Abstracts - ISIM Timisoara

The 7
th
International Conference
Innovative Technologies
for Joining
Advanced Materials
June 19-20, 2014,
Timişoara, Romania
With the support of
Abstracts
National R&D Institute for Welding and Material
Testing – ISIM Timişoara
”Politehnica” University of Timișoara
Romanian Academy for Technical Sciences –
Timişoara Subsidiary
Sponsors
ABSTRACTS
Plenar Session
Enhanced Joint Properties by Magnetic Pulse Crimping with Filler Material
CRAMER Heidi, MUELLER Marc, APPEL Ludwig
Compared to conventional forming joining technics, e.q. mechanical crimping, the magnetic pulse
crimping gives advantages because of a contact-free tooling, a symmetrical coaxial pressure and
forming, as well as a low spring back after forming. Limitations of the general functionality of crimp
joints also obtain for magnetic pulsed crimp joints: Leak-tightness, combined with corrosion
resistance, and a partially Limitation of electrical conductivity (transition resistance). To improve and
to extend the functionality of MP-crimp-joints different filler materials can be used. By environment of
a public research project, adhesives, solder and metal coatings have been applied as filler materials to
MP-crimping. Within the lecture the behavior of the filler materials under the influence of high speed
forming, the suitable operating conditions and achieved joint properties will be described.
Session 1
Analysis of Current State and Integrity Evaluation for the Supply Tank of Generation Unit
6 of Thermal Power Plant Nikola Tesla ”A”, Obrenovac
ARSIĆ Miodrag, BOŠNJAK Srđan, GRABULOV Vencislav, VELJOVIĆ Aleksandar, SAVIĆ Zoran
Stable supply tank, with volume V = 250 m3 and operating pressure p = 1,5 MPa, of generation unit 6
at thermal power plant 'Nikola Tesla A' in Obrenovac, is designed for water-steam working fluid. It
was made of steel Č 1204 as a single-part welded structure with a single wall. Cylindrical tank shell
consists of 8 segments, while torispherical deep bottoms consist of 3 segments. The tank is in the
horizontal position and it lays on 4 supports. There are five manometers installed at the tank for
pressure control, as well as 5 spring-loaded safety valves. In this paper results of non-destructive
tests performed on the tank are presented. Mechanical damages on parent material, up to 1.5 mm
deep, were detected at the outer surface of the cylindrical section of the right bottom (as seen from
the boiler) and on the inner surface of the shell, as well as sporadic pitting corrosion, up to 0.5 mm
deep, and 2 mm misalignment of sheet metals in areas where shell segments are joined. Crack type
linear indications were detected on the surface of welded joints through the use of magnetic particle
testing. Through ultrasonic and radiographic testing it was determined that the homogeneity of
welded joints is satisfactory. Hardness testing was performed on all segments of the tank, and
obtained values were in the range between 118 and 130 HB. Metallographic examination, performed
on specimens of all segments of the tank, showed that microstructure of material is either finegrained or striped ferrite-pearlite. On the basis of test results the repair technology for shell and
bottom segments was made, while on the basis of the analytical calculation of tank strength the
integrity evaluation was carried out for the upcoming period of service, depending on the category of
the vessel.
Analyzing Properties of New Hard Coating Technologies for Increasing the Wear
Resistance
MILUTINOVIC Zlatan, RISTIC Marko, VASOVIC Ivana, PROKOLAB Milan, GLIGORIJEVIC Bojan
The aim of this paper is improving the characteristic of Ventilation mill for grinding coal, which is one
of the main parts of steam power plants in the system that makes a significant influence on the level
of energy efficiency with its work. Working parts of the mill are dominantly exposed to intensive
abrasive and erosive wear during exploitation. For solving the problem of increasing the wear
resistance of transport parts and coal grinding in power plants, we need to investigate the optimal
application of technology in hard coatings by different procedures, and filer materials. Hard coatings
were carried out with cold (plasma and arc treatment) and hot metallization (with concurrent and
subsequent drowning). The filler materials of different chemical composition and properties, based on
Ni (NiCrBSi; NiCrBSiFe; NiCrBSi / WC) and Fe (FeCrCSiMo; FeCrCBSiTi; FeCrCBNiSi) has been used.
The main goal of this paper is to make the selection of optimal metalization procedures, group of filler
materials and metalization technology definition, based on the results of structural and mechanical
properties of samples, experimental model hardfacing. These were investigations of its structure,
measurement and distribution of hardness in the samples, tribology characteristic samples with hard
coatings. Based on the results of these tests, the filler materials and procedures for applying hard
coatings were selected, which would be applied in the revitalization of parts in transport and at coal
grinding.
Influence of Slag-Flux Mixture on the Properties of Welded Joints
DOBRÁNSZKY János, NÉMETH Levente, BICZÓ Csaba
Submerged arc welding (SAW) is one of the most versatile welding processes. All steel grades, from
non- to high alloyed, including Ni-based alloys, can be welded with a combination of various
techniques. The process became common worldwide for these properties, and shows a high degree of
growth in countries with significant heavy industry. In the process, a large amount of slag is formed
from the flux, which is treated as waste. The slag contains non-renewable raw materials, minerals.
The mining, processing represents a significant environmental impact. Short life cycle of products
from high-energy input is not compatible with the eco-thinking. That is why recycling of these
materials is highly appropriate from environmental and economical aspects. The paper presents a
method in which the slag can be used as a valuable flux component with significant cost- and waste
reduction by ensuring no loss of mechanical properties.
Analysis of the Quality of the Weld Metal Obtained with Alloyed Flux-Cored Wire
BAJIC Nikola, RAKIN Marko, VELJIĆ Darko, MRDAK Mihailo, STOJADINOVIC Slobodan, PEKEZ Jasmina
The main aim of this paper is to assess the quality of newly produced, alloyed flux-cored wire with
increased thickness of the steel cover compared to traditional according to ASTM, AWS A5.28 E110CG, EN ISO 18276-A-T 69 6 Mn2.5Ni M M 3 H5 standard, alloyed with Ni and Mo, and designed for
welding of fine-grained HSLA steel. Flux-cored wire was produced on a pilot production line that
allows calibration of steel band of higher thickness and production of flux-cored wire. Quality
assessment of the alloyed flux-cored wire was based on the analysis of the results of tests of
mechanical properties and microstructure mainly of the weld metal. Variation of chemical composition
and microstructure were analyzed along weld metal (for each welding pass) and heat affected zone
(HAZ) using SEM and EDS. Based on the results of the quality assessment of flux-cored wire, the
conclusions about the feasibility of industrial application of selected metallurgical grade of flux-cored
wire designed for welding of fine-grain HSLA steel were presented.
Session 2
3D Simulation of Stress-Strain State of Plasma Arc Surfacing by CAD/CAE Software
Sysweld
DIMITROVA Rayna, NEDELCHEV Alexander, NIKOLOV Antonio
The deformation process during the plasma arc surfacing is analyzed by CAD/CAE software SysWeld
under Visual Environment using 3D simulation. The aim of simulation is visualization of a temperature
field and a stress-strain state distribution as results of surfacing under typical technological
parameters of plasma arc processing which could be used for education.
Ways of Numerical Prediction of Austenitic Grain Size in Heat-Affected Zone of Welds
MORAVEC Jaromír, BRADÁČ Josef, NOVÁKOVÁ Iva
In the present time there is a clear effort to achieve the most exact mathematical description of the
behaviour of “Hi-tech” materials when exposed to temperature and stress loading. Besides the
common numerically predicted values such as temperature, deformation and stress fields, or as the
case may be structure changes during phase transformations, demands for prediction of the austenitic
grain size in HAZ of welds become more and more frequent. That is why the present submission deals
with the analysis of the determination of the grain size and grain growth kinetics of HR3C single-phase
austenitic steel using the Monte Carlo Potts method. The procedure of obtaining the input data for
numerical simulations will be demonstrated on HR3C steel, including the determination of grain
growth kinetics and definition of all the parameters needed for a computational model. Results from
the numerical simulation in Sysweld program will be then compared against the real experiment for a
multi-layered weld made on HR3C tube.
Stress State Arround the Imperfections in Welded Joints
JOVIČIĆ Radomir, SEDMAK Simon, TATIĆ Uroš, LUKIĆ Uroš, PROKIĆ – CVETKOVIĆ Radica,
POPOVIĆ Olivera, JOVIČIĆ Katarina
Welded joints because of their geometry can cause a local increase of stress. In the presence of
imperfections in welded joints the local stress additionaly increases and can lead to the formation of
cracks. In this paper are presented cracks that were detected in the welded joint during testing of
pressure equipment in service and the stress state around imperfection was analyzed by finite
element method. It was concluded that even the imperfections that are acceptable for the highest
level of quality, according to standard EN ISO 5817, causes significantly higher local stress than the
stress predicted during design of structure.
Numerical Modeling and Initial Fatigue Life Estimations of Welded Structural Components
VASOVIC Ivana, RISTIC Marko, RISTIC Slavica, MAKSIMOVIC Mirko, STAMENKOVIC Dragi
Numerical simulations are powerful tool for analyzing and research in domain of mechanical
constructions. In welded joints is very important to determine residual stresses and temperature
distribution in sample, apropos, element of construction. For welded construction that are in
exploitation is not possible doing experiments, so numerical simulations can give the required results
and overview of stress state, residual stresses, critical areas, displacement, temperature distribution
and other data is needed for analyzing and improvement of constructions or parts of constructions.
This analysis includes finite element model for the thermal and mechanical welding simulation.
Welding simulation was considered as a sequential coupled thermo-mechanical analysis. The residual
stress distribution and magnitude in axial direction was obtained. Numerical methods are also used in
order to predict the crack of specimen. In this paper is obtained good agreement of results between
experiment and numerical simulations.
Repair Weld Simulation of Austenitic Steel Pipe
BÉZI Zoltán, SZÁVAI Szabolcs
In this study the repair weld simulation of an austenitic steel pipe is performed to measure the
residual stresses caused by the welding. The simulation consists of three work tasks. First the girth
welding of the pipe is performed on simplified geometries to decrease the calculation time. The next
work task is the simulation of the machining of the repair weld excavation, performed in one
simulation step. The last task is the simulation of the repair welding. Residual stress measurements
are performed on weld repair to provide validation of the simulation performed on the model.
Application of Numerical Simulations at Welding Multilayer Welds from the Material
X22CrMoV12-2
MORAVEC Jaromír, SLOVÁČEK Marek
Heat-resisting martensitic steel X22CrMoV12-1 is suitable to be used particularly for steam turbine
components (e.g. blades or action wheels of steam turbines) and as parts of airplanes structural
devices. The aim of this paper is to show how numerical simulations can help to optimize welding
procedure of this very hardly weldable material. On the real multilayer weld will be described how to
arrange whole experiment in order to obtain not only relevant input data but also verification data. As
a result it will be possible to set up the computational model for this type of steel and consequently to
use it for simulation computations of welding and heat treatment of real structure components.
Development of a new generation of welding simulators for education and training.
ENGH Erik
During the years a number of different simulators have been developed for the welding community.
These simulators have been targeted to different user groups and different technical level of the
group itself. The technological quality has mostly been on a professional level, although the user
friendliness, we must admit, may have a wide interpretation of the word “friendliness”.
The use of mobile devices, pads and so forth, with other interface methods than the keyboard, that
has appeared over the last years have given us new opportunities to define user interfaces that are
completely different from what was possible before.
This paper will discuss a work in progress for a simulation project development related to education
and training, in two different projects, IWSD (Leonardo da Vinci project) and Green Weld (EEA Grant
project), currently running in Romania and in Bulgaria.
Session 3
Pulsed LASER-(micro)TIG Welding of Automotive Zn Coated Advanced High Strength
Steels Thin Sheets in Overlap Configuration
BÎRDEANU Aurel – Valentin
The wider implementation into automotive sector of new materials categorized as Advanced High
Strength Steels (AHSS) in order to reduce costs and weight require the development of appropriate
joining technologies. The paper presents the results of applying of a new hybrid welding process, i.e.
Pulsed LASER-(micro)TIG, for realizing overlap joints for Zn-coated AHSS materials.
The statistical influence of main hybrid welding process parameters was investigated by means of
factorial experimental design and weighted against the shear strength results of the realized joints.
The influence of laser pulse peak power, the average welding TIG current and the joint gap was
investigated for three types of Zn coated AHSS with different thicknesses.
The results revealed that sane joints could be obtained with the new welding process and that the
new process is fit to be applied for these materials.
Each material did behave different in respect to the investigated process parameters and the results
did reveal rather strong interaction between the influence factors (IF), however the joint gap does
play an important role in respect to the maximum shear strength of the joint, which could be
correlated to the specifics of the laser beam welding of Zn coated steels. The strong interaction
between the studied IF imply further study of the new process by including other process parameters.
Joining of C/SiC Materials by Spark Plasma Sintering
TSAKIRIS Violeta, KAPPEL Wilhelm, TALPEANU Dorinel, ALBU Florentina, PATROI Delia, MARINESCU
Virgil
High density graphite and silicon carbide powder (α - phase) were used to obtain joints by Spark
Plasma Sintering (SPS) technique. The joining of C/SiC was performed both by direct bonding (DB)
and with the aid of a ceramic powder mixture (SiC+5%wt.B4C) as intermediary joining material. The
joints were performed in vacuum at 1900oC under 30 MPa with a dwell time of 3 minutes. The
interface structures of the obtained joints were characterized from the structural and mechanical point
of view. XRD analysis of both joints have shown only the presence of crystalline phases of SiC and C
while the crystalline phase of B4C was not detected due to its low content (5 wt.%) with a higher
degree of amorphization of 9.1% for the junction with interlayer than that of the corresponding
junction obtained by DB (5.5%). Interface compositional analyses and SEM images have shown that
the process of diffusion bonding was the mechanism both for joining by DB and with a SiC+5wt%B4C
interlayer. The Vickers microhardness and Young Modulus values measured by nanoindentation
evidenciated a strong increase of HV values (11 – 14 GPa) at interface for the junction with SiC+B4C
intermediate layer and, as expected, the highest stiffness (180-197 GPa).
Lap Joint Laser Welding of Austenitic Stainless Steel Thin Sheets
STANCIU Elena-Manuela, PASCU Alexandru, ROATĂ Ionuț-Claudiu
This paper investigates the laser welding of AISI 304 stainless steel thin sheets. For the experimental
procedure a 3,3 kW Nd:Yag laser was used. Nine samples were realised during this study and the
influence of the process parameters on to the geometry and microstructure of the weld bead is
analysed. The best result in case of 0,5 mm stainless steel laser welding are obtained by using a
density power in the range of 700-850 kW/cm2 associated with a minimum spot diameter of 0,4 mm.
The weld bead compositional content was determined by an X ray dispersive field analyses. A
decreasing of Mn and Si content into the weld zone was produced mainly by the burning and
vaporization effects during the laser welding. Good tensile behaviour of the joints was obtained at all
samples with fracture was produced at 600 MPa.
Research Regarding the Manufacture of Pipelines Through Automatic Tandem MAG
Welding on Generators
TOMA Cosmin, IOVANAS Radu, IOVANAS Daniela Maria
The manufacture of pipelines is a complex technological process starting with laminates supply, joints
cutting-processing, rolling, welding, calibration, control, packing, delivery. As a rule, the technological
welding process is achieved by welding on generators through MAG and submerged arc welding,
procedures which generally take place completely automatically, affecting the quality and cost of
products. Beside a series of advantages, submerged arc welding also has disadvantages; it does not
eliminate the operator’s intervention and implies some high linear energies with implications on the
mechanical-metallurgical characteristics of the welded joints.
In this paper we present the preliminary results of the experiments which have been carried out on
welded joints on X52 steel plate, g = 12 mm, through classical MAG welding, with one wire - filler
material on the first layer, and the filling beads through tandem MAG welding, with two wires. We
should mention that the plates had a V(30°) joint and the welding was executed unilaterally,
horizontally, the wire - filler material being of the same quality G42 4 M G3 SI1 ( EN ISO 14341) and
diameter (1.2 mm), and EN ISO 14175 protection gas. The entire technological welding process was
carried out in laboratory conditions, fully robotized, using a QIROX-315 welding robot fitted with
QUINTO-GLC 603-type tandem MAG welding installations, owned by ICDT-PRO-DD C12 “Advanced
welding eco-technologies”, belonging to Transylvania University of Braşov.
Lead-Free Alloys for Ecological Solders Manufacturing
KOSTOV Ana, MILOSAVLJEVIC Aleksandra, TODOROVIC Radisa, GOMIDZELOVIC Lidija
Although the European Union’s directive about environment protection as WEEE and RoHS have been
carried out in 2003, led solders are still in used in Serbia. In the aim to respect the European and
world directives and laws, it is necessary to reduce a quantity of toxic element and to establish lead
and cadmium free solders in production. In this paper it was presented lead-free alloys, which are
used for ecological solders manufacturing and various applications.
Composite Rods for Brazing
BINCHICIU Emilia, FLESER Traian, VOICULESCU Ionelia
The paper presents research conducted for the development of precursors and wrapped rods for
brazing, that deposit, through melting, two different alloys, with respect to the level of silver alloying
and the melting temperature.
The alloy with the high silver content is introduced under the form of powder, in the coating of the
brazing rods, in a participation proportion that assures a buffer layer, with advance proprieties of
diffusion in the base metal and in the core alloy of the coated rod.
The participation ratio of the silver rich powder alloy is established within the following limits 8-12%,
depending on their melting point, the grinding degree and mixing with the deoxidizer coat.
The development of the precursors was made by homogeneous melting and spraying on a oblique
plan, the grains obtained were grounded, the grist obtained is considered optimum to be introduced in
the coating mixture after it successfully passed through a sieve with a mesh of 0.1 mm.
The alloyed precursors with 45% silver, grounded between the above mentioned limits, were
introduced in the deoxidizer coat mixture of the bare rods, type Ag30, according to SR EN 1044/1999.
The resulted mixture was used to manufacture experimental lots of covered rods for brazing, which
were used for testing, in order to achieve highly important joints.
The melting temperature of the precursors was established through micro-alloying so that it will be
10-150C higher than that of the deoxidizer coat, which in turn has a lower melting temperature, by 5660˚C, than the melting temperature of the core alloy.
The deoxidizer coat is usually fluoroboric type, conforming to SR EN 1045/2001.
Representative joints made with the new experimental rods, after testing, presented results consistent
with the requirements, which allowed the authors to appreciate this method as appropriate for cost
reduction with brazing materials in the use of composite coated rods.
Nanostructured Materials for Cladding by Welding
TIHANOV-TĂNĂSACHE Daniel, FLOREA Carmen, BINCHICIU Emilia, GEANTA Victor
The rigorous stress conditions of active surfaces, from the components of magmatic rock processing
equipment of surface pits, required finding new materials and system processes that achieve a major
impact on wear processes, in the sense of decreasing them. Conducted research with classic cladding
by welding materials showed a high importance of the chromium carbides in deposits, in the fight
against wear. From manufacturing considerations, the participation of chromium carbides in the
deposits made with traditional welding materials is 35%, which required finding new ways to obtain
superior performances.
The group of authors considered the nanostructure method to be convenient, hence of finishing the
deposition structure, by introducing in the cladding, welding material composition centers of
crystallization with colloidal size and superior temperatures, compared to the molten through welding
bath temperatures. In order to achieve a new generation of cladding by welding materials, we
proceeded to develop, on the above mentioned principle, rods that deposit by welding alloys like Fe20%Cr-4%W-1%Ti, nanostructure with melted tungsten carbides and colloidal grinded. The rods thus
obtained were used for cladding active surfaces of general purpose extraction and processing
machines for basaltic rocks, to achieve highways.
Results obtained confirm theoretical assumptions, which led to the implementation of new products in
industrial production.
New Ecological Technique for Soldering of Metallic Materials
COJOCARU Radu, BOȚILĂ Lia, VERBIȚCHI Victor, CIUCĂ Cristian
The performances, qualities and extraordinary development potential of the friction stir welding
process (FSW) are well known in the world, both in the scientific and industrial areas. The innovative
technical developments, based on the principle of the FSW process, conducted at ISIM Timisoara, as
well as the results obtained so far have put the foundation for initiating a new method for bonding of
materials, namely friction stir soldering. The principle of the new soldering process is based on
important features of the FSW process. The paper presents the results of a program of experiments,
which had as its main objective checking whether the new proposed soldering process is viable and
applicable. Positive results were obtained by the soldering tests of copper (Cu99), brass (CuZn39Pb2)
and steel (S235). Promoting this new environmentally friendly process of soldering is beneficial,
because it complies with the current trends worldwide regarding both the environment and health.
Session 4
Methodology for Reparation of Damaged Sleeves and Welded Shield Sections of Guide
Vanes at Hydropower Plant DJERDAP 1
ARSIĆ Miodrag, VISTAĆ Brane, BOŠNJAK Srđan, GRABULOV Vencislav, SAVIĆ Zoran
Vertical Kaplan turbines, manufactured in Russia and with nominal power of 200 MW, have been
installed in 6 hydroelectric generating units at ’Djerdap 1’. During the refurbishment of hydropower
plant experimental non-destructive tests were performed in order to determine the state of turbine
components. During the course of testing damage was detected at sleeves and welded shields of
guide vanes, which occurred as a consequence of turbine shaft vibrations. 1782 mm long guide vane
sleeves were made of cast steel 25L (GOST standard), 260 mm long sleeve was made of forged steel
St 25 (GOST standard), while welded shields of guide vanes were made of austenitic steel 08X18H10T
(GOST standard). Results of experimental tests and methodology for reparation of damaged surfaces
of sleeves and welded shields of guide vanes are presented in this paper. It was necessary, due to the
structural solution used for the design of guide vanes and their function during service, to define a
large number of details, carefully reconsider them and carry out all activities with extreme care in
order to enable the safe operation and continuous use of vanes through the use of reparation
methodology for welding/surface welding of sleeves and welded shields. Overlooking, underestimation
or incorrect perception of important details could cause significant problems during turbine operation.
Research on argon protection when using WIG welding
ŢUNEA Daniel, BURCĂ Mircea
The paper presents the theoretical bases of gas flow, as drowned jets, the device used for viewing
the pure gas cone (argon) using a smoke screen infused on the edge of the argon jet and then the
results of researches carried out on four sizes of nozzles often used in TIG welding. On each type of
nozzle the argon flow parameter was varied and the height of the cone of pure argon was
photographed and measured. The paper ends with the mathematical correlations that allow us to
maximize the height of pure cone argon in relation to its flow.
Reconditioning by Welding of Rims Manufactured from Nonferrous Alloys
BULARDA Nicoleta, HEPUT Teodor
At present, in the automotive industry, the trend on the world plane is to fit on the wheels with rims
made from nonferrous alloys, based on aluminum, magnesium or titanium. These rims have the
advantage that they are lighter than the same rims made from steel, reducing the unsprung mass of
the vehicle, and increasing the vehicle performances, that lead to the better handling, the faster
braking and the better acceleration. Also, by using the rims made from nonferrous alloys, the
increasing of the fuel consumption efficiency and the reducing of the carbon monoxide (CO) emission
are obtained.
During the traffic, the wheels (rim + tyre) can be subjected to accidental collisions, such as the impact
with the pavement, leading to damages of the rims, which must be reconditioned.
The paper presents the results of structural examinations and mechanical tests, made on car rims
made from nonferrous alloys, degraded and reconditioned by specific welding technologies.
The structural and mechanical characteristics determined in the zones reconditioned by welding are at
the level of the base metals used to made the investigated rims, that confirm the adequate quality of
them, and a low risc to cracking.
Estimating the Reliability for Asphalt Milling Machines Teeth Manufactured by Claddings
Processes
IOVANAS Razvan Florin, IOVANAS Daniela Maria, DUMITRASCU Adela-Eliza
The issues from the last decades related to the crisis of natural resources, raw materials, equipment,
energy etc., gave rise to a new concept, namely sustainable development.
The theory of sustainable development focuses on the development of quality products to provide
trust and confidence, so as reliable.
On this line the paper presents an approach on assessing the reliability and non-reliability of the
milling teeth for asphalt machines classic manufactured and those manufactured by welding load,
which give them self wear protection systems and self-lock at rotation.
So in this sense there are presented comparative estimates regarding to the operating lifetime of the
four batches of milling teeth for asphalt, 41Cr4 mark steel (EN 10083-1) the classic version and 3
groups of teeth load by weld on their working surface(wear) by different welding methods, namely:
WIG - with filler material type tubular wire FILEUR DUR 606B, WIG – filler material with tubular type
VT2, 5CrTiD rods, and MIG/MAG (CMT), the tubular wire filler material type FILEUR DUR.
So, asphalt milling machines were stripped with 4 groups of teeth in order to track the behaviour
during exploitation of each batch.
Assuming that the product specifications properly respond customers' requirements, the level of
reliability can be measured accurately by the fraction of delivered units that meet the specifications.
On this line for estimating the reliability the Monte Carlo simulation method was used, which is
suitable for analyzing the products that are designed to provide superior quality.
The Influence of Vibration on the Microstructure of the Wear-Resistant Layer Made with
the Welding Wire MSG-6-GZ-C-60G
LUCA Mihai Alexandru, PISU MACHEDON Teodor
In the production of steel parts exigent of high durability to abrasive wear at high temperatures and /
or corrosive environment, the method is used for the deposition welding with the addition material
MSG-6-GZ-C-60G. With this material layer it is made of 55-60 HRC hardness, corrosion and wear
resistant, with properties that are kept up to temperatures of 500 ⁰C. There can be manufactured new
parts (pressure casting forms, components for dies, molds, etc.), or dynamically and abrasion-torn
reconditioned parts may be required.
Deposits have been made with wear-resistant layer on the steel 42CrMo4, with and without the
generation of vibration during welding. For the samples swing, a device was used with an
electrodynamic exciter to generate vibrations with frequencies up to 20 kHz. Vibration tests were
performed at a frequency of 50 Hz, because the frequency can be applied in industrial conditions, by
means of excitation of electromagnetic or vibration driven motor. There have been registered
horizontal and vertical accelerations which lead to changes in the conditions of crystallisation of the
melt, respectively the formation of a microstructure with superior features.
Microstructures and hardness recorded on specimens welded with and without vibration are
comparatively presented. Micrographs which were made demonstrate the favourable influence of the
vibration on the quality of the deposited layer and the base material. Whith the vibration with
accelerations of ax = 55 m/s2 and az = 70 m/s2 resulted: much lower deformation of the base
material, HAZ - a lower content of residual austenite, in the TZ there was a great interlock of the two
materials, in the deposited material the dendritic crystals strongly fragmented and the grain was
finished.
Corrective Solutions for the Shaft with Flange Used for Fixing the Blade on a 5 kW Wind
Turbine to Withstand Extreme Weather Conditions
BĂDĂRĂU Rodica, MILOŞ Teodor, BORDEAŞU Ilare, BEJ Adrian
The paper presents a case study on the original solution of a flange shaft as part of the root area of a
5 kW wind turbine blade. There were analyzed the causes that led to the shaft breakage under wind
loadings in extreme weather conditions, and consequently technical solutions have been searched in
order to improve the shaft design making it more reliable as mechanical strength at extreme wind
loadings. The flange shaft is a welded subassembly that keeps the blades attached to the rotor hub.
The first part of the paper consists in an analysis referring the loading status, the materials used for
blade manufacturing, the identification of critical areas where the breaking was initiated and also the
causes for which the materials assumed and specified in the technical design and manufacturing
technology failed under loading at wind gusts of about 30 m/sec. Based on this preliminary analysis,
the second part of the paper presents the technical solutions which were considered in reference to
the materials and the improved design concept aiming to provide the right mechanical strength
necessary to withstand specific wind loadings in extreme weather conditions.
Cold Metal Transfer Welding of Aluminum 5456 Thin Sheets
ROATA Ionut-Claudiu, PASCU Alexandru, STANCIU Elena-Manuela, POP Mihai Alin
This study aims to determine the optimal parameters for cold metal transfer MIG welding of aluminum
thin sheets. Starting from this perspective, the filler material of AlMg5 full wire type and a synergic
regime of welding with a low linear energy were used. The characterization of welded joints was
achieved by macro – microscopic analyses, mechanical tests (microhardness and tensile) aiming to
lower the thermo - mechanically affected zone. The results highlight the major influence of the
welding parameters over the weld bead geometry and tensile behaviour of the joint.
Refining the Welding Technique for Nuclear Fuel Elements at INR Pitesti
TRUTA Calin-Stefan, DEACONU Viorel, GONDAC Cristian
Sealing of nuclear fuel material inside the fuel element clad must create a leak-tight "safety barrier" to
prevent the release of radioactive products to environment. High quality welds are mandatory to
withstand harsh conditions (radiation, pressure, temperature, corrosion) making possible the safe
operation of nuclear reactors. The joint design, material selection and welding technique must be
combined by smartly balancing possible technological options to yield the best attainable quality for
the intended purpose; these choices are discussed in the paper.
For thin-walled clad to end-plug welding, heat flow pattern as determined by joint design and fitting
accuracy proved to be crucial for the fusion boundary shape and moreover for the success rate in
automate welding. Consequently, Finite Element Analysis of the transient thermal field during welding
was performed, in order to determine the best compromise with reasonable machining precision for
parts. The main features of the developed thermal model and some results illustrating its good
predictions vs. actual welds are also presented.
Helium-shielded pulsed welding was initially preferred to minimize HAZ, distortion and porosity but
unfortunately important cast-to-cast variation in penetration was observed with Inconel-600 plugs,
due to Marangoni effect. Extensive work was done to overcome this, mainly through variation of
pulsing and of the shielding gas; depth-to-width ratio can be noticeably improved with no material
addition.
Out of welding classic cladding materials, studies were initiated at INR on joining oxide-dispersion
strengthened (ODS) alloys and specialty austenitic formulations (e.g. 15/15Ti) since they are
candidate materials of great interest for the next generation of nuclear reactors.
Session 5
Determination of some Mechanical Properties of Welded Reinforcing Steel with Selfshielded Wires by Vibration Tests
BERETEU Liviu, BURCĂ Mircea, MOISA Raul, SIMOIU Dorin, DRĂGĂNESCU Gheorghe, PAVEL Ştefănel,
NEŞ Cristian
Reinforced concrete is a material formed by pouring concrete over reinforcement steel bars and wires
and sometimes by a polymer that turns by drying in a hard and rigid composite. Welding of steel
reinforcement concrete is a relatively difficult operation and with a large amount of work, given by the
large number of welds that are needed and when this work is make in site conditions. The most
common method of steel reinforcement welding is manual welding with coated electrode. The major
disadvantage of this process is low productivity in welding effects on execution time, and the cost of
welding. An alternative to manual welding with coated electrode for steel reinforcement welding on
site is the welding process with self-shielded tubular wires.
The aim of this paper is to determine the mechanical properties of welded reinforcing steel PC 52 with
self-shielded wires, using a vibroacustic technique. To validate this method, the results obtained by
vibroacoustic signal processing are compared with those determined by the tensile stresses of the
same samples.
The Effect of Water Pressure Variation on Cut Surfaces Quality during Abrasive Waterjet
Cutting of Austenitic Steels
PERIANU Ion Aurel, MITELEA Ion, ŞERBAN Viorel Aurel
In this paper research elements regarding the effect of water pressure variation on cut surfaces
quality are presented in the field of abrasive water jet cutting of materials hard to process by
machining such as austenitic stainless steels, in this case with a thickness of 20 mm. Selection of the
optimal cutting process based on technical and economic criteria takes into consideration the type and
thickness of the targeted material and also the physical and geometrical quality requirements.
The present paper contains experimental research results regarding abrasive water jet cutting of
austenitic stainless steel EN 1.4306 (ASTM 304 L) at different values of water pressure. The abrasive
material used is Garnet with particle granulation 80 Mesh. By making roughness measurements and
hardness examinations of the cut surface an evaluation will be made of the surface quality defining
the optimal pressure values.
Study Regarding the Cavitation Erosion Behaviour and Residual Stresses of Impact
Resistant Hardfacing Materials
SECOSAN Evelina Roxana, CIUBOTARIU Relu Costel, COJOCARU Vasile, FRUNZAVERDE Doina,
CAMPIAN Constantin Viorel
In the last twenty years the cavitation erosion resistance of various welded materials was subject of
extensive studies. Despite these, the research field is still opened. The multitude of materials used for
the fabrication of hydraulic equipment and the variety of the operating conditions in hydropower units
require adapted solutions. This paper presents the investigations made on welded overlays realized
using an impact resistant hardfacing alloy, recommended by manufacturers for protection against
cavitation erosion.
The material was characterized by metallographic investigations (light microscopy, scanning electron
microscopy and EDX–analyse), Vickers micro hardness tests, residual stresses measurements carried
out by the hole-drilling strain-gage method and cavitation erosion tests using the vibratory method.
The results of the cavitation erosion tests were correlated to the behaviour of the martensitic stainless
steel 1.4313 (grade X3CrNiMo13-4 corresponding to EN 10088-3) frequently used for the
manufacturing of the hydraulic turbine components.
The Effect of Silicon Content into the Aluminum Matrix on the Microstructure and
Mechanical Properties of TIG/FSW Welds
GHEORGHIU Diana Antonia, TOMA Stefan Lucian, BEJINARIU Costica, BERNEVIG Mihai
Aluminum silicon alloys, the 4xxx group of the aluminum alloys, are mostly processed into cast parts.
As for other cast designated alloys, their weldability is often considered as an unimportant feature.
The interest, if any, is almost completely related to the repair welding.
The present work analyses how silicon particle dimensions, which depends mostly on the silicon
content into the metallic matrix, affects the weld properties. Also it is revealed the HAZ metallographic
aspect for two frequently welding processes used on aluminum alloys, TIG and FSW. Friction welds
resistance is better than that of the TIG welds, associated with a lack of symmetry (retreating side
versus advancing side).
Silicon particles diminish their dimensions for hypo eutectic or eutectic concentrations; for hyper
eutectic compositions the effect has an almost unimportant effect.
Evaluation of abrasive wear resistance of Fe-Cr-C hardfacing alloys deposited on active
components of the agricultural components
DOBRA Ramona Monica, FARBAS Nicolae, PASCU Doru Romulus
In most of the engineering applications, such as mining, agriculture, metallurgy, the equipments fail
due to abrasive wear. Hardfacing is one of the most economical and most widely used methods of
improving surface characteristics of engineering equipments (wear, corrosion) without changing the
bulk properties of the components.
Fe-Cr-C hardfacing alloys are well known for their excellent performances under severe wear
conditions. The wear behaviour of hardfacing alloys depends on their chemical composition, on the
microstructure obtained after welding, of the welding technology, respectively the welding parameters
which strongly influence, for example, the dilution with the base material or formation of precipitated
hard phases.
The aim of this study was to characterize the microstructure of Fe-Cr-C hardfacing alloys and to
investigate their abrasive wear behaviour. The research has been carried out using four types of FeCr-C hardfacing alloys (8, 12, 16 and 20 % Cr). The alloys were deposited on the low-carbon steel
S355 JR by manual arc welding method. The abrasion wear testing was carried out using the Taber
Rotary Abraser Equipment. The microstructure characterization and surface analysis were performed
using optical microscopy and HV 10 hardness tests.
Characterization of Plasma Cut Surfaces with Water Bed Welding Metallic Materials
MACHEDON PISU Teodor, LUCA Mihai, MACHEDON PISU Elena
The purpose of this paper is to analyze the quality of cut surfaces with plasma in the free atmosphere
and in the water bed of metallic materials being welded.
This process leads to savings in labor, materials, supplies and other costs of production, having as
purpose the decrease in the cost of cutting the work piece and reducing deformation and heat
affected zone in the piece cut, providing alternatives to processing cutting.
It was designed and built a device cutting water bed that has been proven. In the macroscopic
analysis reveals that the cutting in water bed slag layer is lower. After microhardness measurements
(base material, heat affected zone, the cut) it is found that the cutting in water bed cut occurs on the
surface microhardness increased by 36% .
Alternate Design Solutions for reduced Stress Concentration Factor (SCF) T Joints of
Circular Hollow Structures
DIMA Gabriel, MACHEDON - PISU Teodor, BALCU Ion
Design for fatigue of lightweight welded tubular structures is a significant concern of development
teams. Based on practical design experience, alternate T joint design to usual Circular Hollow
Structures (CHS) T joins are proposed. Proposed designs employ formed members within relevant
dimensions range. A method based on finite element analysis including weld modelling was used, with
analytical calculation of weld toe stress. Stress concentration factors (SCF) are calculated for all
proposed designs for all typical load cases. Best placement and dimensions of formed members is
given, together with design recommendations.
Session 6
The Increasing of Corrosion Resistance of Low Alloy Carbon Steels Used in Petroleum
Industry through Coating with Alloys Based On Fe-Ni-Cr by Thermal Spray
TOMA Stefan Lucian, PENEOASU Margareta, BEJINARIU C., GHEORGHIU Diana Antonia, EVA Lucian,
TOMA Bogdan
The main objective of this paper is to evaluate the mechanical properties, chemical and corrosion
resistance of four types of metallic coatings: FeCr, FeCoCr, and FeCoCrNi, FeCrNi sprayed through
thermal spraying in electric arc on an anchor substrate type 95Ni5Al or 78.3Ni20Cr1. 4Si0.3Fe. The
five layers tested were deposited on carbon steel support low alloyed and the obtained results have
provided a picture regarding the possibilities of using of the deposits. Because these types of alloys
are used to increase the wear resistance of tools, it is very important to know their behaviour is saline
environment, because the contributions brought by this paper would increase the applicability domain
of these materials (could be used to recondition by thermal spraying the tools used in naval and
petroleum industry). The researches of the obtained deposits have been carried out through several
methods to screen their performance. Therefore, there have been done investigations on the
microstructural morphology of the deposit, by optical microscopy (OM) and scanning electron
microscopy (SEM). The OM and SEM results have sought to determine the degree of uniformity of the
deposits and the amount of pores and oxides in layer. The physical properties of coatings were also
evaluated by adhesion and porosity quantification. The corrosion resistance was evaluated by
exposing samples in saline fog chamber. The corrosion products formed on the surface layers were
investigated by scanning electron microscopy (SEM) analysis of the SEM. The intermediate alloy
78.3Ni20Cr1.4Si0.3Fe used as anchoring layer allowed the reducing of the pores and micro cracks
frequently found in the ordinary 95Ni5Al alloy. It has been observed that the deposits based on
NiCrCo are good enough to be used as an efficient coating of carbon steel in aggressive marine
environments.
Weldability of Magnesium and Aluminum Alloys using Nd-Yag Laser
GEAMĂN Virgil, RADOMIR Irinel, POP Mihai Alin
Weldability of magnesium alloy to aluminum alloy in laser weld bonded (LWB) joints are investigated.
Results showed that magnesium/aluminum could be easily joined by LWB under proper technological
parameters. The weld is characterized by complex vortex flow at the weld pool and there exist
intermetallic compound layer between weld pool and lower sheet metal which is composed of the
brittle phase of Al3Mg2.
The aim of this research is to evaluate the weldability using LWB process to join Mg/Al alloys using
HLD 3504 – Laser Type Trumpf, to explain the experimental conditions and interpretation of results.
Defects Detection on the Welded Thin Steel Plates Using Vibroacustic Method
BERETEU Liviu, VODĂ Mircea, MEDGYESI Tiberiu, DRĂGĂNESCU Gheorghe, SIMOIU Dorin
The aim of this paper is the development and validation of a vibroacustic technique to welding defects
detection, especially for welded thin plate structures. In welded structures subjected to dynamic cyclic
loads may appear and propagate fatigue cracks due to local structural damage. These cracks may
initiate due to the technological parameters used in welding process, or due to environmental
operating conditions. By the means of Finite Element Method (FEM), the natural frequencies and
shape modes of welded stainless steel specimens are determined. The analysis is carried out in
undamaged condition as well as damaged one, after artificially induced damages. The experimental
measurement of the vibroacustic response is carried out by using a condenser microphone, which is
suitable for high-fidelity acoustic measurements in the frequency range of 40 – 18.000 Hz. The
vibration responses of the welded specimens, in free-free conditions, are carried out using algorithms
based on Fast Fourier Transform. The results are compared to modal parameters estimated using FE
Analysis and with natural frequencies computed by Euler-Bernoulli theory.
Tenacity Evaluation of the Deposited Metals by Welding, Using 3Si-2 Wire of ø1.2 mm on
S355J4 Steel
PASCU Doru Romulus, DUMA Iuliana, DASCAU Horia
The mechanical tenacity characterizes the materials behaviour to static and dynamic shocks, at the
ambient and the negative temperatures. In the case of deposited metals by welding, the tenacity
characterization is made by determining the impact energy, (KV), the crack back contraction, (CBC),
the lateral expansion (EL), and the correlation between these characteristics.
The paper presents the experimental results concerning the tenacity characteristics of the deposited
metals by welding on S355J4 steel (SR EN 10025), using Si-2 wire of ø1.2 mm
(SR EN ISO 14341). These characteristics have been determined by impact bending tests, at the
testing temperatures of + 20ºC, -20ºC, -30ºC, and -40ºC.
The characteristis of the deposited metals tenacity, experimental obtained, had high values at all
the testing temperatures (KV = 96…208 J; CBC = 1.21…2.62 mm and EL = 1.65…3.57 mm), beeing
more than the same characteristics corresponding to S355J4 steel. So, it means that the deposited
metals by welding using Si-2 wire of ø1.2 mm are not susceptible to the embrittlement-cracking
phenomena.
Research on the Influence of Artificial Ageing on the Tensile Properties of Plastic Coated
Composites with Fabric Inserts, in the Presence of Simulated Welding Defects
KUN Lorand, MURARIU Alin Constantin
An experimental research regarding the effects of artificial ageing by UV exposure on the tensile
properties of a plastic coated composite material with fabric inserts, used mainly in the production of
truck covers is presented in this paper. For the purpose of artificial ageing, the authors designed and
built at ISIM Timisoara an original equipment with high performance UV lamps, adjustable geometry
and forced cooling system. Defects of different sized were created in the aged and not aged
specimens in order to simulate potential defects that appear during the joining process of these
materials. The influence of artificial ageing with 24h and 48h exposure and defect size is highlighted
by comparative analysis of the results obtained from the tensile tests that were carried out on all
specimens. The results are further compared to the tensile properties of aged and not aged welded
specimens, obtained using the high frequency current and hot air welding methods. The results show
clear correlation between the defect size and the maximum tensile force and the elongation at break
respectively. It is concluded however that further testing is necessary in the specially built equipment
in order to properly describe the effect of accelerated artificial ageing by UV exposure on the tensile
properties of plastic coated composite materials with fabric inserts.
Reconditioning by Metal Deposition Technology. Temperature Finite Element Modeling
NITOI Dan Florin, DUMITRU Marius Gabriel, DUMITRU Bogdan, MIHAILESCU Alexandru, CISMAS
Suzana Carmen
This article presents finite element modeling for temperature as a result of the metal deposition
technology. In such cases, this is the only research method to offer reliable information, taking into
account the totally unfavorable working conditions for stress and strain gauges. By selecting the most
appropriate initial condition, the output data come very close to the real result. In the paper, the
temperature behavior is modeled because it influences the structural transformation and the stress,
which can cause problems under the circumstances of improper working technologies.
Structural Integrity of Welded Structures Selected, peer reviewed papers from the 10th International Conference on Structural Integrity of Welded Structures (ISCS13), July 11­12, 2013, Timisoara, Romania The conference takes place every two years and is traditionally organized by the National R&D Institute of Welding and Material Testing, ISIM Timisoara in cooperation with the “Politehnica” University of Timisoara and the Timisoara Branch of the Romanian Academy of Technical Sciences. The volume includes 33 papers selected from the 55 papers that were submitted. The authors highlighted the results of their own research and development activity carried out in the frame of their institutes and universities from Romania, Germany, Hungary, Kazakhstan and Serbia.
Distributed by Editor Copyright © 2013 Trans Tech Trans Tech Publications Ltd Publications Ltd, Switzerland General Manager of Kreuzstrasse 10 PO Volume 814 of Advanced National R&D Institute of Welding CH‐8635 Durnten‐Zurich Materials Research and Materials Testing ‐ ISIM Switzerland ISSN print 1022‐6680 Timisoara Fax: +41 (44) 922 10 33 ISSN cd 1022‐6680 Dr. Ing. Alin Constantin Murariu E‐mail: [email protected] ISSN web 1662‐8 Full text available online at http://www.scientific.net/AMR.814 WELDING & MATERIAL TESTING
Publisher:
National R&D Institute for Welding and Material
Testing - ISIM TIMIŞOARA (Romania)
Contents:
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welding processes and advanced material joining
• Synthesis, studies on trends
• Additional information referring to scientific events,
exhibition, editorial news, training activities
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field of welding and material testing
Language: English
Publishing papers: free of charge
Category: B+
Frequency: 4 issues per year
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