DVS_Bericht_368_LP

2021
DVS-BERICHTE
International
Electron Beam
Welding Conference

S T R A H L T E C H N I K
STEIGERWALD STRAHLTECHNIK
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IEBW – International
Electron Beam Welding
Conference
Lectures of the 6th International Conference taking
place online on 9 to 10 March 2021
Organiser:
DVS – German Welding Society, Düsseldorf

Bibliographic information published by the Deutsche Nationalbibliothek
e etce ationaliliote lit ti lication in te etce ationaliliorae
detailed bibliographic data are available in the Internet at http://dnb.dnb.de.
DVS-Berichte Band 368
ISBN 978-3-96144-133-4
The lectures are printed in form of manuscripts.
All rights, also for translation, are reserved. The reproduction of this volume or of parts of it only
with approval of the DVS Media GmbH, Düsseldorf.
© DVS Media GmbH, Düsseldorf 2021
Printing: Print Media Group GmbH & Co. KG, Hamm

Welcome
Are you interested in efficient and powerful electron beam welding technology and technological leadership?
Well, you are at one of the best events in your industry.
The International Electron Beam Welding Conference, IEBW 2021, offers a forum at which users and manufacturers
of electron beam welding and processing technology can meet with R&D specialists to share their experience and
learn about the latest developments in the field.
In 2021, due to the COVID-19 pandemic, we are moving the 6th International Electron Beam Welding Conference
into the virtual world, combining pre-recorded video presentations with an exciting innovative and interactive digital
conference format. The IEBW conference will bring together scientists, engineers and technical personnel from
around the globe involved in research, development and application of electron beam welding processes.
The year 2020 will go down in history as the year of many changes. Much has developed differently than planned;
the good remains. The electron beam is certainly one of them. Hardly any technology has been in use so reliably and
reproducibly for decades. Let's discover trends and developments in electron beam applications and advance them
together.
Also, IEBW provides an excellent opportunity for experts not using the electron beam presently but to getting to know
the technical capabilities and advantages of the electron beam. Common fields where the electron beam is used are
for example aircraft and aerospace, automotive and transportation, shipbuilding and off-shore constructions, rail,
nuclear, oil gas and chemical, military and defense, construction and also many outstanding general fabrication yobs
in electronics and medical.
The event is truly one that anyone involved in sophisticated joining challenges should plan to attend.
Many thanks to the International Institute of Welding (IIW), the American Welding Society (AWS) and the German
Welding Society (DVS), moreover to the sponsor FOCUS and last but not least to the ISF of RWTH Aachen University
and Forschungszentrum Jülich for great assistance and support.
We are pleased to welcome you to the 6th International Electron Beam Welding Conference in the digital world.
Enjoy your first digital IEBW meeting!
Wilfried Behr
Technical Chairman of Program Committee
and Chairman of DVS Working Group
International “Electron Beam Welding”
Ernest Levert
Chairmen of Commission C-IV-B
“Electron Beam Processes”
Institute of Welding (IIW)

Table of contents
Preface
Education, Diagnostics and Control Technologies
K. Schulze, Neuberg/DE
Action to address the lack of knowledge of EB technology amongst engineers and others ..................................... 1
S. Gach, S. Olschok, U. Reisgen, Aachen/DE
Process monitoring in electron beam welding by optimizing the in-process sensor technology by means of
backscattered electrons and optical emission .......................................................................................................... 6
Norbert Sieczkiewicz, Lancaster/Cambridge/UK, Colin Ribton, Cambridge/UK, Andrew Kennedy, Lancaster/UK, Yingtao Tian, Lancaster/UK,
Darren Williams, Lancaster/Cambridge/UK
Electron beam characterisation using time series imaging and deep learning ....................................................... 12
Innovations with Electron Beam
M. Muecke, Wöllstadt/DE; D. Kovalchuk, Kyiv/UA
Electron Beam Ion Sources and a novel Electron Beam Source for enhanced Additive Manufacturing ................. 21
T. Tóth, J. Hensel, K. Dilger, Braunschweig/DE
Effect of beam oscillation parameters on the weld geometry and dilution in electron beam welding of
duplex stainless steels with nickel-based filler wire ................................................................................................. 27
T. Krichel, S. Gach, T. Evers, A. Senger, S. Olschok, U. Reisgen, Aachen/DE
Pulsed electron beam spot welding of non-oriented electrical steel sheets ........................................................... 34
Surface Treatment
S. Valkov and P. Petrov, Sofia/BG
Improvement of the surface properties of light metals by electron beam additive technique .................................. 40
M. Ormanova, S. Valkov, P. Petrov, Sofia/BG
Influence of the electron beam parameters on the structure and properties of electron beam surface treated
Ti-6Al-4V alloy .......................................................................................................................................................... 46

Applications
U. Reisgen, S. Olschok, O. Engels, Aachen/DE; M. Sawannia, M. Jarwitz, Stuttgart/DE
Temporally and spatially controlled temperature fields during material processing with the electron beam ........... 50
P. Hollmann, M. Michler, A. Buchwalder, Freiberg/DE; R. Zenker, Mittweida/DE
Electron Beam Welding (EBW) of Additively Manufactured Alloyed Steels ............................................................. 56
T. Pinto, D. Oliver, M. Nunn; Cambridge/UK; E. Warner, G. Jones, P. Wallace; Derby/UK
Electron beam welding for the manufacture of safety critical components
from hot isostatic pressed low alloy steel ................................................................................................................. 64
Special Materials
A. Senger, T. Evers, T. Krichel, S. Olschok, U. Reisgen Aachen/DE; T. Jokisch, Berlin/DE
Electron beam welding of the conventionally casted and directionally
solidified superalloy Alloy-247 LC ............................................................................................................................. 73
T. Jokisch, Berlin/DE; N. Doynov, R. Ossenbrink, V. Michailov, Cottbus/DE; B. Böttger, A. Senger, Aachen/DE
Analysis of temperature field during electron beam welding of hot crack sensitive nickel base alloy ...................... 81
H. Kendziora
Electron beam brazing of fusion reactor heat sinks ................................................................................................. 88
Electron Beam Additive Manufacturing
Baufeld B., Schönfelder S., Löwer T., Gilching/DE
Wire Electron Beam Additive Manufacturing at pro-beam ....................................................................................... 93
List of authors 100

Action to address the lack of knowledge of EB technology amongst
engineers and others
Klaus-Rainer Schulze, Neuberg, Germany
Since 1958 electron beam welding has been recognized as an outstanding technology and used worldwide on an
industrial scale over the course of decades. The number of applications is legendary and well known amongst experts.
But most engineers engaged with industrial welding or product design work are not sufficiently experienced,
or even aware of the possibilities or opportunities that EB technologies offer. So major advantages, both in product
realization, cost saving and manufacturing efficiency are missed. This happens despite the availability of an appreciable
number of publications both for experts [1] and – essentially within the idea illustrated here - for beginners [2].
Therefore, it is now high-time to address this lack of knowledge and to establish a better system for further education.
Some outlines for introducing these changes are given below.
1 Common experiences
Years ago, when I was employed within sales and marketing of EB machines, one day I got a call from industry asking
for a laser machine. After engaging with the caller, he replied: “Oh what? EB that’s yesterday’s technology! Today
we have lasers.” - On other multiple occasions I experienced similar reactions; during the installation of a new
EB machine on a customer’s site, some not directly involved with the project were amazed to learn about the possibilities
of the EB processing. They had never heard about this tool during their studies at university.
To be honest, there are a few universities giving lessons which include electron beam processing. But even those
establishments only provide a basic outline, sometimes no longer than a single chapter. I understand most course
studies are jam-packed. But why is there always time and space for laser topics to a greater extent but not comparably
for EB?
Similarly, throughout the education and qualification for Welding Engineers within the Welding Societies, topics relating
to EB are only lighted touched upon. (I assume, this applies not only in Germany).
Moreover, in the past all the existing education content relating to EB – how much or little, only seem to focus on the
beam in itself and its manipulation as well as to the basics of the welding process but not to the importance of EB
technologies in respect of component design as well as its economic efficiency. In other words, we have to much
better in education, not only for welding specialists but also for designers and production engineers as well.
2 What should be included in education and training, etc. – and to whom
We have to distinguish between project engineers, production planners and EB shop-floor operatives. So, the depth
of subjects taught should be different – and following the extent of the related courses. According to our experiences
we have to specify the courses to three groups of participants:
A. University courses for students
B. Advanced training for engineers
C. Basic education for operators.
But for all groups we recommend a basic content as given in fig. 1
DVS 368 1

Figure 1.
General basic content for education in EB processes and technologies
etail to te rincial oint lite in ill e elaine y te oral reentation rin te conference o et
a etter ireion a fe eale of oeroint lie ere elin toic only are iven in
2
DVS 368

Figure 2.
Minor extract from PowerPoint for the EB welding chapter
can e een te ect atter an core to e covere are
• Importance of EB technologies
• Beam generation, forming and handling
• Welding process and conditions
• Many examples of welded applications
• Custom tailored EB machines
• Automation of mass production parts by EB processing
Further essential topics include
• Part design within EB guidelines
• Welding procedure requirements
• Quality assurance procedures
• Safety precautions
• conoic eciency ot enerally an in etail
DVS 368 3

lto te leon ncle concern elin in vac oter rocere are alo reviee
• rface oication
• EB Drilling and Perforation
• Nonvacuum EB applications.
Naturally, a short comparison between electron beam and laser beam is also reviewed. This comparison is non-partian
an oe not roote or icreit eiter tecnoloy t treat eac attrite realitically
It must be emphasized, that the whole course is a theoretical one – even if some real example parts help to illustrate
certain matters. There is no practical exercise on an EB machine included but visiting any site with EB processing
would be an advantage.
3 Practice of courses
From my own knowledge and practical experience over many years, I can state the following:
A. t niverity level a loc lectre coverin lectre or ill ll te tie for ater an acelor tent
with new and interesting content. EB topic examination is part of the general one for the semester.
B. Because the EB topic is included within the general program of study, the younger students will receive tuition
ic ee rly itin anfactrin rocee o tey ol not overee it later on in ractice
C. vance trainin core for enineer fro intry it ol incle te ae content t en oe ore
time, up to 24 lecture hours over a three-day time frame. This should also include the two hours required for the
examination. Participants to these courses bring a lot of practical experiences with them along, which when
discussed within the course can usually develop into new ideas and solutions for existing problems.
D. aic trainin for oerator ol ave an overvie of te iortance of ein eciency an oter aect
of employing the technology, but will concentrate on aspects concerning machine handling, developing optimum
parameters and welding procedures. Whilst this course is also a theoretical one covering 8 lecture hours,
it i neceary tat it i folloe it intrction on te on acine nly ten ill a certicate e ie
Following this approach, operators will have a better understanding and appreciation of what they are doing
instead of just button pushing.
4 Status quo
A number of people should have the technical experience as well as the skill in teaching to conduct the EB education
mapped out. Unfortunately, only some professors at a few universities are familiar with EB technology. They may
also not have enough time to spend more than two or three lecture hours for this subject. The situation at welding
societies like DVS-SLV is not much better, and in fact their trainers are mostly even less familiar with EB.
A solution to this problem would be to engage an expert as a guest lecturer. We tried this on a number of occasions
over the past years – both at universities and at SLV. Moreover, the same expert can undertake advanced training
core in intry an reearc etalient it eai ecically orientate to teir reireent n all
cae te articiant ave a very oitive feeac o it i ree to rovie real enet
it reect to ro e ave in te eanile create certie ecation ieline [ ic otline
not only te tecnical content of te core t alo all te etail of it eection inclin eaination e rt
core accorin a el in anary at alle articiant cae fro erany an fro
iterlan
Figure 3.
e rt core accorin
4
DVS 368

Unfortunately, due to the corona virus pandemic we were prevented from undertaken following courses. Now we
hope for better times. But this is only half the truth, too few responses from industry to a website announcement
means that scheduling with a fixed date (from SLV) is not economically viable. So, the SLV have revised its position
and will only offer the course without a fixed date, until there are sufficient interested parties. Having collected a
number of them, SLV will then make an arrangement of dates to bring all together. But to make this into a success
story, wider publicity and advertising is necessary – not only through SLV Halle.
Coming to group (C), an equivalent guideline is still in preparation. Content and procedure are defined (as quoted
above) as well as examination questions, now the certification body is asked to finish the approval. But the aspects
for its implementation will be the same as for DVS 1190.
5 Prospects and task setting
As everybody within the EB community knows, this technology has worldwide acceptance over many years, but it
survives through the dedicated activity of a limited group of insiders. However most the active groups do not promote
the technology outwardly, but nearly always faced inwardly towards their own groups. Although we have tried for
many years to get greater publicity for EB technologies, we have recognised that a way to achieve this could be
through better education. Both lectures for students and advanced training for engineers will then enable them to use
EB within their own fields, and to gain real advantages. These new “experts” will then be able to spread and share
their experience and widen so the greater public awareness.
Therefore, maximum success of the education and training programs is the primary goal, and as much as possible
experts should be engaged as lecturers, in any institution. It is not the question of defining a course’s content – this
already exists within the DVS guidelines. Of course, an experienced guest instructor can help to “find one’s feet”.
This support is addressed especially to other SLV besides Halle.
Last but not least, every one of us should promote the training courses and point out to his peers, up to and including
industry management, the announcements on SLV’s website.
6 What else?
Undoubtedly, the content of the lectures must be updated in line with current technological and research developments.
At least within DVS this will be assured by the scheduled review of all documents.
Even though we have discussed this topic based on a German version of education program, it should also be possible
to establish a comparable one in other languages and countries – compare e. g. [3].
Literature
[1] H. Schultz: Elektronenstrahlschweißen – Grundlagen, Maschinen, Anwendungen, DVS Media GmbH,
2017
[2] K.-R. Schulze: Elektronenstrahltechnologien, Band 1 Wissen kompakt, DVS Media GmbH, 2011
[3] K.-R. Schulze: Electron Beam Technologies, Vol. 1e Wissen kompakt, DVS Media GmbH, 2012
[4] Richtlinie DVS 1190, DVS-Lehrgang Fachkraft Elektronenstrahlschweißen, 2019
DVS 368 5

Process monitoring in electron beam welding by optimizing the in-process
sensor technology by means of backscattered electrons and optical
emission
S. Gach, Aachen, S. Olschok, U. Reisgen, Aachen
The demands of the market on manufacturing companies and their products require a time and cost efficient production.
There is an ever-increasing need to make welding production more transparent and to ensure and document
processes and quality in order to be able to meet the requirements of customers as well as laws and regulations. The
extension of sensor technology in electron beam welding can contribute to the achievement of these objectives - by
integrating the detection of discrete wavelength ranges of optical process emissions, optimizing the detection of
backscattered electrons and correlating the measurement signals to process changes and events, irregularities can
be detected in-situ.
The presented investigations include the further development of the detection and analysis of backscattered electrons
and the utilization of optical sensors for the electron beam process. Weldings are performed with the simulation
of typical failure scenarios. The data are evaluated with the aim to find temporal and causal correlations to the
induced defects. It is investigated whether the correlation to welding defects of the combination of optical and conventional
sensor technology is also possible with the optimized backscatter electron sensor technology alone.
In the field of optical sensors the identification of characteristic optical process emissions by spectroscopy and a
selection of suitable photodiodes and band-pass filters based on these results is investigated.
1 Introduction
Process monitoring in electron beam welding is usually limited to recording machine data such as acceleration voltage,
beam current or lens currents and, if necessary, the correction values of the beam device. These enable process
disturbances resulting from beam generation or beam guidance to be detected, but do not provide any information
about a process disturbance from the actual impact zone of the beam on the component. Sporadically, the
detection of the sample or component current and the measurement of the backside passing electron current at full
penetration welds are carried out with the capillary open downwards. While the sample current is primarily relevant
for the determination of the efficiency, the penetrating current allows at least a detection of a continuously opened
capillary. A reliable assignment of signals to welding defects does not exist at present.
2 State of the art
When an electron beam interacts with a material, the kinetic energy of the electrons is converted into thermal energy.
The majority of the energy is transferred to the conduction electrons in the lattice structure, which results in a higher
lattice vibration, which in turn is equivalent to a higher temperature. Although efficiencies >90% are achieved, especially
in deep welding, part of the energy is converted into secondary effects: As a result of the energy transfer to the
conduction electrons, optically visible radiation and thermal radiation are emitted from the material. In addition, X-ray
radiation is released, which is emitted directly by the beam electrons during their deceleration, called X-ray braking
radiation, as well as the emission of the characteristic X-ray radiation, which is emitted by the hit material atoms. [1]
[2] Not all beam electrons participate equally in the energy conversion, some are diffracted in the Coulomb fields and
leave the material with only a small loss of energy. These are called backscattered electrons. During energy transfer,
individual electrons of the lattice compound of the material may receive sufficient energy that they exceed the exit
energy to leave the material compound and leave the material as free electrons. These are called secondary electrons
and can be differentiated from the backscattered electrons by their significantly lower velocity, respectively
energy. In addition to the effects already described, vapourisation of the material occurs, especially in deep welding.
The metal vapour, similar to a PVD process, spreads out in a hemispherical shape over the vapour capillary in a
vacuum and coats everything that is exposed to it. The vapour contains positively charged metal vapour ions. [3][4]
The described side effects all originate from the effective range of the electron beam and can thus be regarded as
information carriers of the welding process. Detected by means of suitable detectors and correlated with associated
process disturbances, they could form a basis for process monitoring systems in the future.
6
DVS 368

3 Experimental procedure and analysis
Backscattered electrons are detected by means of a detector unit consisting of eight individual detector plates, which
are mounted in a ring around the beam path on the chamber ceiling, Figure 1 left. The individual detector plates are
made of graphite and can be aligned orthogonally to the beam spot by means of a cam disk. Electrons hitting the
etector late are ie to ron via a earin reitor nt e voltae ro at te nt t
allows the detection of the incident electrons, Figure 1 (middle). The analogue converter from National Instruments
(Ni9205) provides a cumulative sampling rate of 250kHz.
Figure 1.
Backscatter detector in installed condition (left), circuit of the measurement setup shunt and detector
gap (middle), Row data signal record (inverted) of a backscattered electron measurement (right)
The optical process emission is recorded using the Ocean HDX-XR spectrometer with an integration time of 6ms in
a etectale avelent rane eteen n an n otical re i ie tro a vac feetro
into te orin caer an aline to te roce colliatin len enre cient aralleli e len i
rotecte fro vaoriation y te roce ae y a rotective la an a coaial rotective a o eli
40mnl/min). Comparative measurements using the DIABEAM beam measurement system [5] show no adverse
cane in ea iaeter e to te vole o te caer rere ettle at a tale eiliri -3 mbar.
4 Results
4.1 Backscattered Electrons
Several challenges exist during the acquisition of backscattered and secondary electrons. Firstly, the raw data of the
accattere electron inal o noiy eareent recor ere are neative eection recore a ol
be expected from the detection of backscattered and secondary electrons, but also positive signals are occur, Figure
1 (right). The reason for latter is that positively charged ions hit the detector plates, being ejected by the plasma
jet from the vapour capillary. If positively charged ions meet the detector plate at the same time as negative electron
tey erae eac oter inal n tatitical averae ti lea to a noie of te inal eenin of te
amount of negative and positive particles.
Secondly, metal vapour that emits from the capillary and spreads throughout the vacuum chamber accumulates on
te etector late it increain layer ticne a in a yicalvaoreoition roce i falie
the measurement due to a changed degree of absorption of the detector material. The measurement results stabilise
if a homogeneous vapour deposition layer occurred on the detector surfaces. Ventilation of the vacuum chamber
leads to a change in the absorption conditions as well due to oxidation. Successful, reliable measurements can only
be achieved by deliberately coating the detectors directly before welding, using material of the same kind as being
welded.
eenin on te ele alloy no tainale rface layer i fore n oe alloy layer eel o fro te etector
surfaces. Depending on the alloy, this makes reliable measurement impossible.
Two possibilities are currently being evaluated to improve the noise ratio - on the one hand, increasing the sampling
rate of the analogue converter, which probably reduce the noise through temporal equalisation. For this purpose, the
electron beam welding system will be equipped with a measuring computer with fast analogue inputs, which will
allo te etector late to e canne at to er cannel a clearer teoral ierentiation eteen
positive vapour ions and electrons will be possible. On the other hand, protecting the detector plates via a coaxial
inert a vole o i a econ aroac i tecnie i alreay cceflly in e in te el of laer ea
welding under vacuum (LaVa) to protect the laser optics [6]. It will possibly minimise vaporisation of the detector
late ic avoi te neative eect of layerin an aitionally it i reventin te eavy an lo vaor ion
fro reacin te etector late ile te lit an fat electron ol e only litly aecte ll te analye
DVS 368 7

presented below were carried out on high-alloy steel after prior vapour deposition of the detector plates. The analyses
are based on the mean values of the backscatter electron signals, recorded during a complete weld.
Figure 2.
Backscattered electron distribution on the detector plates during a weld. The signals on a detector plate
are normalised to the total backscatter current and plotted in a spider web diagram (in percent). The
position of the emphasis of the distribution provides information about the capillary.
A local evaluation of the backscatter signals relative to the welding direction allows statements to be made about the
alignment of the capillary. For this purpose, the signals of the individual detectors are shown in the form of a spider
web diagram, Figure 2. The proportion of a detector plate is normalised to the total measured backscattering electron
radiation. Thus, the scales of the diagram are given in percent. A completely point-symmetrical distribution should
terefore relt in for eac etector late f te inivial inal are connecte it a line te relt i a
polygon (blue line) that allows conclusions to be drawn about the distribution of the backscattered electrons. If chan-
e occr in te caillary tee ol alo e reecte in te accatter inal ortoonal to te elin
direction, there should be a symmetrical distribution on the left and on the right. If one side is disproportionately re-
reente ti ol inicate a tiltin of te roce c a col e cae y an ee oet or iilar
One way to express the distribution in two numerical values is to introduce the emphasis of the polygon (red dot). It
allows a direct description of the distribution via its X or Y coordinate. If it is located in the coordinate origin, the distribution
is point-symmetrical, e.g. if there is no welding movement at all. This is also approximately present at slow
welding speeds, Figure 3 above. If it moves orthogonally to the welding direction (Y-Direction), the case of tilting
described above is present. This is clearly visible in the welds with higher welding speed, Figure 3 below. The seams
were welded in only one evacuation-cycle to avoid oxidation of the detector plates. They were directly welded one
next to the other on one specimen (sheet metal dimension 300x200x6, material 1.4301), clamped on one side. As
component distortion occurs, the angle between the beam and the workpiece changes, causing the welds to yield
laterally, visible in the micrographs. Observing the emphasis, the tilting of the specimen is shown in a displacement
in the negative Y-direction. With increasing welding speed, the scattering pattern shifts against the welding direction.
The proportion of forward scattered electrons decreases, while it increases in the opposite direction. Likewise, the
distribution narrows, Figure 3. The emphasis shifts from zero in negative X-direction. This means that with increasing
welding speed, the electron beam interacts primarily on the front half-shell of the capillary wall and electrons are also
reecte ac fro tere ooite to te elin irection
4.2 Optical process emission
Analysis of the optical process emission shows that the wavelength spectrum of an electron beam welding process
is basically the same, regardless of which material it is exposed to, Figure 4. The investigated materials, unalloyed
teel ialloye tainle teel a ell a alini l only o ierence in te inten-
ity of teir eiion ic can e reconie y ierent cont in te ectr e ierent intenitie of te
ierent aterial are not irectly coarale it eac oter a tey ere etecte it ierent aertre to
avoid saturation of the spectrometer.
8
DVS 368

Figure 3.
accatter electron inal itrition at ierent elin ee aterial nery er nit
length constant at 40J/mm – Accelerating voltage 60 kV, sheet metal dimension 300x200x6
DVS 368 9

Figure 4.
Optical emission of an electron beam welding process on the unalloyed steel S355 (blue), high-alloyed
stainless steel 1.4301 (grey) as well as the aluminium alloy Al5083 (orange)
In the ultraviolet range (UV) up to the blue range of the visible spectrum (VIS), there is almost no emission for all
materials. The exception is aluminium, which shows characteristic peaks at individual wavelengths, which can be
assigned to individual alloy elements, beside aluminium these are manganese and magnesium. In the range of the
green light spectrum from approx. 500 nm wavelength, the intensity begins to increase over the visible spectrum in
the direction of red to reach the highest radiation intensity in the near-infrared range (IR) at approx. 900nm. At
n all crve o a inicant ro in intenity i i roaly e to te rotective la or te len aterial,
which is not completely transmissive in this wavelength range.
If the emission spectrum is not considered as a snapshot, but is extended by a time axis in which it is recorded during
a weld, it is possible to infer various events from the interaction zone of the electron beam through changes in the
ectr or eale oenin a caillary on te root ie a occr en elin a ee ecien i reecte
in a drop in the luminous intensity, Figure 5. When the capillary is opened on the root side, a certain portion of the
raiation ae tro onar an i no loner reecte ar i alie to te entire ectr itot
individual wavelengths emerging. During a slope-up of the beam current the capillary builds up into the depth of the
material which is accompanied by a certain time delay. Thus, an increased intensity of the optical signal can always
e een rin te loe ic level o a oon a a tale caillary i fore
coarale eavior can e een it a eect f a a of an oint i oene teie in ti cae fro ero
gap to 0.1 mm followed by 0.2 mm, Figure 6 above, the intensity of the optical signal decreases with the width of the
gap. The spectrometer observes the welding process from behind at an angle of 135° in the X-Y plane during all
tet e eect i ineenent of eter te lit oen toar or aay fro te ectroeter f coer in
(Ø3 mm) are inserted into boreholes in the weld pass at equidistant intervals, a periodically increase of the intensity
appears as soon as the beam hits copper, Figure 6 below. In addition, the characteristic wavelengths of the copper
appear, particularly visible in the blue region of the wavelength spectrum, where the actual EB process is absent.
oarale eect can alo e etecte if te coer aterial i not lace oen to te rface t at a et of
6 mm from the root.
Figure 5.
ectr of a ee ecien ae of itrent teel recore rin elin left
Sketch of the weld conditions with parameters given and top view of the weld (right)
10
DVS 368