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The results of experimental studies of some features of non-consumable electrode welding in argon steel 12X18H10T with increased speed are presented. The possibility of improving the quality of for...

The authors focused on a buried-arc phenomenon for a high-efficiency thick-plate welding and developed a ‘low-frequency modulated voltage control’ in order to stabilize a buried arc in a high-curre...

The electromagnetic nature of the arc pressure, which is the result of the pinch effect, i.e. compression under the action of its own magnetic field, is confirmed. The pinch effect and compression ...

It has been well known that, in GMA welding, various welding phenomena are largely affected by the type of shielding gas used. However, up to the present time, almost no attempt has been made to ut...

The paper clarifies the influence of TIG and EB welding variants and highly temperature-resistant cast nickel super alloy-shaped parts being in a heat-hard enable condition on mechanical properties...

The paper clarifies the influence of TIG and EB welding variants and highly temperature-resistant nickel superalloy VG159 being in a heat-hardenable condition without post-heat treatment on mechani...

Arc welding is important technology for manufacturing that is directly linked to quality and productivity. Especially GMAW with Ar or CO2 shielding gas is widely used in various industries because ...

Special features of the process of shunting plasma arc current with a consumable electrode are investigated. The effect of the diameter of the consumable electrode, its visible extension and plasma...

Spectroscopic measurements for gas-metal arc (GMA) phenomena have been recently performed. The studies have reported that the metal vapour behaviour greatly affects the arc properties. However, the...

The results of investigation of the special features of changes in the structure of welded joints in 1201 aluminium alloy at different speeds of welding with a constricted arc are presented. It is shown that the reduction of the holding time of liquid metal in the appropriate temperature ranges determines the solidification rate of metal and the extent of diffusion processes of alloying elements and impurities and also the nature of structural changes.

This paper evaluates indications of arc constriction by the thermal and electrical insulation caused by oxides of a single component in A-TIG welding of austenitic stainless steels. Changes in arc ...

Methods for deposition of wear-resisting coatings are examined. Criteria for selecting the surfacing technology and welding material are outlined. The results obtained for the hydroabrasive wear of composite coatings produced by arc surfacing by the basic technology and ex situ and in situ methods are presented

The electromagnetic nature of movement of liquid metal in a weld pool is discussed. When increasing the welding speed as a result of decreasing the induction of the magnetic field at the back of the arc and increasing the electromagnetic force directed forward and reducing the size of the active arc spot, the speed of movement of the liquid metal increases in welding in the direction from the current supply and rapidly in welding towards the current supply. This confirms the electromagnetic nature of formation of undercutting. A method is described for high-speed one-sided welding with a compound electrode in which the active spot of the arc becomes larger, the arc and liquid metal of the pool move forward, the electromagnetic forces directed downwards in the area of the side edges of the pool decrease, and the resultant welded joint is of high quality without undercutting, the reverse bead forms on a flux cushion and the impact toughness of welded joints increases.

The data obtained for the variation of the melting rate and voltage in CO2 welding with the change of the electrode extension are analysed. The dependences of the mean resistance of the unit length of the extension, the increase of the melting factor and the arc voltage on the electrode wire diameter are determined. The appropriate approximating dependences are derived. The average value of the melting factor in the reverse polarity arc at zero extension is determined.

Results of investigations and development of the highly productive technology of submerged-arc large components with a composite strip electrode are presented. It is shown that selecting the optimum dimensions of the composite strip electrode and the welding conditions ensures high quality of formation of the bead in depositing the sub-layer and the wear-resisting layer.

The results of investigation of the conditions of formation of macroheterogeneous compositions, deposited with a compound strip electrode, are presented. Mathematical modelling and experiments were carried out to examine the effect of the gap between the main and side strips on the formation of the weld pool, the conditions of formation of the dissimilar composition in the structure and the distribution of hardness within the limits of the single bead. High impact toughness was found in the deposited multilayer compositions with the alternation of the areas of high strength and high ductility within the limits of each layer and with the displacement from layer to layer.

The characteristic features, criteria and algorithm of the currently available method of self-regulation of the arc in mechanised arc welding with a constant consumable electrode feed rate are investigated. The main problem is that when it is necessary to reduce the welding current, for example with an increase of the thickness of the welded edges or the leg length of the fillet welded joint, welding should be carried out with a wire with a smaller diameter, down to 0.5 mm or even 0.3 mm. This complicates welding technology and increases the price of the wire because of multiple drawing of the wire to the small diameter. Therefore, the main task is to improve the algorithm of self-regulation of the arc and, consequently, reduce the minimum value of the current density, lower than 30 A/mm2 for a steel wire with a diameter of 5 mm at which self-regulation of the arc is still possible, in order to widen the technological possibilities of the method and reduce the cost of technology. The authors believe that ...

The problems of the effect of surface roughness of fluxed-cored wires on technological characteristics are investigated. The surface condition of the self-shielding fluxed-cored wires for surfacing hot pressing tools is analysed. The experimental results show that the reduction of the surface roughness of the fluxed-cored wire with the sheath produced from 65G steel reduces the intensity of pulsations of arc voltage, surfacing current, widens the working conditions range and increases the service life of current conducting terminals.

Measurements of arc plasma are important for determining the associated physical properties. Such measurements usually involve the use of spectroscopic techniques to measure temperature distribution in free-burning arcs. Most studies have reported the temperature of axially symmetric arc plasma using Abel inversion. This method cannot be used for axially asymmetric arc plasma such as two-electrode TIG arc plasma. It is a complex phenomenon because the arc plasma generated from each electrode is affected by the other due to electromagnetic force. We measured the temperature distribution of tandem TIG arc plasma three dimensionally with a one camera rotation system. The measurement method includes the multi-directional detections and the image reconstruction technique: maximum likelihood–expectation maximization. We evaluated the influence of the number of detection directions on the reconstruction by virtual intensity distribution and found that the sufficient direction number is 6. As a result, we could m...

An equivalent volume heat source with the arc power, uniformly distributed in the half-ellipsoid, the axes of which are equal to the half-width of the welded joint and the penetration depth, is proposed. The experimental and calculated thermal cycles in submerged arc welding are in good agreement. The effect of the calculation error on the evaluation of the cooling time in the volume of the softening zone is analysed.

Arc welding phenomena have been theoretically investigated by using various numerical models, which have been proposed and developed together with rapid progress of the computer technologies. However, most of the numerical models are two-dimensional axial symmetric models that are available only for stationary arc on the flat plate. Actual welding processes applied to the manufacturing field are carried out with various joint geometries and the welding arc moves on the base metal. Therefore, they should be non-axial symmetric phenomena and it is required to be discussed with a three-dimensional (3D) model. In this research, TIG arc characteristics in V-groove welding are numerically investigated by using our 3D numerical model. It is shown that both heat input and arc pressure on the groove surface are significantly different from the flat plate surface. In the groove heat input and arc pressure are varied sensitively with location and aiming of the TIG torch. Experimental results show the validity of cal...

The main relationships governing the movement of the cathode (anode) spot of an electric arc, in particular, the effect of rotation of the arc spots, which can be visually investigated at low arc currents, are investigated. The reasons for this phenomenon are explained on the basis of the vortex electrodynamic model of the electric arc in which the current-conducting channel in the plasma arc column has the structure of the dynamic cylindrical coaxial condenser. This phenomenon must be taken in the analysis of the processes taking place in the weld pool because the rotation of the channel of the plasma arc column is the reason for the effective rotational displacement of the material of the weld pool.

The article describes the results of development of a physical–mathematical model of a power source–arc system in plasma cutting which takes into account the instability of arcing at low currents (pilot arc), the process of transition of the arc to the working load and the non-stationary characteristics – the shunting mechanism of the DC arc, causing changes in the length of the arc and large-scale pulsations of current and voltage.

The methods for synthesis of arc surfacing using holding, displacing, vibroarc and cutting effects are developed. The concept of waste-free machining by cutting and a number of technological measures (flexible alloying and nano-reinforcement, multi-electrode processes, directional cooling), expanding the technological possibilities of surfacing, is described.

Each arc welding method has its own characteristics resulting from the range of process parameters used, properties of the welding arc (chemical composition of the arc environment, type of electrode, etc.) as well as the mode of metal transfer, thus creating specific requirements regarding both static and dynamic welding power sources. This article presents selected aspects concerning the determination of output characteristics of welding power sources based on previous studies as well as the prospect for further research.

The results of scientific investigations are summarized and the examples of practical application of the focused light beam of arc xenon lamps for soldering various components are described.

Despite very rapid development of science in the recent years, the phenomena occurring in the electric arc have not been fully recognized. The main reason for this situation is their the complexity as well as very high temperatures. This paper presents the results of numerical calculations of phenomena which occur in the welding arc. The CFD Fluent package was used for modelling the following phenomena in the electric arc: melting, solidifying, generation of heat and multiphase flows. The 3D Model of a 50 × 30 × 6 mm metal plate segment padded with the use of the MIG method with a wire of 1.2 mm in diameter was developed. The paper focuses on presenting the distribution of temperatures in time, the process of melting and later solidifying of the material, as well as on the transport of the material from the arc to the padding weld. It also shows the initial verification of the model by comparing the results with a picture recorded by thermovisual camera.

This article reports the results of a study aimed at using statistical methods to optimize the parameters for laser–arc hybrid butt welding of Ti6Al4V titanium alloy sheets with a thickness of 3.0 mm. The study has examined the effects of the hybrid welding process parameters, such as laser beam power, arc pulse frequency, arc length, arc current, wire speed, laser and arc relative positions, and weld speed. Microstructure has been studied using light microscopy and morphological analysis of weld bead cross sections. This article reports the results of energy and morphological tests.

Output power control methods of the resonance direct-voltage transducers for welding and related processes and technologies are given. Comparative analysis of the frequency and latitudinal control methods is carried out. Their advantages and disadvantages are explained.

Calculation expressions for the welding current magnetic field intensity distribution in the welded product and current density in the welding arc are obtained.

Coating deposition modes and techniques on the surface by manual arc under conditions of process pulsed variation of power data on the surface of parent metal and welded joints from the austenitic steels are developed.

The use of pulsed current for MIG welding of aluminium, despite being one of the most recommended technologies, due to its better results, presents difficulties at the start of the process, principally in regard to arc initiation. With the aim of developing a more suitable process of arc initiation, two new techniques were studied: the first based on the imposition of a high current, combined with an interruption to wire advance, and the second using the application of a low current, linked to wire return, which necessitated perfecting a wire feeder. The first technique, despite ensuring arc ignition, resulted in two forms of initiation condition by the geometry of the wire point. One of them is explosive with ignition close to the middle length of the electrode wire, and the other smooth with ignition close to the point of contact between the electrode wire and the base metal. The second technique, regardless of the geometry of the wire point, promoted smooth initiation, with low heat support and arc ign...

The objective of this work is to evaluate the behaviour of short-circuit frequency and duration time and electrical conductivity during arc re-ignition in the shielded metal arc welding process with alternating current and E6013 electrodes. The non-parametric statistical analysis guarantees robust processing of the data, reducing the influence of atypical values and errors derived from the use of approximations to well-known continuous distributions. The median and the median absolute deviation (MAD) with respect to the median of the data are the localization and dispersion estimators used, respectively. The electrode set at 160 A shows a better stability in metal transference, given for the lowest value of MAD for the short-circuit period (39.36 ms), and the MAD of the short-circuit duration (1.43 ms), according to the presence of a major electrical conductivity during the arc re-ignition (1766.17 × 10− 3 S s− 1).

Data on the direction and speed of liquid metal flows in the pool in consumable electrode arc welding (surfacing) are scarce and contradicting and relate mainly to the process without the effect of...

To ignite an electric arc, it is necessary to supply energy for electron emission. Depending on the method of energy supply, the methods of emission of the arc can be divided into the following pro...

The control of electrode metal transfer in arc mechanized welding and surfacing is one of the main problems in welding because transfer determines not only the quality of the welded joint but also ...

Experience with the development and application of plasma cutting of metals using reversed polarity current and mixed gas supply is described. The high efficiency of plasma cutting with reversed polarity in both the manual and automatic cutting modes in the plant conditions is stressed. It is noted that the number of activations of the constricted arc can be greater than 1000 without failure of the electrode.

Special features of the application of power sources for mechanized welding are described. The advantages of the MAGMA-315 inverter power source in comparison with traditional rectifiers are investigated.

Submerged-arc surfacing or surfacing with self-shielding flux cored wires is accompanied by the formation of a slag layer on the surface of the welded joint. The slag layer consists mainly of oxide...

This work covers short-circuit metal transfer in the MIG/MAG process, where the current is the direct regulation variable, in contrast with the conventional mode in which the direct regulation variable is the voltage. It sets out the general theory for this technique and describes a new system, not yet commercially offered, developed by LABSOLDA at UFSC. The control bases of the process are described, presenting oscillograph results and performance results in relation to root passes and production of splatter. In addition, some results from an existing commercial system are set out with the aim of making direct comparisons between the control strategies and the implications for the largest dependent factors, such as drop diameters, average current, arc efficiency and arc power. Questions are posed such as the criteria for monitoring the variables and the calculations for arc power, which are as important for these new technologies as they are in the case of conventional systems.

The search for competitiveness in the modern industries, represented by demands for higher productivity and cost reduction, leads to investment in new technologies. This is the context in which the double-wire MIG/MAG process was conceived; the idea was to design a process that combines the versatile features of the MIG/MAG process with the high productivity of the submerged arc process. The objective of this work was to evaluate the influence of different arc lengths, at the same current level, on the metal transfer modes and the bead geometry profiles. Using equipment consisting of two linked power sources and a torch with single electrical potential, the series of welds was carried out at three different arc length conditions. A methodology to obtain different arc lengths at the same current and wire-feed speed levels was proposed and validated. The metal transfer was observed using the shadowgraph technique with a high-speed camera, while the geometry was evaluated from macrographies of weld bead tran...

(2007). Laser-MIG arc hybrid welding of aluminium alloy - Comparison of melting characteristics between YAG laser and diode laser. Welding International: Vol. 21, No. 1, pp. 32-38.

The space GHTA (Gas Hollow Tungsten Arc) welding with a high-voltage high-frequency device for arc initiation may cause electro-magnetic noise problems for the computer equipment placed on the ISS (International Space Station). It was also clear from the experiments using a high-voltage DC device for arc start at the ISS orbital pressure, that there is a shifting phenomenon in which a spark discharge shifts to either a glow discharge or an arc discharge when starting the arc. Welding projects around the ISS in space need an arc discharge and a device which does not produce electro-magnetic noise for arc start. Therefore, in this report, arc starting experiments of the space GHTA welding using a touch start technique for arc start were carried at the ISS orbital pressure, 10-5 Pa. As a result, the space GHTA welding using a touch start technique can be used for arc initiation when welding at the ISS orbital pressure. It was also clarified that the application of the touch start technique is optimum in order to use the space GHTA welding process in space.