Pulsed Arc Welding Research Articles

Hardfacing of GX40CrNiSi25-20 cast stainless steel with an austenitic manganese steel electrode

Abstract To enhance the wear and corrosion resistance of engineering components, various surface modification techniques have been devised. Among these, arc welding processes employing specialized electrodes offer relatively straightforward methods with low production costs for hardfacing applications. This paper focuses on the hardfacing process using pulsed current arc welding to reinforce cast austenitic steel structural components, aiming to prolong their lifespan. Typically, hardfacing coatings utilize Fe, Ni, and Co-based alloys. Among these, Fe-based alloys, such as manganese austenitic alloys employed in our experiments, are favored for their robust mechanical work hardening capacity, resulting in significant hardness enhancements (from 186–219 HV5 in the as-deposited layer to 468–492 HV5 after mechanical work hardening) under intense wear and impact conditions. The innovation of the hardfacing process developed in this study lies in utilizing a universal TIG source adapted for manual welding with a covered electrode in pulsed current mode. This hardfacing technique can be applied to both worn components in operation and new ones before being put into service, thereby ensuring long-term durability and reducing maintenance costs.

Influence of solid-state laser radiation on the process of pulsed-arc welding of aluminium alloy 1561

Influence of solid-state laser radiation on the process of pulsed-arc welding of aluminium alloy 1561

Intermetallic phase evolution and strengthening mechanisms of the titanium and stainless steel lap joints welded by interrupted pulsed arc welding

The study is focused on analyzing the intermetallic phase evolution and strengthening mechanisms of the titanium alloy and stainless steel (Ti-SS) seam-welded joints using interrupted pulsed arc welding (IPAW). The precise adjustment of welding parameters for the IPAW technique allowed for the successful creation of two different joining modes for Ti-SS joints: contact reactive brazing and fusion modes. The homogeneous composition in the brazing joints was achieved by the formation of a diffusion-driven eutectic liquid phase at the joining contact, resulting in an unusual eutectic structure consisting of β-Ti and TiFe. The molten pool at high temperatures caused an uneven distribution of composition and energy throughout the fusion joints. The fusion joints consisted of a Ti-rich layer, containing β-Ti and TiFe phases near the TC4 side, and a Fe-rich layer, containing TiFe2/TiCr2 and α-Fe phases near the 304SS side. The shear-bearing capacity of the joints exhibited an initial increase and subsequent decrease as the heat input increased. The low heat input resulted in the formation of the unwelding zone, which significantly reduced the shear resistance of the joints. With the increase of the heat input, a reduction in shear strength occurred due to the accumulation of TiFe2 brittle phases associated with the shift of the joining mode from the brazing to the fusion. The shear force decreased after reaching its maximum value, despite the joints being fully joined and the joining area expanding.

Numerical Analysis of Thermal Flow Dynamics of Arc Plasma and Molten Pool in Hollow Cathode Arc Welding with Oxygen Content

The mechanism of the pulsed hollow cathode arc welding (HCAW) process was revealed using a fully coupled model with a hollow cathode. We solved the governing equations with the Marangoni effect to study the dynamic behaviors of a molten pool with a square pulsing current (200~400 A, 900 Hz) and varying O2 content; the dynamics of the arc plasma and the weld pool in the HCAW process were investigated quantitatively. The results show that the intensity of the arc plasma was more significantly weakened by the design of the hollow cathode in HCAW than that in GTAW with a solid hollow cathode. We could obtain a stable molten pool even with a large pulsing current section (200 A–400 A) at higher frequencies. The flow dynamics of the molten pool were mainly dominated by the Marangoni effect with varying oxygen content, and we could promote penetration by increasing O2 content in HCAW.

A novel optimizing Pulsed Plasma Gas Variable Polarity Plasma Arc Welding (PPG-VPPAW) method for improving weld quality

To enhance the reliability of aluminum alloy welding quality, a novel Pulsed Plasma Gas Variable Polarity Plasma Arc Welding (PPG-VPPAW) system is proposed. This system enables independent control and rapid adjustment of the plasma gas, allowing for flexible modulation of arc pressure output under constant thermal conditions, thereby reducing porosity and refining grain structure. The research analyzed the impact of parameters of different plasma gas on arc characteristics, welding porosity, and welding microstructure. The results reveal that the periodic changes in pulsed plasma gas induce corresponding variations in arc temperature, arc shape, arc pressure, arc voltage, and the morphology of the weld pool keyhole. The magnitude of the difference between the base value and peak value of pulsed plasma gas determines the extent of arc pressure fluctuations and the behavior of the backside keyhole. The maximum oscillation amplitude of the backside keyhole can reach up to 4.5 mm². Additionally, the oscillation of pulsed plasma gas within the molten pool has been demonstrated to effectively reduce weld porosity and refine grain size. Under this process, the grain size of the weld metal can be reduced by up to approximately 25%. Current work provides an important direction for fabricating highly reliable aluminum alloy weldments.

An innovative pulsed current arc welding technology for armor steel: Processes, microstructure, and mechanical properties

This study presents a novel pulsed current arc welding technology, specifically pulsed current gas tungsten arc welding (PC-GTAW), single and double pulse gas metal arc welding (SP/DP-GMAW), and dual process welding (D-process). This study aims to investigate the effectiveness of these welding techniques for armor steel weldments. This research focused on investigating the welding processes, resulting microstructures, and mechanical properties of welded joints. Based on the macrography analysis, it was determined that the weldments exhibit no signs of porosity, inclusions, or inadequate penetration. This finding substantiates the optimum settings for the weldment production process. The weldment optical microstructure, fusion, and heat-affected zone were examined in the weld interface. The microstructural properties of the FZ include δ-ferrite, austenite, bainite, and acicular martensite. The HAZ has a bainite-untempered martensite microstructure. The chemical composition and variations across the weldment (base, weld and HAZ) were identified. The grain borders contained greater quantities of Cr, Ni, Mn, Si, and Mo than those of the grain cores. EBSD revealed average weld zone grain sizes of 17.7 µm, 32.6 µm, 30.8 µm, and 24.6 µm for PC-GTAW, SP-GMAW, DP-GMAW, and D-Process, respectively.Furthermore, the hardness measurements showed a progressive transition across different regions. Additionally, the D-Process-fabricated material exhibited a maximum ultimate tensile strength of 872 MPa and an elongation of 4%. The mechanical properties exhibited by this new process variant exceed those of other weldments, indicating its potential for fabricating armor steel. The impact toughness demonstrated superior performance in all the weldments. Within this context, the new use of pulsed current advanced welding methods has shown the ability to generate welded parts of exceptional quality.

Structure and properties of welded joints of 13KhGMRB steel in pulsed-arc welding

Structure and properties of welded joints of 13KhGMRB steel in pulsed-arc welding

Numerical and experimental investigation of metal droplet transfer during pulsed bypass-current plasma-GMAW hybrid arc welding

Numerical and experimental investigation of metal droplet transfer during pulsed bypass-current plasma-GMAW hybrid arc welding

Contact reactive brazing of TC4/304 stainless steel dissimilar metals by interrupted arc pulsed welding

The most challenging aspect of producing durable joints between titanium alloy and stainless steel (Ti/SS) is preventing the formation of brittle Ti–Fe intermetallic compounds, particularly the TiFe2 phase. In this paper, the interrupted pulsed arc welding (IPAW) was proposed to join TC4 and 304SS dissimilar metals. The joining mechanisms, microstructures and shear strength of the joints were investigated. The precise regulation of arc pulsed time in the millisecond range enabled the creation of a joint without the formation of the TiFe2 phase through contact reactive brazing. A Ti-rich reaction layer consisting of β-Ti and TiFe phases was formed in the brazing joint, and the shear strength of the joint reached 106.3 MPa. By increasing the arc pulsed current or time, the brazing joint was transformed into the fusion joint. The formation of two reaction layers was observed: Ti-rich phases (TiFe and β-Ti) near the TC4 and Fe-rich phases (TiFe2 and TiCr2) near the 304SS, which exhibited high brittleness. The presence of a high brittleness fusion zone resulted in immediate cracking post-welding.

Microstructures and Electrical Resistivity of Aluminum–Copper Joints

Using pulsed double electrode-gas metal arc welding, aluminum wires are joined to copper plates with fillers of different fractions of silicon. Two layers of different microstructures are formed near the Al-Cu interface: one consists of a hypoeutectic microstructure of α (Al) + Al2Cu, and the other consists of an intermetallic compound (IMC) of Al2Cu. Increasing the heat input causes increases in the thicknesses of the IMC layer and the layer of the hypoeutectic microstructure. Si suppresses the growth of the IMC layer and assists the growth of the layer of the hypoeutectic microstructure. The effects of the interface microstructures and chemical compositions on the electric resistivity of the joints are analyzed. The electric resistivity of the joints increases with the increase in the thicknesses of the IMC layer and the layer of the hypoeutectic microstructure. The law of mixture is used to calculate the electric resistivity of the joints, which is in accordance with the experimental results.

Comparative Study on the Microstructure Evaluation of Al-Mg (Er5356) Aluminum Alloy for Aircraft Wing Stiffener Fabricated By Wire Arc Additive Manufacturing

Wire +Arc additive manufacturing (WAAM) is a type of additive manufacturing process in which layer upon layer is added to form a closely welded component. In this study, Gas Metal Arc Welding - Pulse (GMAW-P) and Gas Metal Arc Welding - Double Pulse (GMAW-DP) methods were used to manufacture the components with 5356 Aluminum alloy. Microstructures of the GMAW-P and GMAW-DP were observed and compared, the results show that the bead formation, Structure, formability and continuity appeared to be better on the GMAW-DP welding when compared to GMAW-P. The pore formations were found in larger numbers in GMAW-P than GMAW-DP. Due to the presence of a larger number of pores in GMAW-P, it is weaker than GMAW-DP.

Achieving polycrystalline transformation and microstructural segregation reduction of nickel-based single crystal super-alloys by ultrasonic pulse arc welding

The sub-grains coarsening and low melting point eutectic are the internal causes of cracking of single crystal super-alloys in welding. Aiming to overcome two internal causes, in this paper, the effect of ultrasonic pulse arc welding on the grains, sub-grains and the precipitations of single crystal super-alloys (IN738) has been comprehensively studied, and the microstructure evolution of IN738 in ultrasonic pulse arc welding has been systematically revealed. The results show that (1) the combined effect of ultrasonic vibration and electromagnetic oscillation not only realizes the synchronous refinement of grains and sub-grains in WMZ (weld metal zone), and the polycrystalline transformation of single crystal super-alloys. A novel 3D schematic model of sub-grains is established to evaluate the size and orientation of sub-grains in 3D direction. (2) The ultrasonic vibration and electromagnetic field induced by ultrasonic pulse current can effectively reduce the microstructural segregation of welds. With the increase of ultrasonic pulse frequency, the size and volume fraction of harmful precipitations (η + δ eutectic, mixed eutectic and MC carbides) decrease greatly, especially the morphology and distribution characteristics of γ′ in HAZ (heat affected zone). Thanks to the above outstanding advantages, ultrasonic pulse arc welding has great application value in single crystal super-alloys.

Microstructure characteristics and mechanical properties of the thin-plate AISI 430 ferritic stainless steel joints by interrupted pulsed arc welding

The feasibility of the interrupted pulsed argon arc welding (IPAW) of the 0.5 mm-thick AISI 430 ferritic stainless steel (FSS) was studied. The results showed that the sound appearances of the butt joints were obtained by the IPAW under different welding parameters. Two joining modes were obtained: (1) typical fusion pool structure with continuous coarsen columnar grain by short interrupted time and low welding speed; (2) snowflake-shape melting pool structure with relatively independent radially grew columnar grain by long interrupted time and high welding speed. The fusion zone (FZ) and heat-affected zone (HAZ) of the joints showed higher microhardness compared to the base metal because of the carbide precipitation and martensite transformation. The joint with a typical fusion pool structure fractured at the fusion zone with a low tensile strength and elongation rate because the weak bonding region between the columnar grains was perpendicular to the tensile direction. The joint with the snowflake-shaped structure displayed a high tensile strength and elongation rate, which was fractured at the BM, as a result of the randomness of the intergranular bonding interface to the tensile direction caused by dendritic radial growth.

Effect of Pulse Current GMAW on the Yield Stress of the S460M TMCP Steel Welded Joints

Thermomechanically cold processed (TMCP) steels with a high level of strength are actively used in various constructions. The high strength of the TMCP steels is acquired due to the formation of the fine-grained structure. Such steels have relatively low carbon percentage. These greatly simplify the solution of the problem of improving the quality and reliability of metal structures. At the same time this raises new questions in terms of the technology for welding such steels. In the first instance, it is conditioned by the complex behavior of the TMCP structure under the welding thermal cycle effect. The most important property of the welded joint is yield stress (YS) which characterizes the workability of the whole joint. The estimation of the YS while developing the welding technology is a valuable task for design. This current research has made a complex investigation of the modern welding technique's effect on the behavior of the yield stress formation in TMCP steel welded joints. For progressive technology development, pulse arc welding was used.Graphical abstract

Influence of pulsed-arc welding modes on the structure and mechanical properties of welds and haz metal of welded joints of 30Kh2N2MDF steel

The Paton Welding Journal, 2022, №05. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Study on arc characteristics of different defects in pulsed micro-plasma arc welding

The shape of welding arc is closely related to the quality of welding. For micro plasma arc welding (MPAW), however, the change of arc shape is not obvious enough to evaluate the quality of welding, due to the small size of welding arc. Thus, it needs to extract the specific features of arc shape through image processing algorithm to judge its change quantitatively. Furthermore, for workpiece with bright surface, it is difficult to extract the arc shape directly from the arc images because of the strong arc reflection on the workpiece surface. In this paper, a new method based on vertical Sobel operator was proposed to overcome the above-mentioned challenges, and to extract the clear arc shapes from the arc images of pulse micro plasma arc welding (P-MPAW). The arc length, arc width and the height difference between two sides of arc were extracted as characteristic parameters to reveal the influence of different welding defects on the arc shape. The changes of arc characteristic parameters have been studied in depth, when there are different defects such as burn through, misalignment, undercut, concave deformation, excessive gap and overlap. The results show that, excessive welding gap and misalignment, caused by the assembly and machining accuracy, have obvious characteristics in the instantaneous arc shape. The defects caused by welding thermal process like burn through, concave deformation, overlap and undercut have their own distinctive characteristics in the changing process of the arc shape.

Effect of parameters of pulsed-arc welding on the formation of weld metal and microstructure of heat-affected zone of 09G2S steel

The Paton Welding Journal, 2022, №03. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Simultaneously improved the strength dramatically and eliminated HAZ softening of DP980 steel pulsed-arc welding joints by PWHT

A pathway of post-weld heat treatment (PWHT) to eliminate heat affected zone (HAZ) softening and improve the strength of the welded joints of DP980 steel was developed. It is found that the high temperature isothermal transition at 750–950 °C followed by water-quenching significantly influences the strength and fracture location by changing the microstructures of the welded joint. The block martensite is distributed discretely in the island ferrite after PWHT, which causes ferrite to deform continuously in space. At the same time, the microstructure of joints is more uniform after PWHT. As a result, the highest strength (1146 MPa) can be obtained by PWHT at 950 °C, which is about 1.35 times that of the as-welded joint.

Optimization of the pulsed arc welding parameters for wire arc additive manufacturing in austenitic steel applications

Industrial development continues to present challenges for manufacturers. One of them is additive manufacturing (AM) with metallic materials. One promising solution is wire arc additive manufacturing (WAAM). Currently, WAAM is a more promising tool for developers, firstly due to the simplicity of its realization and secondly for its cost-effectiveness. Building materials are represented by welding wires, so the deposition rate is favorable. A pulse power source is commonly used in this scheme of realization. Much less attention has been paid to the optimization of the power source working regime, i.e., welding mode. Indeed, the power determines the whole process of WAAM. Therefore, in the present work, an attempt has been made to perform a scientifically based design for the optimal welding mode. The austenitic welding wire was chosen to eliminate phase-transition effects in the solid state of the deposited metal. As a result of the investigation, the advantages of the designed welding mode for WAAM application are made clear. It was shown that the predominant effect on penetration depth possesses pulse current and its input is 49%, while other parameters, i.e., pause current, pulse on time, and frequency, have a less valuable impact. The Taguchi optimization algorithm allowed the development of a specific welding mode for providing better formation of the welds, more grain fined microstructure, and thus improved properties of the modeled wall. Successful efforts have been made to optimize welding modes for WAAM applications. This study is important for manufacturers as well as engineers and scientists.

УПРАВЛІННЯ ПАРАМЕТРАМИ ІМПУЛЬСІВ СТРУМУ ПРИ ЗВАРЮВАННІ ПЛАВКИМ ЕЛЕКТРОДОМ АЛЮМІНІЄВИХ СПЛАВІВ

Pulse-arc welding with a fusible electrode in inert gases occupies one of the leading places among arc methods in the manufacturing of structures from aluminum alloys of responsible purpose. Drops of molten metal of the electrode wire, with the correct selection of pulse parameters, have a small diameter, they do not deform, the evaporation from their surface is minimal and the transfer of alloying elements from the electrode wire to the welding bath is maximal. The problem of the influence of the pulses shape and their parameters on welds and connections during arc welding with a fusible electrode remains unstudied. Therefore, the research on improving the efficiency of pulse-arc welding through the creation of new equipment with enhanced capabilities of management of process parameters is relevant.The development of modern electric welding equipment, including the sources of power for the welding electrode arc, will allow increasing significantly the efficiency of the process. The peculiarity of the use of such equipment is explained by the emergence of many combined and hybrid welding technologies using a pulsed welding electrode arc, for example, laser-arc, plasma-arc. The purpose of the research is to expand the technological regimes of pulse-arc welding with a fusible electrode in inert gases of aluminum alloys by controlling the shape and parameters of the current pulses.Experimental studies on the control of current pulse parameters (duration, frequency, amplitude) and its shape during welding of aluminum alloys AMg6, 1201 and 2219 in argon have been conducted. The obtained dependencies can be used for the development of synergistic equipment for pulse-arc processes.Such equipment will allow expanding the ranges of adjustment of pulse parameters when welding a wide range of aluminum alloys of different alloying systems in different spatial positions and will allow using it in hybrid technologies.