Influence of longitudinal control magnetic field on efficiency of the arc process

Problematic. When surfacing and welding with the action of a longitudinal magnetic field (LMF), the productivity of melting of the electrode metal increases, it is possible to control the geometric dimensions of the cross-section of the surfaced beads and welds, the structure of the surfaced metal and welds is refined, the hardness increases, the strength and ductility of the weld metal increases, and the resistance of the welds hot cracking. Research objective. Analyze the literature data on the effect of LMF on the efficiency of the arc surfacing process of worn-out surfaces of parts and structures, taking into account the magnetic properties of electrode wires and base metal to increase the efficiency of this process. Realization technique. Experiments were performed on submerged-arc surfacing with Sv-08A wire with a diameter of 5 mm with the action of an alternating LMF. Investigated the effect of the LMF frequency on the depth of penetration of the base metal and the width of the surfaced beads. The results of research. It has been established that at frequencies of the LMF within the range f = 5...50 Hz, the penetration depth is less, and the width of the bead is greater than in surfacing without the action of the LMF. In the future, it is necessary to carry out studies on the effect of LMF during surfacing with flux-cored wires and strips on the metal structure of the surfaced beads and their service characteristics. Conclusions. It has been established that for grinding the structural components of the metal surfaced with the action of LMF, it is necessary to ensure effective mixing of the liquid metal in the weld pool, that is, along its entire length. In this case, it is necessary to ensure the optimal parameters of the control magnetic fields. There is no theory that would explain the mechanism of refinement of the weld structure during arc surfacing with the action of LMF, and the existing views on this mechanism are contradictory. The data presented in the literature refer to the process of arc surfacing and welding with solid wire, there are no data on surfacing using flux-cored wires and strip electrodes.

Modeling the behavior of direct current electromagnetic forces acting on a drop of liquid metal during electroslag remelting

The article presents mathematical and computer modeling of the behavior of liquid electrode metal drops during the process of electroslag remelting (ESP) at a constant current source. The study of the effect of electric field created by direct current allowed us to show the deviation of the drop trajectory from the electrode axis. The flow of electrons and drops of the electrode metal are exposed to electromagnetic forces, which leads to their displacement relative to the remelted electrode axis. This effect entails destabilization of the liquid metal bath and crystal heterogeneity. In turn, the use of external influence on the flow of ESR process can make it possible to stabilize the liquid metal bath even with the use of direct current. Centrifugal forces can act as such forces. They can arise when implementing the technology with the consumable electrode rotation around its own axis. To establish the optimal parameters of rotation speed, it is necessary to estimate the magnitude of impact of the magnetic field that occurs during direct current remelting process. The modeling was carried out using the Ansys Fluent 16.0 software package on the example of remelting 12Kh18N10T steel under the flux ANF-6. The algorithm for calculating of Ansys Fluent is based on the finite element method. In this paper, the mathematical apparatus was not changed and was used in its initial form. The method of magnetic induction was used. The database of information about the ongoing process was built on a grid of finite elements with certain, but sufficient level of adequacy and quality. Each element contains information about the model at a given point, specified for this modeling process. We have revealed the change in the trajectory of the electrode metal drop by electric field from the opposite direction along which the drop flows. The average length of the path traversed by liquid metal drop from the mold axis to the inner surface is from 5 to 15 cm. The motion of an electrode metal drop without an external magnetic field was simulated. This simulation made it possible to determine (estimate) the direction of movement of electrode metal drops and the indicator of necessary external force to stabilize the liquid metal bath during ESP process at direct current equal to 0.067 N.

Arc Technological Characteristics and Metal Transfer Behavior of Twin Electrode GMAW Deposition

Experiments proved that the arc voltage influences its spatial form and electrode metal transfer behavior characteristics during twin electrode GMAW with a single power source. Two specific arc forms were revealed for two corresponding types of metal transfer. The V-shaped arc exists on the melt drop common to the two consumable wires at voltage rate 24-27 V. The columnar shaped arc is formed due to voltage increase up to 34-36 V, which results in increased mobility of the cathode spot in the weld pool surface. As a result, the arc travels between the ends of two electrode wires, and the metal is transferred in drops of small size. It was demonstrated that for the common drop formation the gas mixture of 82% Ar+18% CO2 is preferable to pure argon. It decreases the surface tension on the boundary between the melted electrode metal and the vapor-gas mixture, resulting in the increased volume of the common drop. It was found that a consistent common arc from two electrode wires decreases dilution is made up 43%, which is 1,65 times more and improves the deposited metal formation quality.

State and development directions of systems and methods for electrode metal transfer, joint and surfacing layer formation control during electric arc mechanized and automatic welding—surfacing

The problems that are associated with solving the problems of energy saving, improving in the quality of welded seams and deposited layers in mechanized arc welding and surfacing processes are considered. Shown is wide range of technical and technological methods, influences, techniques that allow to greater or lesser extent to solve these problems with the use of basic and additional hardware, and with the use of new electrode materials, protective media and activating materials. Particular attention is paid to equipment using pulse algorithms of functioning, as well as combined systems of influence on the arc process, which will allow covering wider range of effect on the formation of welded seams and deposited layers. Some of the technical and technological solutions require further researches in terms of specific tasks of welding and surfacing production, as well as the choice of affordable and perfect element base and material resources.

Determination of Parameters of Electrode Metal Transported Drops by Simulation and Visualization

The nature of the molten electrode metal melting and transfer is the main process parameter of manual metal arc welding (MMA) with coated electrodes. It significantly affects the efficiency of the welding process. For this reason the relevant task is to identify the parameters of the transferred molten electrode metal drops and their further transfer into the weld pool with maximum accuracy. The aim of the given paper is to develop a method and visual representation of the form and the geometrics (volume, area, mass) of a molten electrode metal drop.We have developed the method of simulation modeling and visualization for molten electrode metal drops transfer and their parameters. It allows obtaining highly reliable input data to be used for developing and verification of mathematical models for the thermal fields distribution along the welded item surface. The algorithm is realized as the calculation programs for specifying the molten metal drop parameters and means of its geometrics and space form visualization.We used this method to specify a number of molten electrode metal drop parameters: volume, mass, center-of-gravity position, surface area.We have established that it is possible to conduct the measurements with maximumThe suggested method significantly decreases the labor intensity of experimental studies aimed at specifying the size of electrode metal drops in comparison to the standard methods. When we know the size of the drops under certain welding conditions we can control the drop transfer process, i. e. reduce the heat input into the welded item and produce weld joints with the tailored performance characteristics.