Consumable Electrode Research Articles

Additive Manufacturing of Metal Products via Filler Wire Arc Welding (Review)

The paper presents a state-of-the-art review of additive manufacturing and summarizes its development trends. It considers mainstreams of this technology and outlines its methods. The study highlights importance and prospects of the process based on electrode wire arc welding (GMAW and GTAW). It proposes a layered electric arc deposition by a consumable electrode in shielding gases. A peculiarity of this procedure is that a wire is preheated to a temperature of 400-600°С before fed into a zone where metal products are formed. Wire preheating is realized by an additional power supply placed at a distance of 250-400 mm from a wire end to conduct a preheating current. It is suggested this process is suitable for manufacturing metal products in principle. The study has revealed a gradient structure of product walls manufactured using this technology. It is an upper deposited layer only that has a dendrite structure. Layers below it are subject to repeated thermal treatment caused by heat liberation from the upper layer. As a result, a grain tends to the refinement up to 10 μm depth wise. The most important outcome to emerge from the study is that a 4 mm thick frame structure free of defects may be built given that deposition is carried out by a material with a diameter of 1.2 mm in the conditions: current force 120-140А, voltage 22-24 V, deposition rate 300 mm/min.

Research of the technological methods influence on the formation of structure and properties during the additive growth of products from nickel chromium steels of the austenitic class by plasma-jet hard facing methods

The paper considers the influence of a change in the heat rate of a source with time by means of slope control, using the example of plasma-jet hard facing, as well as changes in the original structure due to laminated cool post weld upsetting of the pads, using the example of plasma-jet heat-facing with a consumable electrode (Plasma-MIG). It was found that the formation of the structure is accompanied by metal deposits transcrystallization. It is shown that the use of vibratory actions on the liquid bath by slope control modulating during plasma surfacing contributes to the partial suppression of transcrystallization of the metal deposit: the direction of columnar crystallites growth changes relative to the previous layer, contributes to the refinement of the pine-tree structure, which leads to a change in mechanical characteristics. The best properties are observed when surfacing with slope control with a frequency of 15000 Hz. The use of laminated cool post weld upsetting during the plasma-jet hard-facing by consumable electrode reduces the transcrystallization of the metal deposit. It forms dendritic crystals of an equiaxial form, which leads to the reduction of the morphological grain flow, and the strength characteristics of the fused on alloy exceeds the level of the metal durability fused on without post weld upsetting and materials obtained by traditional technologies. However, the moldability characteristics remain at a high level.

Microstructure Changes related Mechanical Properties of Welded HSLA Steel Plates

Strength and toughness of steel are the most desirable mechanical properties required in several engineering applications such as marine and oil industries. In this work, the influence of submerged arc welding (SAW) process on the evolution of microstructure and mechanical properties of locally produced low carbon steel plates that is used by Marine Industry and Maintenance Company (Misurata) as an alternative to the imported marine steel plates is investigated. Microstructure investigation, tensile tests, impact toughness, and hardness tests for both steels are conducted. Results show that microstructure is affected by the heat input of SAW leading to more uniform structure of ferritic-bainitic and finer grain sizes. Inherently, affecting the mechanical properties since a decrease in toughness in the heat affected zone HAZ and weld metal zone WM compared to the parent metal is observed. It is shown that the imported steel has higher toughness than local steel for pre-welded and welded plates, with imported steel offering significant reduction in toughness when subject to welding. The effect of welding can be related to the microstructural changes of the weld metal and HAZ attained by adapting proper consumable electrode and welding process strategies.

Dilution rate and wear-resistance performance of assisted wire filling cable-type welding wire GMAW of surfacing layer

Surfacing technology is widely used in material surface modification and repair industries, with the advantages of low dilution rate and high wear-resistance performance. The assisted wire filling (AWF) of cable-type welding wire (CWW) gas metal arc welding (GMAW) is an innovative surfacing method, using CWW as the consumable electrode. The dilution rate and wear-resistance performance were studied in this paper. The results show that the weld penetration of the AWF-CWW-GMAW surfacing layer increased with the increase of welding current, which was consistent with the method of CWW GMAW. The dilution rate of the surfacing layer was about 19% lower than that of the CWW-GMAW with the same parameters. Comparing with the CWW-GAMW method, the sample treated by AFW-CWW-GAMW had a smaller dilution rate of surfacing layer, a less wear loss, a smaller friction coefficient and a higher hardness under the same welding parameters. The alloy element distribution of the surfacing layer was higher than that of CWW-GMAW from the weld to the base metal.

Mechanical properties of intermetallic alloys of the Fe – Al system obtained by a combined process from dispersed wastes of mechanical engineering

The article describes the combined process of obtaining intermetallic alloys of the Fe-Al system from dispersed wastes of mechanical engineering. This process is based on a combination of electroslag casting with simultaneous self-propagating high-temperature synthesis. The formation of an intermetallic alloy occurs due to the use as a consumable electrode of a thin-walled steel tube filled with a charge consisting of a mixture of dispersed mechanical engineering waste (chip waste of steel, silumin, forge cinder, fluorspar), ground to a powdery state. Intermetallic compounds of the Fe-Al system have a unique high complex of physical-mechanical and service properties, they can effectively resist the corrosive effects of aggressive media and abrasive wear. These properties of the materials are of practical interest for a wide range of engineering industries. The materials based on iron aluminide Fe3Al should be especially noted. These materials have a low density (~6.7 g/cm3) in comparison with many high-temperature complex alloyed steels and alloys and at the same time their cost is significantly lower. The latter circumstance is due to the fact that in order to ensure a given level of service properties at high temperatures there is no need to use scarce alloying elements. However, there is a rather significant drawback of these materials. It is the brittleness of intermetallic phases, which hinders their widespread use. However, this drawback is leveled by technological methods of synthesizing the materials, leading to a decrease in grain size, elimination of water vapor in charge materials and the gas phase and alloying with chromium. The purpose of this study is to develop the technological foundations for obtaining intermetallic compounds of the Fe-Al system, which differ in the savings of energy and material resources with the recycling of dispersed wastes from mechanical engineering.

Evolution of Inclusions in Incoloy825 during Electroslag Remelting

Fifty kilogram-scale electroslag remelting (ESR) experiments using slag with different TiO2 contents in an electroslag furnace were performed to investigate the size, amount and types of inclusions in an electrode and remelted ingots. The results show that the contents of aluminum and titanium increased and decreased, respectively, compared to those in a consumable electrode. The inclusions in the consumable electrode were TiS, TiN and Al2O3 surrounded by a TiN layer, and the inclusions in the remelted ingots were TiN, MgO-Al2O3 and MgO-Al2O3 surrounded by a TiN layer. With the increase in the height of the ingots, the average size of inclusions increased from 2.5 to 4.4 μm. Increasing the TiO2 content in the slag promoted the formation of MgO-Al2O3 and made the inclusions larger in the remelted ingots. To make the size of inclusions in remelted ingots of Incoloy825 smaller, the TiO2 in the slag should be decreased. The TiS in the electrode was removed during ESR. Part of the TiN dissociated during the reaction between the liquid metal and slag by molten slag, and most of the TiN inclusions originated from the consumable electrode. The Al2O3 inclusions surrounded by a TiN layer in the consumable electrode were finally transformed to MgO-Al2O3 and MgO-Al2O3 surrounded by a TiN layer in the remelted ingots.

Microstructure and Properties of the 308LSi Austenitic Steel Produced by Plasma-MIG Deposition Welding with Layer-by-Layer Peening

This paper investigates the effect of cold working via layer-by-layer peening on the microstructure and properties of a 308LSi steel workpiece produced by the wire deposition welding with a consumable electrode following the principle of 3D printing. The microstructure, phase composition and mechanical properties of the metal are studied before and after the workpiece synthesis. In the microstructure of the workpieces produced by peening, there is, in addition to austenite, a small quantity of fine-dispersed carbides and residual δ-ferrite in the interdendritic spaces. It is demonstrated that the use of layer-by-layer cold working in the process of deposition welding enables eliminating transcrystallization of the deposited metal, promotes an increase in the microstructure’s degree of dispersion and a more uniform distribution of fine-dispersed carbides in the volume of the dendrites. It is found that these structural features of the deposited metal in the additive manufacturing of a workpiece with layer-by-layer peening lead to an enhancement of the strength characteristics as compared to the material produced by the conventional wire deposition welding. Meanwhile, the level of the ductility characteristics remains high.

Kinetic study of control of alloy elements during electroslag remelting of Incoloy825

The present study was motivated to reveal the oxidation mechanism of Al, Ti and Si elements during electroslag remelting (ESR) and propose methods to control them. Three small-scale ESR experiments were carried out with Incoloy 825 alloy as consumable electrode and three groups of slags with different TiO2 contents as raw materials. A kinetic model of slag-steel reaction was established based on ions and molecules coexistence theory (IMCT), film theory and penetration theory. The results show that Al and Si contents increase compared to that of the electrode but Ti content decreases. The increase of Al and the loss of Ti decrease with the increase of TiO2 in slag. The calculated values of the model are in good agreement with the experimental values. In the early stage of ESR process, FeO content increases apparently, so it is more effective to control oxidation in order to obtain uniform ingot. The restricted link of the reaction in the mass transfer of Al + Al2O3, Si + SiO2 and Ti + TiO2 is on the metal side, on the slag side and both sides, respectively. When TiO2 content in slag is lower than 12%, TiO2 addition is more effective. When TiO2 content is higher, adding Al deoxidizer is more effective to control Al and Ti contents.

Mathematical Modelling to Predict Angular Distortion in Butt-welded Aluminium 1200 Plates

MIG welding is an inert gas shielded arc welding process using a consumable electrode. The process finds huge applications in various engineering industries due to its versatility and its ability to get automated. In the present work, angular distortion (AD) occurring in the butt welds has been analysed using mathematical modelling. The important input parameters selected are wire feed rate (WFR), welding speed, and voltage. These variables are taken at three levels to analyse their effect on AD. The investigation was carried out using a statistical design of experiments technique. The ANOVA technique is employed to evaluate the mathematical model's adequacy. The graphical results were evaluated using the response surface methodology (RSM). The optimal combination of input parameters was determined to have minimum possible AD.The present study is expected to provide useful results which may prove beneficial for the aluminium fabrication practices.

Mathematical modeling to predict the weld dilution in FCA welding of stainless steel 301 plates

Flux-cored arc welding (FCAW) is a type of arc welding that employs a constantly supplied consumable tubular electrode that is loaded with a suitable flux. FCAW is gaining popularity as a method of producing high-quality welds for metals such as structural steel, and nickel-based alloys, which are extensively used in industry. Dilution is defined as the change in weld metal composition induced by mixing of the base metal or previously placed weld metal. The current paper analyses the influence of (FCAW) process factors such as welding voltage, wire feed rate, and welding speed on the weld dilution of 301 austenitic stainless steel plates. An attempt is made to build a mathematical relationship between the input parameters and the response parameters, which in this instance is dilution. The statistical technique of design of experiments is used to conduct the studies in a systematic manner. A central composite face-centered approach was used to create the mathematical model. ANOVA was used to evaluate the model's adequacy, and the results were examined using graphical representations.

Numerical Modeling of Ultrasonic Non-Destructive Monitoring for Consumable Electrodes in Metallurgical Electric Furnaces

Numerical Modeling of Ultrasonic Non-Destructive Monitoring for Consumable Electrodes in Metallurgical Electric Furnaces

Research of modification influence on cracking resistance of cast iron in moulds

The research is devoted to determination of influence of grey iron modification technology; this gray iron is used for manufacture of steel casting moulds. Difficult operating conditions stipulate strict requirements both on construction of moulds and on their materials. These moulds materials should reliably withstand to effect of cast steel with the temperature 1600–1700 °C, as well as to thermal shock which is directly proportional to this temperature, to essential cyclic thermal stresses and deformations. Peculiar operating conditions of moulds (such as high heating temperature, mounting on movable and stationary runners, intensive traffic routes etc.) hamper conduction of the required investigations directly during their operation. The research was carried out on physical models of moulds for consumable electrodes of vacuum arc remelting with geometrical similarity scale 1:10. The following mould models for consumable electrodes, cast of iron, were tested: modified by ferrosilicon FS65 (according to the GOST 1415-93), modified by primary aluminium A99 (according to the GOST 11069-2001), modified by vanadium slag ShVD-1 (according to the technical specification TU 14-11-178-86), modified by ferrosilicobarium FSB-30 and by silicomishmetal SIMISh-1. These modifiers were selected owing to their wide use at production facilities. Thereby, the conducted tests were aimed to examine the features of moulds walls deformation and stress-strain state on the models of gray and modified cast iron; they allowed to assess the advantages and disadvantages of obtained structure and graphite inclusions forms. They will also help to develop the most rational form of external surface for moulds designed for section and sheet metal, previously determining destruction features. Application of thinwalled moulds with rational form can provide substantial decrease of their specific consumption. Examination of metal quality which was cast in pilot (lightened) moulds with curved external surface displayed that metal macrostructure for pilot and usual ingots is the same.

Influence of long-term high-temperature action on impact toughness of base metal and weld metal of 22K steel welded joint

One of the applications of construction low-carbon 22K steel (AISI 1022 type) is as a material for the vessel of a core catcher (CC) for nuclear power plants with VVER reactors. In the event of severe beyond design basis accident, the CC-vessel will be under conditions of prolonged hightemperature impacts, which can significantly change the structural state and lead to degradation of mechanical properties of the vessel material. Data on the effect of such actions on the mechanical properties and fracture resistance of welds (the properties of which usually differ from those of the base metal) from low-carbon steels are very limited in the literature. This makes it difficult to guarantee the reliability and safety prediction of CC. The purpose of this work was to carry out the comparative Charpy V-notch impact tests of the samples of base metal and weld metal of the 22K steel welded joint before and after long-term high-temperature heat treatment, simulating the thermal effect on the reactor vessel material of nuclear power plants during severe accidents. Welded joints of 22K steel sheets were obtained by the method of automatic argon-arc welding with a consumable electrode (welding wire SV-08G2S was used) in accordance with PNAE G-7-009–89. Based on the test results, the ductile–brittle transition curves were plotted and analysis of fracture surfaces after tests was carried out. The influence of structural factors on the impact toughness has been studied. It is shown that prolonged high-temperature exposure leads to an increase in the temperatures of beginning and end of the ductile-brittle transition by 30 – 50 °C and to the expansion of range of the ductile-brittle transition temperature by 15 – 25 °C of both base metal and weld metal of the welded joint.

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.

Формування швів при зварюванні стиків з алюмінієвого сплаву АМг5М плав- ким електродом в монтажних умовах без застосування підкладного формуючого елемента та з ним

Формування швів при зварюванні стиків з алюмінієвого сплаву АМг5М плав- ким електродом в монтажних умовах без застосування підкладного формуючого елемента та з ним

Weld formation in consumable electrode welding of butt joints of amg5m aluminium alloy in site with a forming backing element and without it

Weld formation in consumable electrode welding of butt joints of amg5m aluminium alloy in site with a forming backing element and without it

Development of Arc Welding Technology with Support of Stability of Electrode Melting Process

Mechanized arc welding is divided into two main varieties: with self-regulation of the electrode melting process and with automatic process control. The common thing between self-regulating mechanized arc welding and manual arc welding is that in the welding equipment there are no means for automatic control with feedback from the arc. The difference between them is that stabilization of the electrode melting process in mechanized welding is carried out by the source itself, which has a particular volt-ampere characteristic (CVC), by a corresponding spontaneous reaction to a change in the situation in the arc. This method is significantly inferior to the method with automatic process control in precisely maintaining the specified parameters and has a limitation on the minimum current density on the electrode. The method of pulse self-regulation of the electrode melting process proposed in the E.O.Paton EWI removes this problem. However, it requires the use of power sources with a complicated, multi-link CVC curve. Further improvement is revealed through the use of digital controlled, programmable power supplies that have an automatically generated CVC. The combination of automatic source control and self-regulation by the spontaneous reaction to the situation in the arc creates a new hybrid way to stabilize the process of arc welding with a consumable electrode and other related arc processes (surfacing, soldering, re-melting).

Effect of magnetic field on elements segregation in electroslag ingot

In order to improve the production efficiency of electroslag remelting process and the solidification quality of electroslag ingot, a novel electroslag furnace with electromagnetic stirring was designed and the effects of external magnetic field and different electrical parameters on electroslag remelting process were studied. The distribution of carbon, chromium, phosphorus and compactness in electroslag ingot was analyzed through original position analysis apparatus. Results show that the external magnetic field accelerates the remelting of consumable electrode. Under the condition of remelting voltage of 34 V and current of 1500 A, the remelting rate of metal consumable electrode increases from 20 to 27 mm min−1 when the magnetic induction intensity of 62 × 10−4 and 108 × 10−4 T is applied. However, the remelting current decreases from 1500 to 1100 A under the condition of constant remelting rate and remelting voltage, thereby reducing the energy consumption. The effect of external magnetic field on the segregation of different elements in electroslag ingot is different. Under the experimental conditions, the carbon segregation is unremarkable, but the phosphorus segregation is improved when the electromagnetic force generated by the interaction between the external magnetic field and the remelting current is small. However, the excessive electromagnetic force aggravates the segregation of carbon and phosphorus. With the increase in electromagnetic force, the chromium segregation gradually increases.

Consumable electrode – additional filler wire arc interaction control under surfacing (DE-GMAW)

Introduction. Arc surfacing through feeding an additional filler wire heated by an additional arc burning between the filler wire and the electrode wire is considered. Under the conditions of such surfacing, the minimization of the input of the remelted substrate metal into the weld metal is studied. The research objectives are to examine the conditions providing self-regulation of this advanced arc surfacing process, and to evaluate control capabilities of the heat impact power on the metal and on the weld metal flow. Materials and Methods. In solving a wide range of welding and surfacing tasks, it is advisable to use engineering analysis methods based on physicomathematical modeling of processes and phenomena. These include: self-regulation of the arc process under joint melting of the electrode and the filler wires; assessment of the possibilities to control the heat impact power on the metal and on the weld metal flow during the formation of the weld The features of the arc surfacing of anticorrosive chromium-nickel steels on low-alloy steel are considered in the paper. Results. New mathematical dependences are proposed that describe physical phenomena under surfacing with an arc interaction between the electrode and filler wire. A physicomathematical model of the joint melting of the electrode and filler wire is developed. It provides determining the values of the control parameters. In addition, you can find out how much heat affects the substrate from: heat release in the main arc, droplet flows of the weld electrode and filler metal, arc plasma Discussion and Conclusions. It is established how the current and the lengths of the main and additional arcs are affected by the supply voltages. The feed rate of the electrode and filler wire with a diameter of 1.6 mm and 1.2 mm made of Inconel 625 alloy is determined. It is shown what thermal effect the substrate undergoes in this case. It is noted that due to the larger value of the main arc current, the diameter of the electrode wire should be larger than that of the filler wire. The heat flow in the substrate is created mainly by the flow of the weld metal droplets.

ЗАСТОСУВАННЯ ЕЛЕКТРОШЛАКОВОГО НАПЛАВЛЕННЯ ДЛЯ ВИГОТОВЛЕННЯ МОЛОТКІВ УДАРНОГО МЕХАНІЗМУ СТРУШУВАННЯ ОСАДЖУВАЛЬНИХ ЕЛЕКТРОДІВ ЕЛЕКТРОФІЛЬТРІВ

У статті представлено основні дані про технологічні можливості виготовлення деталей для ударного механізму струшування осаджувальних електродів електрофільтрів. Запропоновано й аналітично обґрунтовано перспективність зміни технологічного процесу виготовлення молотка ударного механізму з метою максимального збільшення коефіцієнта корисної дії електрофільтру при одночасному збільшенні експлуатаційної надійності молотків і зниженні вартості їх виробництва. Встановлено, що процес виготовлення молотка практично можна звести до однієї операції – електрошлакового наплавлення. Водночас для вихідних заготовок (хвостовик і витратний електрод) застосовуються стандартні стали стандартного сортаменту. В результаті дослідження якості металу наплавленої ударної частини молотка встановлено, що процес електрошлакового наплавлення забезпечує формування монолітної і бездефектної структури; мікроструктура наплавленого металу – ферито-перлітна, досить однорідна і дисперсна, що характерно для литого металу в водоохолоджуваному кристалізаторі. Ударнівипробування молотків, отриманих з використанням електрошлакового наплавлення, проводили на спеціальному ударному стенді, який забезпечує енерго-кінематичні параметри удару молотка по балці струшування, аналогічні промисловому електрофільтру. Випробування показали їх високу надійність (руйнувань не було) і тим самим підтвердили можливість їх промислового застосування. Розрахований очікуваний економічний ефект від застосування технології електрошлакового наплавлення при виготовленні молотків ударного механізму струшування стосовно розробленої конструкції молотка становив близько 350–400 грн за штуку. Отриманів роботі результати можуть бути використані на виробництві, при проектуванні технологічних процесів виготовлення деталей, що мають складний технологічний процес виготовлення.