MAIN CHARACTERISTICS OF FUSION AND PRESSURE WELDING …phd.lib.uni-miskolc.hu/JaDoX_Portlets/documents/... · Keywords: weldability of aluminium alloys, fusion welding, pressure welding,

Production Processes and Systems, Volume 5. No. 1. (2012) pp. 91-106.

MAIN CHARACTERISTICS OF FUSION AND PRESSURE

WELDING OF ALUMINIUM ALLOYS

Imre Török1, Krisztina Juhász2, Ákos Meilinger3, András Balogh4 1,4Associate Professor, 2,3Research engineer

University of Miskolc, Department of Mechanical Technology [email protected], [email protected], [email protected],

[email protected]

Abstract

The aluminium and its alloys will be increasingly used for the welded lightweight struc-tures. The essential condition of making high-quality welded joints is to know exactly the weldability and specifications of applied aluminium alloys. Modern, efficient processes should be applied for welding with good reproducibility. This paper provides an overview on the weldability of aluminium and its alloys and describes the modern fusion- and pres-sure welding processes as gas metal arc welding, tungsten inert gas, resistance spot welding and friction stir welding.

Keywords: weldability of aluminium alloys, fusion welding, pressure welding, resistance spot welding, friction stir welding

1. Introduction

Nowadays the utilization of aluminium and its alloys is increasing, more than that of the steels. Basically, this is owing to the application of aluminium alloys in automotive indus-try. More and more expansion of its application appears in the manufacturing of air transport, ship industry, on-shore (cars, trucks) and railway vehicles equally. The effect of high strength steels, titanium alloys and magnesium alloys of these areas mean a serious challenge in terms of its use. Aluminium alloy structures can only be competitive with the steel alloy structures if their weight loss and/or increase in service life can be achieved, additionally modern, reproducible and reliable joining technologies are used at the manu-facturing of high-quality products.

In the field of automotive industry the palette of aluminium and its alloys equally are in evidence hardenable, heat-treatable and cast alloys. These include pre-manufactured prod-ucts as sheets, different profiles, moulded, pressed and forged products [1], [2].

Between the joint technologies of the pre-manufactured products of aluminium and its alloys appear almost all of the shape-, force- and material closing joints. Thus the welding appears on a preferred place at the manufacturing of structural elements [3].

In this condition we analyse the influence of important material properties at welding of aluminium and its alloys, presenting the most advanced, applied process variations of the welding processes, furthermore reveal research topics and results of the department in this field by few examples.

Imre Török, Krisztina Juhász, Ákos Meilinger, András Balogh

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2. Material properties influencing the welding of aluminium alloys

Some physical, chemical, mechanical and technological properties of aluminium and its alloys differ significantly from similar properties of other metals. These differences justify and determine the use of aluminium and its alloys, the application areas as well as signifi-cantly affect the weldability [2], [4].

Analysing the specialities and differences in terms of weldability of aluminium and its alloys should be noted in comparison with steel:

relatively low melting point (480-660°C), there is no discoloration during fusion in contrast to steels, high affinity for oxygen, one of the highest among metals, the high melting point of surface coherent oxide layer (2050°C), high specific heat, twice as much steels, high thermal conductivity, three times greater than the same of steels, good electrical conductivity, four times of steels, high thermal expansion coefficient, twice of steels, varying hydrogen solvent ability, (in liquid-solid phase 20 to 1), different property of heat affected zone, significant changing of mechanical proper-

ties [4], [5]. Relying upon these findings during the analysis of weldability of aluminium and its al-

loys, it is practical to examine and mention the following: crack sensitivity, porosity, pres-ence of oxide layer, and specialty of heat affected zone [2].

2.1. Crack sensitivity

The most dangerous imperfection (failure) of the welded joint is the crack. There are two types of tendency to crack on welding of aluminium and its alloys, cold- and hot cracking.

The incline to hot crack of the joint can be caused by growth of crystals and grains meet but there are liquids between these during the solidifica-tion. Additional period of solidifica-tion the liquid doesn’t get supply. In solidification less and less volume liquid disappears from between of solid grains, arising break of continui-ty which is enlarged and cracked by forming base material [6].

In terms of hot cracking sensitivity of aluminium alloys the temperature interval between the solidus and liqui-dus is significant and determinant. In this field the shrinkage is powerful in the course of cooling, while the joint strength is minimal and has reduced deformation capability.

Figure 1. Dependence of hot cracking sensitivity of the weld on the concentration of

alloying elements

Welding of Aluminium Alloys

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Experience shows if the weld pool contains minimum 15 % eutectic, the hot cracking sensitivity will be reduced to negligible degree. Accordingly the composition of filler mate-rial should be chosen in such a way that it contains minimum 3 % Si or minimum 4,5 % Mg. The effects of these components are shown in Figure 2. [2], [7].

In cast aluminium the necessary amount of eutectic easily available from the point of view of avoids hot cracking inclination. Thus, the higher probability of cracking is, the higher the internal stress has that is the higher overheating, product size, specific shrinkage, the amount of thermal expansion coefficient and stiffer grip.

Taking into account the previous the cracking risk can be reduced by welding condi-tions (joint preparation, rigidity of clamping, width of heat affecting) and welding technol-ogy (welding process, heat input, welding speed) next to the well-selected filler material composition to the welded alloy (alloy and grain refining element) [1], [2].

2.2. Susceptibility to porosity

The gas solvent ability and its degree of metals and metal alloys are dissimilar furthermore these gases take different effect to the properties of metals and metal alloys depending on the value of gas content. Among the trouble causing gases of welding (oxygen, hydrogen, nitrogen) the hydrogen is dominant in aluminium and its alloys. While the hydrogen solvent ability of molten aluminium forcefully depends on the temperature and is significant, till then in solid state this solution appreciably decreases and at room temperature less than 0,001 cm3/100 g metal [5].

Figure 2. The possibility of hydrogen entering to the weld at gas metal arc welding

The appearance of hydrogen caused gas inclusion (porosity) is the consequence and rea-son of this significant difference of melt. Gas inclusions are enhancing the crack sensitivity, resulting embrittlement, significantly decreasing the bending, strongly decreasing the strength (especially yield and fatigue strength) and worsen the corrosion resistance by growing the local internal stress and occurring material discontinuity.

The hydrogen can fall into the weld from different places, so thus from the adhesive moisture of the surface of filler material and base material, from contaminants on surfaces (greases, oils), from absorbed gases caused production of material furthermore from applied


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shielding gases. The welding techniques, welding gun holding and leading influence the hydrogen entering to the weld. Examples for the above described at gas metal arc welding are shown in Figure 2. [8].

At gas metal arc welding the hydrogen entering to the weld is accumulating so thus every place have important function in the formation of total gas content. This is demonstrated by Figure 3.

Total gas content of the weld is possible to reduce primarily cleaning, which should cover the base- and filler material, applied shielding gas furthermore possible to use thoughtful welding technology; it is im-portant especially for high heat concentrated and high speed welding processes.

2.3. Presence of oxide layer

The oxygen affinity is a highlighted influ-encing factor of the welding of aluminium and its alloys which occurs the formation of surface evolving, continuous Al2O3 oxide layer. This oxide layer has formed under natural conditions and in a few hours after removing it is re-forming and embarrassing the welding process. The growth speed of oxide layer thickness is accelerating by rising of temperature. So the more excellent removal of continuous oxide layer is an important condition of fail-safe joint making in the course of welding. This is basically justified by the fact that the aluminium-oxide melts substantially higher temperature than aluminium, about 2050°C and covers the liquid metal continuously, embarrasses the joint making namely the oxide layer, embarrasses the fusion between base and filler material during welding.

There are different methods to remove the oxide layer in certain welding processes dur-ing welding. One efficient solution is to remove the oxide layer at modern gas-shielded arc welding processes by oxide dissolution with cathode vaporization under argon shielding gas. The oxide dissolution with cathode vaporization is a result of a complex process which evolves by the application of direct current reverse polarity while the arc is burning. Then great mass of the positively charged argon ions are colliding with cathode connected oxide layer so forms the cathode spot which migrates on surface and occurs heating in small sur-face. It tears at the oxide layer on this small surface under the oxide layer as a steam explo-sion by reaching the boiling point. The broken oxide layer moves away from the weld sur-face and the neutral argon shielding gas inhibits the regeneration. This effective oxide dis-solution process can successfully applicable at TIG and GMAW processes.

In case of pressure welding the oxide layer removal has ensured by preliminary oxide thinning or oxide forcing with pressure force (by HVox>HValapa. favourable condition), pressing to burr, extruding from the joint line [9].

Figure 3. Estimation of total gas content entering into the weld


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2.4. Specialty of heat affected zone

The most welding processes use heat energy to develop joints. One part of applied heat energy spreads in the work piece and heats it. So the welded material from the weld is af-fected by heat which depends on basically welding process and the thermo-physical proper-ties of the material and it causes changes in different microstructure and mechanical proper-ties. This is especially true for welding of base material which cold formed or quenched aluminium with heat treatment.

In case of cold formed alloys the heat effect is observed due to soft annealing while in case of quenched alloys evolves more complicated, complex zone where we count on re-quenched, softened and segregation zones. In Figure 4., the hardness changes from the weld to the base material (heat affected zone) are shown for different alloys.

Figure 4. Change of the hardness of different aluminium alloys in the heat affected zone

It can be seen from Figure 4. that the mechanical properties of the joint significantly de-clines because of welding heat in quenched materials (Al-Cu-Mg, Al-Mg-Si) which is re-lated to heat-induced structural changes in the microstructure.

2.5. Conditions affecting the weldability of aluminium and its alloys

In terms of weldability of aluminium alloys necessary to consider and ensure the following points to guarantee successful and expected quality:

in terms of prevention of hot cracking desirable: * reducing the temperature gap between liquidus and solidus, * increasing the quantity of eutectic, * application of grain refining elements, * the correct choosing of filler material.

important to avoid cold- and hot cracking * reduction of internal stresses, * avoid the rigid clamping, * correct planning of the joint preparation and design.

prevent and avoid the objectionable gas absorption * ensure the cleaning of base material, filler material and shielding gas, * correct choosing of the technological circumstances.


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in the heat affected zone * cold forming caused strength growth, and/or * losing the good effect of heat treatment in mechanical properties

Taking into account the previous necessary to consider the following points to ensure the optimum properties of welded structures from aluminium and its alloys:

construction design and planning which is beneficial in terms of welded joint, choosing welding process and technology which

* ensures the avoiding of overheating of welded joint, * ensures concentrated heat input and fast heat reduction, * ensures an optimum and co-ordinate the strength between weld and its heat af-

fected zone [2], [6]. The standardized classification of aluminium and its alloy rates the numerous alloys in

nine groups (unalloyed, Cu-, Mn-, Si-, Mg-, Mg and Si-, Zn-, Li-, and other groups) which can be used in different areas. In the automotive industry we can find sheets, different pro-files, cast, pressed and forged semi-products among this material groups [10], [11]. Among these groups are available:

precipitation hardenable, non-heat treatable alloys (e.g. Al99,5, Al99,5 Ti, AlMg3, AlMg5, AlMg4,5Mn),

heat treatable alloys (e.g. AlCu4Mg1, AlMgSi, AlZn5Mg), cast alloys (e.g. öAlSi10Mg, öAlSi12, öAlMg3). It is practical to consider the following points in the choosing of join materials (welding

rods, wires) to welding these materials: the accord of chemical composition and mechanical properties of the weld, the avoid of critical alloys and its amount in terms of hot cracking, alloy burnout, replacement the loss, expectations which act on the function of structural element in the welding of mate-

rial which made from different composition and manufacturing process [1].

3. Joining methods for aluminium and its alloys

The material quality of structural elements and the joint methods used during production influence the application of aluminium and its alloys, the technical standard and cost-effectiveness of semi-finished and finished products. Thus, besides the material selection, the selection of proper joint method should be emphasized as well. The selection and appli-cation field of several joint methods are basically influenced by the property of aluminium and its alloys, the requirements for joints and the size of structural elements. Under appro-priate conditions aluminium and its alloys can be properly joined by joint methods of the engineering practice [12].

In case of the use of reversible joints, reversibility is a basic expectation. Bolted and several mechanical joints are the most spread ones within this joint group. It is important to highlight the fast feasibility, although the increase of weight should be taken into account because of the need of fixing elements.

Numerous irreversible joint variations can be used during the production of structural elements made by aluminium and its alloys. Riveting is one of the oldest irreversible joint solution, which can be rapidly performed in good quality by suitable equipment. Its appli-cation does not require heat input, thus quenched and/or cold-formed alloys can be joined


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without strength loss, furthermore riveting is also suitable for the joint of structural ele-ments from different material.

The application field of brazing and soldering are also limited. Nowadays the new, ad-vanced brazing technological solutions are becoming widely-used ensuring good quality.

In recent years the rapidly developing bonding is also more and more widely used re-garding aluminium and its alloys. By all means its advantage is the simple, rapid implemen-tation, good quality and unlimited application of different materials. In the most cases the weight increase should be taken into consideration because of the additive joint preparation.

Welding is one of the most up-to-date joint methods regarding the production of struc-tural elements made by aluminium and its alloy. Various welding methods have been spread that are suitable for high quality welded joints while ensuring the proper conditions. The most advanced variants of fusion welding processes, used for the production of struc-tural elements, are the gas tungsten arc (GTAW) method and the gas metal arc welding (GMAW), whilst in case of pressure welding resistance spot welding and the friction stir welding are the most advantageous ones [9].

3.1. Advanced fusion welding processes

During the welding of aluminium and its alloys the following advantages of argon can be exploited: without chemical reaction, perfect arc protection, stable arc; perfect oxide disso-ciation, pollutant-free welds; well controlled heat input, process ensuring favourable tech-nological circumstances; possibility of safe welding of thin plates.

Gas tungsten arc welding

Nowadays gas tungsten arc welding (GTAW), as a result of continuous devel-opment, can be considered as one of the most advanced welding methods due to the development of airplane industry and the spread of light metals.

In argon shielding gas the property of arc depends on the material quality togeth-er with the current type and polarity. GTAW is suitable for the welding of sev-eral materials, but it is really the most significant in the field of aluminium and its alloys.

The advanced, electronic controlled, inverter power sources give a new possi-bility for the welding of aluminium alloys by alternating current (see Figure 5.) It can be ensured for instance:

square wave shape alternating current and voltage; change of the ratio between the two half periods, the arc balance; oxide removing; pulsed change and modulation of welding current,

Figure 5. Pulse shape of alternating current [13]


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different pulse shapes (Hiba! A hivatkozási forrás nem található.). the controlled increase of welding current at the weld start for avoiding the cold fu-

sion, and the controlled decrease at the end crater for ensuring the proper filling and avoiding cracking [13].

In Figure 6., an example of the start and end of weld is shown, demonstrating the weld-ing of parts from different materials and manufacturing processes [14].

Figure 6. Weld starting and finishing on base material

Gas Metal Arc Welding

Gas Metal Arc Welding (GMAW) is a modern, heavy-duty arc welding process of welding of aluminium and its alloys. All advantages are typical of this technology which arises of application of argon shielding gas, furthermore evolves on the direct current electrode posi-tive (DCEP) on arcing in argon. In these are deserved highlighting below (without aim to completeness which we have already presented to GTAW):

heat utilization which appearing direct current reverse polarity is advantageous in terms of melting performance, and

on this polarity continually predominate the oxide breaking by cathode vaporization. More modern process variation can be applied over the basic GMAW version as a result

of continuous developing. – arc welding of aluminium and its alloys – in which are de-served highlight:

pulsed GMAW, double pulsed GMAW, alternating current pulsed GMAW [15], etc. The planning, construction and optimization of the heat input process is a complex task.

According to knowledge to date the following material transfer methods available with the usual shielding gases and gas mixtures with two-, three-, four components [16]:

short circuit (short-arc, large drop), large drop transfer (large globular, transition), fine droplet transfer (spray, spray arc)

* traditional, * impulse (planned), * rotating arc.


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Follow from typical properties of each mode of material transfer that suitable to decide on fine droplet transfer with impulse version. The goal is to provide one cycle/one drop principle with a thoughtful harmonization of parameters i. e. drop frequency fcs and pulse frequency fi are equal in normal operation fcs=fi [17].

The medium frequency (100-300 Hz) pulsed GMAW welding drop formation and drop transfer are illustrated in the Figure 7.

Figure 7. GMAW drop formation and drop transfer

The primary advantage of the pulse (non-continuous energy input) version of gas metal arc welding that Ieff (square mean current, root mean square, RMS) can be reduced with changing of pulse parameters (low pulse time, ta; peak current time, tcs; background current, Ia; peak current, Ics). Thus, Ieff<Ikrit is the lower threshold of the fine droplet transfer.

Well-controlled process can be achieved by pulsation welding with the application of current pulses (background current and peak current) on aluminium and its alloys welding, which advantages are summarized below:

the arc stability and uniformity is perfect, fine droplet transfer can be achieved in Ieff<Ikrit range, (Figure 7.) controlled heat input, so the distortion and deformation can be reduced, moderated heat affected zone, residual welding stresses can be reduced, thick wire can be used at welding of thin plates, increasing the diameter of the wire can reduces feed difficulties, controlled material transfer can be achieved, surface/volume ratio is favourable, the melting drop doesn’t run hot, lesser arc temperature, minor loss of the alloying material at welding of Al-Zn and Al-Mg materials, decreasing the risk of porosity, reduce the risk of solidification cracking, continuously prevail the oxide breakdown [18]. All these advantages can be exploited effectively to solve specific task when the con-

ventional GMAW with constant current doesn’t successful. This shows an example of a


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comparative study crack sensitivity and crack propagation, which presents the results of experiments on widely used raw materials for manufacturing of aluminium alloys (AlMg3, AlMg5, AlMg4.5Mn) and welded joints [19]. The welded joints was created by constant current GMAW and pulsed GMAW which ensures controlled material transfer and results homogenous weld composition, lower alloy burn out, favourable weld geometry. Figure 8. illustrates the segment size:

Figure 8. Welded joint made by pulsed GMAW

During the performed crack propagation studies on specimens of the base materials and welded joints it was found that the resistance of pulsed GMAW welded joints are in con-trast to fatigue crack propagation better than conventional GMAW welded joints [19].

3.2. Advanced pressure welding processes

The welding of aluminium and its alloys are not only the fusion processes, but the pressure welding processes may be used in liquid and solid phase version as well. In these days the resistance spot- and seam welding and the friction stir welding come to the front from the latest pressure welding processes especially in automotive industry.

Resistance welding of aluminium and its alloys

The welding and its success of aluminium and its alloys are determined by properties of base material, as low specific resistance, high thermal conductivity, high melting point of the oxide layer and the good formability [2].

At liquid-phase resistance welding the transition- and material resistance ensures the heat (Joule-heat) with high current transition on overlapped work piece. The heat effect and forces applied during the welding together ensure the joint [13]. The high thermal conduc-tivity base material conducts the arising heat on the low specific resistance quickly; there-fore high welding current and short welding time should be used in welding which require short-time welding (or extra short-time welding). An example is presented to demonstrate it in Figure 9


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Figure 9. Weldability lobe of resistance spot welding

This welding can be ensured by well-controlled welding machines of small- and medi-um frequency and stored energy types.

The short-time welding which provided a short-term thermal effect doesn’t result signif-icant softening in the joint environment. Changes of welding current can be provided by modern, well-controlled equipments. Figure 10. shows this.

Figure 10. Changes of parameters during spot welding process

There are three distinct stages in the current curve, a forceful force impulse (1 period) burn the aluminium-oxide, a current reducing to cooling, then the adjusted welding cycle to completion of the welding.

Typical results obtained during the welding experiments in well-controlled equipment are shown in Figure 11. and Figure 12.

Experiments conducted in alternating parameters (Ih, th, Fe) with use 1+1 mm AlMg3 material where the optimization of the joint shear force was performed. It is shown in Fig-ure 11.


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Figure 11. Effect of the welding current (Ih) and electrode force to the (Fe) shear stress

Figure 12. Changes of the heat cycle and the microstructure of spot welded joint (1, 2 weld column, globular crystals, 3 partially melted zone, 4. precipitated zone, 5. re-

crystallized zone, 6. base material)

Figure 12. illustrates the features of joint environment and fast cooling caused short-time welding. The microstructure analyses and the hardness test verified the positive effect of short-time welding [21].

Friction stir welding

Friction Stir Welding is a solid-state process, which means that the base materials to be joined do not melt during the joining process.

In friction stir welding, a cylindrical shouldered tool with a profiled pin is rotated and plunged into the joining area between two pieces of sheet or plate material (Figure 13.).


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Figure 13. The principles of friction stir welding

The parts have to be securely clamped in a manner that prevents the joint faces from be-ing forced apart. Frictional heat between the wear resistant welding tool and the work piec-es causes the latter to soften without reaching the melting point and allows traversing of the tool along the weld line. The plasticized material is transferred to the trailing edge of the tool pin and is forged by the intimate contact of the tool shoulder and the pin profile. On cooling down, it leaves a solid phase bond between the two pieces [22].

Friction stir welding can be used to join aluminium sheets and plates without filler wire or shielding gas. Material thickness from 3 to 50 mm can be welded from one side at full penetration and without porosity or internal voids. Materials that have been successfully friction stir welded to date include all aluminium alloys, copper, magnesium, lead, zinc, unalloyed and stainless steel.

There are 3 important variables in this process: rotation speed, welding speed, tilting angle. There is an opportunity to control the down force in modern equipments, that results

equable quality. The Welding Group of Department of Mechanical Engineering experiments with the

friction stir welding of aluminium and its alloys. The object of current research is that the above-mentioned parameters are aligned to ensure a good quality of joints. The slight devi-ation of the parameters influences the success of this process. For this reason we have per-formed experiments with different rotation- and welding speed. We examined the complet-ed welds with macroscopic examination to detect lack of fusion and grain size growth.

The lack of fusion is clearly visible on the Figure 14. a.). Some parts of the weld were not welded so the joint quality is insufficient.

The high angular velocity and the low welding speed results too much heat input so we can see grown grain size around the root. Naturally it significantly degrades the mechanical


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properties. Figure 14. b.) shows a macroscopic picture from cross section of a weld, where a higher rotation speed and lower welding speed was applied by us.

Figure 14. Friction stir welded joint a.) lack of fusion (n = 500 rev/min, vh = 125 mm/min),

b.) grain size growth (n = 800 rev/min, vh = 63 mm/min)

The correct setting of the parameters results good quality as Figure 15. shows.

Figure 15. High quality weld n = 1000 rev/min, vh = 250 mm/min

There is no grain size coarsening or lack of fusion in the picture. It is planned to contin-ue the experiments with different wall thicknesses, materials and tools.

4. Summary

On reviewing the features of weldability of aluminium and its alloys, analysing of applica-bility circumstances of modern welding processes on manufacturing of aluminium struc-tures, and taking into account our experience in this area, the following conclusions can be drawn.

1. The physical, chemical, mechanical and technological properties of aluminium and its alloys require a circumspect, comprehensive and mindful planning of welding technology. Advanced and well-controlled process should be chosen to make a reli-able and reproducible joint.


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2. In recent years, developments in electronics and electrical engineering allowed the replacement a part of continuous energy input welding by periodic energy input welding. The application of periodic energy input at fusion welding processes has number of determining advantages in welding of aluminium and its alloys:

beside the application of alternating current, the appearance of modern processes of gas tungsten arc welding ensured a * pulse change and modulation of welding, * change of two half-period rate, possibility of arc balance, * control of current up- and down-slope to avoid cold fusion and end crater crack;

the primary purpose of periodic energy input of gas (argon) metal arc welding (GMAW) to influence the drop transfer, the possibility of drop frequency planning, which ensures * predictable and controllable linear energy, * avoid the loss of alloying element, * favourable joint properties.

3. Not only fusion welding but pressure welding can successfully be applied to weld aluminium and its alloys. In automotive application the resistance spot welding and friction stir welding are getting more and more attention, because:

the short-time welding and change of welding current during time can be successful to break the oxide layer on modern and well-controlled equipment,

the friction stir welding which ensures high quality joint without gap and filler mate-rial on structural elements.

5. Acknowledgement

This research was carried out as part of the TAMOP-4.2.1.B-10/2/KONV-2010-0001 pro-ject with support by the European Union, co-financed by the European Social Fund. Authors would like to say special thanks for the financial sponsorship.

6. References

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[5] Kálmán, I.: Az alumíniumhegesztési sajátosságai, Hegesztés technika, XVI, (2005), 3. szám, p.: 13-17.

[6] Köves, Z.: Alumínium kézikönyv, Műszaki Könyvkiadó, 1984, Budapest [7] Burai, Z.: Az alumínium és ötvözeteinek hegesztése, Oktatási segédlet, NME, 1983,

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[9] Török, I.: Hegesztő eljárások II. Sajtolóhegesztés, IWE oktatási segédlet. ME, MTT, 2001. p.: 1-125.

[10] Baránszky - Job, I.: Hegesztési kézikönyv, Műszaki Kiadó, 1985, Budapest [11] Szunyogh L.: Hegesztés és rokontechnológiák. Kézikönyv. 2007. GTE. P.1-888. [12] Török, I.: Kötéstulajdonságokat befolyásoló tényezők alumíniumötvözetek folyó-

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MAIN CHARACTERISTICS OF FUSION AND PRESSURE WELDING …phd.lib.uni-miskolc.hu/JaDoX_Portlets/documents/... · Keywords: weldability of aluminium alloys, fusion welding, pressure welding,