step.

First will be presented what EB multi-spot techniques and multi-process technologies mean and which opportunities are provided by them in connection with welding.

Furthermore, results of investigations relating to multi-spot welding of dissimilar metal welds based on cast iron (same-type, related-type) and unrelated-type welds of cast iron with steel will be presented. In addition, actual results of welding obtained using multi-process technologies (pre- and/or post-heating) in one processing step will be presented.

Lunch

12:10 PM – 1:10 PM
(Hosted by AWS C7B Committee)

Joint Tracking with the Electron Beam Offline and Online – An Important Welding Automation Tool

1:10 PM – 1:30 PM
Dr. Michael Mücke, Carsten Scheiblich, All Welding Technologies AG (Germany)
The electron beam is used in electron microscopy to image the smallest of structures. Highly dependent on surface structure, it capitalizes on the angle of backscatter from electrons reflected off the target material. This process is often used for imaging purposes in electron beam welding systems. The viewing advantages over photo-optical methods such as telescopes or CCD cameras include a markedly superior depth of field and elimination of the need to illuminate the target surface. The quality of these images has sufficient resolution for viewing typical joint forms.

The electron beam in EB welding systems is already being employed to identify joints for some welding projects. This process does not require a complete image of the surface. The signal provided by backscattered electrons from a single deflection line perpendicular to the joint is sufficient. The position of the joint can be ascertained by a change in the signal that occurs when the beam is reflected differently off the joint.

This process is customarily used to statically determine the joint position on one or a few points before the welding begins. Errors in the positioning of the target piece are measured and the welding process is adjusted accordingly. Even small tolerances in the assembly of a target piece can be offset. Other processes use a search beam to probe multiple points along the entire course of the joint before welding begins (offline). Measurable deviations from the reference position are saved and corrected during the welding process. In so doing, even residual magnetic fields in the target piece or clamping fixture can be compensated for.

Deflection technology in electron beam welding system hardware and software has seen significant improvements during the past several years. Using deflection frequencies as high as 200 kHz, it is now possible to conduct joint tracking during the welding process (online). The electron beam periodically springs out of the weld pool to perform a nearly continuous scan perpendicular to the weld. It moves far enough forward to take measurements ahead of the melt zone. If the weld focus is not on the surface of the target piece, the focus position is switched to joint identification in order to receive a clear surface joint signal. While the beam continues to weld after rebounding into the weld pool, the CPU calculates the deviation from the programmed reference position and corrects the weld position by deflecting the electron beam.

Examples will be used to illustrate the individual processes. The results document the current state of this technology. A view of prospective opportunities in electron beam process automation will be provided.

Fast Beam Deflection and Beam Quality– Keys to Economic High Quality Electron Beam Applications

1:30 PM – 1:50 PM
Uwe Clauß, pro-beam AG & Co. KGaA (Germany)
Since its first introduction to the industry the control systems of electron beam machines have gone through an enormous development. With the availability of fast amplifier components and digital beam controllers, the advantages of the electron beam have further increased, making it a truly software-controlled thermal processing tool.

Modern beam controllers enable multi-beam and multi-focus technologies, where the beam is split in up to 60 or more individual beams. These technologies can reduce the processing time by parallel processing or improve the quality by optimized thermal expansion of the part. Multi-process technologies, where several processes are performed in one run (e.g. welding and cosmetic treatment), further extend the application range of the electron beam process.

Fast beam deflection in conjunction with electron-optical monitoring is the fundamental component for advanced seam tracking systems. They allow automating the EB application in order to optimize the process costs and improve the quality of the results in a reproducible manner.

Basis for a high quality of the EB process is the condition of the tool the electron beam itself. By introducing the beam parameter product to the electron beam, reliable information about the quality of the beam can be derived. Implemented into automatic beam alignment systems, repeatable results with high quality can be achieved.

Break

1:50 PM – 2:00 PM

Reconstitution of Fracture Mechanics Test Specimens by Electron Beam Welding

2:00 PM – 2:20 PM
Peter Petrov, Institute of Electronics
Changes in the material properties due to neutron irradiation are monitored by means of surveillance programs. Specimen surveillance programs for reactor pressure vessel (RPV) materials are among the most important parts of inspection programs that are necessary for realistic evaluation of RPV lifetime.

In nuclear power plants (NPP), Charpy - Cv specimens are used to assess the RPV embrittlement. The surveillance capsule assemblies in each capsule contain typically 12 Cv and 3 tensile specimens. However, to address future plant life management, especially for older NPP's, it is necessary to obtain more statistics on the pressure vessel embrittlement. Reconstitution technology allows performing additional Cv or fracture toughness tests on a limited amount of available material and can contribute to a better characterization of the material and, therefore, to a better evaluation of the embrittlement degree of RPV steel due to neutron irradiation.

This presentation reports results from reconstitution of Cv-type and CT specimens by electron beam welding. The experiments were carried out using a 15 kW Leybold Heraeus welding unit. The material used in this study is 18MND5 steel. Investigations were made of structural changes of metal in welds and heat-affected zones. Cv impact tests showed good agreement between the original and reconstituted specimens.

Non-Vacuum Electron Beam Cutting

2:20 PM – 2:40 PM
N. Murray, A. Beniach, R. Konya, Dr. Th. Hassel, Prof. Dr-Ing. Fr.-W. Bach, Institut für Werkstoffkunde (Germany)
The main domain of non-vacuum electron beam (NVEB) technology has so far been high-speed and high-quality joining. It is of great interest to find further uses for this efficient technology. Current research by the NVEB-group of the Institute of Material Science at the Leibniz University of Hannover focuses on the implementation of the NVEB process to the cutting of metal plates. Experiments are conducted on a PTR NVEB welding system with an acceleration voltage of 175 kV and a maximum power of 25 kW. First experiments with this equipment showed that it is possible to cut 20-mm-thick plates of mild steel. A cutting speed of 1 m/min at a beam current of 140 mA was achieved. Despite the well-known widening of the electron beam due to the scattering of the electrons in atmosphere, the resulting face is straight and of high quality, with only little residual melt drops at the lower edge. At the moment, preparations are being done to use a gas jet to blow away molten material from the cutting area to further improve surface finish of the cut. To evaluate the possibilities of expanding the work domain of the NVEB, process experiments will be done using the electron beam for weld preparation and welding within two steps on the same equipment.

Modeling of Heat Transfer and Fluid Flow during Keyhole Mode Electron Beam Welding

2:40 PM – 3:00 PM
R. Rai, T.A. Palmer, J.W. Elmer*, and T. DebRoy, Department of Materials Science and Engineering, Pennsylvania State University; *Lawrence Livermore National Laboratory, Livermore (USA)
A three-dimensional numerical model of the turbulent heat transfer and fluid flow in keyhole-mode electron beam welding has been developed and validated. In addition to solving for the enhanced heat and mass transport due to turbulence, this model also considers the heat balance at the keyhole walls and the variation of vapor pressure in the keyhole and the keyhole wall temperature with depth. Since the model takes into account these various physical processes, it can be applied to materials with different thermo-physical properties. In this work, the model was validated using several 304L stainless steel welds made at fixed input power but different power densities achieved by variation in the focal spot size, and the calculated and experimental weld geometries were in reasonable agreement. Peclet number calculations show that convective heat transfer is very significant, and computations performed in the presence and absence of convection also demonstrate the important role of convection on the formation of the resulting weld geometry.

Welding of an Anaesthesia Tank of Aluminum Die Casting with Multi-Jet Electron Beam

3:00 PM – 3:20 PM
O.Krahn, H. Pries, K. Dilger, Institute of Joining- and Welding-Technology of the Technical University (Germany)
The process of aluminum die casting, which produces near-net-shape, complex, and thin-walled prefabricated parts of aluminum, finds more and more applications in all areas of the industry because it has economic advantages compared to other processes in productivity. The technically most-used molding process of aluminum die casting products is fusion welding, which shows multiple problems. The safe production of pore-free welding seams requires an expensive optimization all over the die casting process as well as the choice of a qualified welding process.

An innovative approach to solve these problems is the integration of the electron multi-jet beam welding in the manufacturing chain.

To avoid distortion at small welding seams, high-frequency deflection of the electron beam is used, to connect the welded joint and the local successive fusing in one process step to reduce the porosity. This aided project shows successfully that it is possible to qualify the welding of an anaesthesia tank in normal die casting quality with the electron multi-jet beam as an economic and applicable operation of mass production for premium, pressure-tight units.

It was shown that an optimization of the welding parameter and the welding sequence over the multijet electron beam can reduce the porosity of the welding seam under 8%. That puts us in a position to fulfill the technical requirements for medical products.

Micro Electron Beam Welding of Metal Foils and Wires

3:20 PM – 3:40 PM
Backhaus, Dorfmüller, Dr. Olschok, Prof. Dr.-Ing. Reisgen, ISF - Welding and Joining Institute, RWTH Aachen University

The Electron Beam as Versatile Tool for the MEMS and Precision Engineering Technology

3:40 PM – 4:15 PM
Dr.-Ing. Klaus Dilger and Prof. Dr.-Ing. Stefan Bohm, Technische Universität Braunschweig; Dr. Th. Löwer and Jan Bärtle, pro-beam AG & Co. KGaA, (Germany)
Under the framework of a public sponsored project, an electron beam -based production line for micro systems was developed and built. Different processes like structuring, joining, material removal, measuring and visualization can be performed in one installation without tool changes in a precise and flexible manner.

The electron beam is not only providing the machining capabilities, but also the opportunity to observe the work piece and production steps by the use of backscattered electrons, presenting a flexible tool for quality assurance.

In the last years, detailed studies about micromachining processes using an electron beam were performed on different types of machines, like a scanning electron microscope or conventional electron beam welding machines. But in comparison to this attempts our built micro-electron beam machine is much more stable, more precise, the power is between 1 watt and 500 watts and the beam diameter less than 50 microns.

The latest results of the machine development and the experiments will be presented.

Session 1 | Session 2 | Session 3 | Student Tutorial