Characteristics Of Arc Plasma Research Articles

Numerical study on the effects of discharge parameters on vacuum arc plasma

Studying the characteristics of vacuum arc plasma within a wide range of discharge parameters is vital for its applications. In this study, specific parameters of vacuum discharge, such as cathode temperature ranging from 6000 to 8000K , emitted electron temperature spanning from 0.69 to 2.5eV , and arc burning voltage within the range of 16−30V , have been selected to analyze the effects of these parameters on the cathode erosion, cathode potential drop (CPD), and ion velocity. A validated one-dimensional spherical PIC–DSMC cathode spot model is employed to simulate the generation and expansion of vacuum arc plasma. The results indicate that increasing the cathode temperature and the emitted electron temperature enhance the cathode eroded mass. However, this mass diminishes as the arc voltage increases due to more Cu ions and Cu atoms returning to the cathode under high CPD and charge exchange collisions, respectively. The cathode current density remains nearly constant within the explored range of cathode temperature, but increases with shifting the emitted electron temperature and arc voltage. A higher cathode current density, coupled with the positive cathode plasma resistance, induces a higher CPD that significantly surpasses the cathode sheath voltage. Furthermore, a higher ion velocity is observed at increased arc voltage due to the higher cathode current density, which generates stronger electron friction for accelerating ions. These findings could be valuable in designing a suitable arc voltage for vacuum electric thrusters to enhance thrust.

Plasma characteristics of medium voltage AC air arc discharge and its application on arc electrical parameters calculation

Medium voltage (MV) AC air arcs occur frequently in distribution networks. An electric arc can easily cause electrical fires, leading to serious accident consequences. Obtaining the electrical characteristics of arc faults through arc models is a crucial measure to detect and prevent arc faults. The arc electrical characteristics are affected by many factors such as the ambient air pressure, current magnitude, and arc length, and it is difficult to describe it in an analytical form. The widely used conventional black-box arc model reflects the influence of multiple factors on the electrical characteristics of arcs through fitting or empirical formulae. The model ignores the intrinsic physical and chemical processes, and the applicable range of the model is limited. Focusing on this problem, based on the physicochemical processes of the arc in the arcing and post-arcing stages, a relationship between the electrical and plasma characteristics of the MV AC air arc was established. Subsequently, the arc plasma characteristics were determined experimentally, and were applied to the calculation of the arc electric characteristics. Finally, the calculation results of the arc electrical characteristics were verified using the experimental results, providing a basis for related model improvements and applications.

Strengthening of Al/Cu dissimilar joint due to complicated interface produced by pulsed TIG welding with a constricted nozzle

Al/Cu dissimilar welding is a key technology for weight reduction in fabricating high-functional products, however, conventional tungsten inert gas (TIG) welding is difficult to be applied due to a large fusion area. The constricted nozzle equipped inside the conventional TIG torch has been developed and can improve the position accuracy of tungsten electrode and arc plasma characteristics, moreover increase the heat input density. In this study, 0.5 mm-thick Al and Cu dissimilar sheets were butt welded using pulsed TIG welding with the constricted nozzle under two welding speed-current combinations of 50 mm/s-85 A and 100 mm/s-105 A. The 50 mm/s-85 A joint exhibited that Al and Cu mixed each other in the entire weld metal, containing two intermetallic compounds (IMC) of Al2Cu and Al4Cu9 mainly in the Al side. In contrast, both elements hardly mixed each other in the 100 mm/s-105 A weld metal and the interface exhibited hook-like shape at a nearly constant pitch, depending on the welding speed and pulse frequency. Consequently, the formation of IMC layers was limited. Based on the three-dimensional images reconstructed using a serial sectioning technique, the hook-shaped Al/Cu interface was also formed inside the weld metal. The mixed-zone volume per unit weld length of the 100 mm/s-105 A joint was estimated to be about 0.12 mm3/mm, and is much smaller than that of the 50 mm/s-85 A joint (0.97 mm3/mm). The average tensile strength of the 100 mm/s-105 A joint were higher than those of the 50 mm/s-85 A joint, suggesting that the hook-shaped Al/Cu interface together with the reduced mixed zone seems to increase the joint strength.

Analysis of arc plasma characteristics and energy distribution in EDM based on two-temperature model

Arc plasma is the heat source in electrical discharge machining (EDM), it affects the material removal and discharge crater formation directly, so it is necessary to clarify its characteristics. However, it is challenging to understand the physical mechanisms behind each pulse discharge through experimental methods, as it is a transient, multi-physical process that occurs in a very short time and small gap. In this paper, a two-temperature model was proposed to investigate the characteristics of the arc plasma and the energy distribution considering the multi-physics fields in the steady state. In this model, the electrons and the heavy species of the arc plasma were considered separately in the energy conservation equations, so that the temperature of the electrons and heavy species can be calculated separately. Besides, the velocity distribution, pressure distribution, electrical potential distribution, and diameter of the arc plasma, as well as the heat flux distribution and the energy distribution into the anode and cathode were analyzed. Then the variations in arc plasma properties and energy distribution with different discharge conditions were studied. The results showed that, at a lower discharge current, the electron temperature was higher than the heavy species temperature, which means that the arc plasma did not reach a local thermodynamic equilibrium (LTE) state under these discharge conditions. To validate the simulation results, the arc plasma was observed with a high-speed camera, and the diameter of craters on the surface of both the cathode and anode was measured with single-pulse discharge experiments. The experiment results were consistent with the simulation results.

Physical characteristics of triple-wire gas indirect arc plasma

The triple-wire gas indirect arc welding (TW-GIA) has advantages of high deposition rate and low heat input. However, due to the lack of accurate understanding of the physical characteristics of arc plasma, the further development of this technology is restricted. In this paper, numerical simulation is used to quantitatively analyze the arc physical characteristics of TW-GIA. The results show that the TW-GIA consists of two separate arcs during the ignition stage, and then gradually couples into a single inverted cone arc. The arc temperature is symmetrical along the main wire. The current density of the stable arc is concentrated at the end of the three wires, and the maximum current density of the main wire end is 2.28–2.92 times that of the side wire. The magnetic field intensity at the symmetrical position along the main wire is in the opposite direction, and the values are basically the same. In the X-axis direction, the energy flow density presents an “M" type characteristic. In the Y-axis direction, as the distance from the main wire increases, the energy flow density first decreases sharply, then slowly increases, and then decreases. The measured arc morphology and electron temperature agree well with the calculated results.

Numerical investigations of arc plasma characteristic parameters evolution and metal properties in GMAW-based WAAM of Al alloy with an integrated model

Understanding the arc plasma characteristic parameters evolution and the metal thermodynamics is of great significance for guiding the improvement of the forming accuracy and performance of GMAW-based WAAM in engineering. In this study, we have developed a three-dimensional arc plasma-droplet-molten pool integrated model of GMAW-based WAAM of Al alloy, which simultaneously includes the heating of arc plasma, the vaporization of Al metal, the transfer of droplet, the melting and solidification of molten pool, and the relative motion between wire and substrate. Based on this sophisticated model, the effect of Al vapor on the arc plasma characteristics, the dynamic evolution of arc plasma characteristics during the metal transfer process, and the heat transfer and flow behaviors of liquid metal are comprehensively investigated. The simulation results show that the Al vapor is principally generated from the surface of droplet, which leads to the decrease of arc plasma temperature and arc pressure, and the expansion of current path. In a droplet transfer cycle, the average temperature of plasma decreases first and then increases, affected by the distribution of current density. Most of heat for the formation of molten pool comes from the energy transfer of droplet, and the droplet impact effect on the molten pool flow is significantly greater than Marangoni effect. Finally, the simulation results, including droplet transfer process and deposited layer profile, are validated by experimentally measured results, which are in good agreement with each other.

Deepening the understanding of arc characteristics and metal properties in GMAW-based WAAM with wire retraction via a multi-physics model

Wire retraction is used in the short-circuit droplet transfer mode of gas metal arc welding (GMAW) to improve the stability of transfer, reduce heat input and decrease spatter. The significant effects of wire retraction on the arc plasma characteristics and the thermal properties of the metal are not well understood. In this paper, we develop a three-dimensional, transient, multi-physics coupled GMAW model with wire retraction and apply it to wire arc additive manufacturing (WAAM) of an aluminum alloy. The model takes into account the wire's downward and upward motion, droplet growth and detachment, arc plasma heating, metal vaporization, melting and solidification of the molten pool, and the relative motion of the wire and substrate. The model is used to simulate the deposition of a single layer, and the evolution of the arc characteristics and the metal thermal and flow behavior are analyzed. The results demonstrate that during a wire motion period, the arc characteristics are determined by both the transient welding current and the distance between the welding wire and the molten pool. The arc plasma has a significant influence on the temperature and flow of the droplet and the molten pool metal when the wire is well separated from the melt pool and the welding current is in its peak phase. The energy and momentum of the metal in the molten pool are primarily influenced by the metal transfer, and the maximum flow velocity and maximum temperature occur at the time of the short-circuit contact. The results demonstrate the advantages of using a low welding current during droplet transfer, which is made possible by wire retraction. The model is validated by comparing the predicted morphology of the deposited layer and the shape of the arc during a wire motion period with experimental results, with reasonable agreement found.

Plasma characteristics of a novel coaxial laser-plasma hybrid welding of Ti alloy

A novel coaxial laser-plasma hybrid welding method defined as “laser-soft plasma coaxial hybrid welding” was developed and studied. The plasma characteristics evolution, including plasma morphology, static electrical characteristic, and physical information of this welding method, was studied with the based material of TC4 alloy. Laser welding and plasma welding were carried out and used as comparative experiments. The plasma morphology of hybrid welding combines the characteristics of laser-induced plasma and arc plasma. The static electrical characteristic indicates that laser and plasma interact and influence each other but with different mechanisms under different current conditions. Physical information such as plasma electron temperature and ion density show that composite plasma can rapidly increase the heat source energy and ionization rate. To sum up, the coaxial plasma arc can increase the laser effect and redistribute the heat of the compound heat source, leading to a widened bead weld and better welding gap adaptability. This work provides an effective method and reference for hybrid welding process design and control in the practical industry.

Effects of Pulse Interval on Forming Process in Wire Arc Metal Additive Manufacturing Using Pulsed Arc Plasma

To overcome the material processing challenges induced by high levels of heat input in wire arc additive manufacturing (WAAM), an innovative WAAM method using pulsed arc plasma (PAP-WAAM), was developed by the authors in the previous study. In this method, the PAP generated by the pulsed voltage was used as the heat source. The pulse interval can be defined as the time interval between adjacent pulse voltages, which determines the ignition time and frequency of the arc plasma, thus influencing the forming process. However, the effect of pulse interval on the forming process has not yet been revealed. Here, the effects of pulse interval on forming process during the PAP-WAAM of Ti6Al4V, including thermal behavior, arc plasma characteristics, and metal transfer process, were investigated by experiments and simulation. The results exhibited that the interpass temperature and maximum peak temperature decrease with increasing pulse interval at the same arc plasma power, indicating an alleviation of heat accumulation along the building direction. As the pulse interval increased, the ignition mode of the arc plasma changed from ignition between the tungsten electrode and the previously deposited layer to ignition between the tungsten electrode and filler wire, which increased the proportion of discharge energy allocated to the filler wire, thus reducing the overall heat input required for material deposition. When the pulse interval was 300 and 400 ms, only the uninterrupted bridging transfer mode was observed during the deposition process. The uninterrupted bridging transfer is considered to contribute to forming a smooth and consistent layer appearance. In addition, longer pulse intervals resulted in less surface oxidation, narrower wall thickness, and better macrostructure, attributed to reduced heat input and improved effective heat dissipation. This research reveals the effect of pulse interval on forming process during PAP-WAAM, which benefits the fabrication of desirable metal parts.

Strengthening of Al/Cu dissimilar joint due to complicated interface produced by pulsed TIG welding with a constricted nozzle

Al/Cu dissimilar joining is a key technology for weight reduction in fabricating high-functional products, however, conventional tungsten inert gas (TIG) welding is difficult to be applied due to a large fusion area. The constricted nozzle equipped inside the conventional TIG torch has been developed and can improve the position accuracy of tungsten electrode and arc plasma characteristics, moreover increase the heat input density. In this study, 0.5 mm-thick Al and Cu dissimilar sheets were butt welded using pulsed TIG welding with the constricted nozzle under two welding speed-current combinations of 50 mm/s-85 A and 100 mm/s-105 A. The 50 mm/s-85 A joint exhibited that Al and Cu mixed each other in the entire weld metal, containing two intermetallic compounds (IMC) of Al2Cu and Al4Cu9 mainly in the Al side. In contrast, both elements hardly mixed each other in the 100 mm/s-105 A weld metal and the interface exhibited hook-like shape at a nearly constant pitch, depending on the welding speed and pulse frequency. Consequently, the formation of IMC layers was limited. Based on the three-dimensional images reconstructed using a serial sectioning technique, the hook-shaped Al/Cu interface was also formed inside the weld metal. The mixed-zone volume per unit weld length of the 100 mm/s-105 A joint was estimated to be about 0.12 mm3/mm, and is much smaller than that of the 50 mm/s-85 A joint (0.97 mm3/mm). The average tensile strength of the 100 mm/s-105 A joint were higher than those of the 50 mm/s-85 A joint, suggesting that the hook-shaped Al/Cu interface together with the reduced mixed zone seems to increase the joint strength.

Investigation on surface morphology and microstructure of double-wire + arc additive manufactured aluminum alloys based on spectral analysis

Double-wire + arc additive manufacturing has gained increasing attention due to the advantage of controlling alloy composition in real time. However, the control mechanisms of microstructure and mechanical properties of high strength aluminum alloys have not been revealed. To solve this problem, in-situ monitoring of double-wire + arc additive manufacturing process were carried out by the spectrograph and a visual sensor. The spectral signal and arc plasma characteristics under different wire feeding rate ratios were systematically studied. Combined with the high-speed photography results of the droplet transfer, it was found that spectral intensities of Mg I 517.26 nm represented abnormally high during the globular transfer process. Surface bulges with the size of about 100 μm were detected. In addition, the microstructure and phase composition of the deposited parts were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results indicated that the variation of electron temperature was consistent with the variation trend of Al2CuMg phase content under different processes. The intensity ratio IRMn/Mg of spectral line Mn I 407.92 nm to Mg I 517.26 nm was proposed to quantitatively measure the degree of phase transformation, which had a better performance than the spectral line intensity and electron temperature. Under the conditions of this research, the phase composition was α(Al) + θ(Al2Cu) + S(Al2CuMg) three-phase when the IRMn/Mg fluctuated around 0.59, and α(Al) + S(Al2CuMg) two-phase produced when the IRMn/Mg fluctuated around 0.35.

Magnetohydrodynamic modeling and simulation of a vacuum arc plasma jet with a ring anode under different external magnetic fields

Supersonic plasma has been widely used. A vacuum arc ion source provides one possible method for generating supersonic plasma. An external magnetic field can effectively avoid the wall loss of the plasma in the ion source and improve the ion yield. In this work, a two-dimensional magnetohydrodynamic model is established, considering different components including ions and electrons. With the help of simulation, we explore the physical characteristics of the supersonic vacuum arc plasma formed from a copper disk cathode. The characteristics that we focus on include plasma composition, current density distribution, plasma velocity, and plasma temperature. These characteristics as well as the ion yield are compared when different magnetic fields generated by solenoids near the cathode are applied, as well as when the arc current is different. The results show that, in the absence of an external magnetic field, ions expand freely with the approximate axial velocity and average ion charge state. With the increase of external magnetic flux density, the wall loss of the plasma will decrease, and the axial velocity and average ion charge state will increase, but the magnetic saturation phenomenon exists. The simulation results are consistent with the experimental results.

Unified modeling and kinetic analysis of the near-cathode region and hot cathode in atmospheric-pressure arc discharges

The near-cathode region plays a crucial role in exploring the transport characteristics of the transition from arc column to the hot cathode in atmospheric-pressure arc discharges because of the existing non-equilibrium phenomena. A one-dimensional unified model, including the near-cathode region and the cathode body, is developed for an argon arc discharge with the tungsten cathode at atmospheric pressure in this paper. The electrostatic model coupled with an external circuit in the near-cathode region is solved based on the implicit particle-in-cell coupled Monte Carlo collision method without any assumptions of thermal or ionization equilibrium or quasi-neutrality. A detailed description of the arc plasma–cathode and cathode–gas interactions is obtained by calculating the nonlinear heat conduction equation in the cathode. It is shown that the space-charge sheath strongly affects particle transport in the near-cathode region and energy transport from arc plasma to the thermionic cathode. The total current density has significant effects on the kinetic characteristics of arc plasma by feedback-like mechanisms. The Joule heating by the external circuit and charged particles deposited into the cathode are dominating mechanisms of energy transfer from the near-cathode region to the cathode, while energy loss by radiation is more significant compared with natural convection.

Influence of plasma beam polishing process parameters on surface roughness of AISI 304 stainless steel

Industrial products used in medical equipment and food manufacture are usually made from AISI 304 and place great demands on surface polishing. The application of plasma beam in the field of energy beam polishing is a new technology to obtain a desired level of surface roughness. Therefore, this paper details an investigation conducted to focus on the effect of process parameters on the surface morphology of AISI 304 stainless steel during plasma beam polishing. The main arc current, nozzle height, scanning speed and plasma gas flux that have the greatest influence on the arc plasma characteristics and energy input values are considered to be the key experimental parameters. While the measured roughness values and their intensity autocorrelation functions are applied to evaluate the polished surfaces. The capacity of plasma beam polishing to produce glossy and defect-free surfaces on AISI 304 has been successfully verified. Under the specific combination of main arc current, nozzle height and scanning speed, the energy input could reach approx. 90 J/mm ∼ 110 J/mm, corresponding to the more than 85.9% fall in areal roughness Sa. Although the plasma gas flux had no discernible impact on the energy input, it was observed that the surface uniformity varied from 0.81 ± 0.01 μm Sa to 1.04 ± 0.04 μm Sa with the increase of plasma gas flux. Possible changes of chemical composition and nano-hardness during plasma beam polishing of AISI 304 stainless steel are analyzed.

Spatial distribution characteristics of vacuum arc plasma with occluded deuterium electrode

There are many kinds of ions in vacuum arc discharge plasma, which have different distributions in space. In this paper, a compact magnetic analyzer is developed for studying the spatial distribution of deuterium ions and metal ions in vacuum arc discharge with occluded deuterium electrode. When the arc current is about 100 A, the device can effectively transfer the ion beam with good secondary electron suppression, and can accurately obtain the ion current intensity. The spatial distribution of deuterium ions and titanium ions in the vacuum arc discharge with TiD electrode are measured by this device. The results show that both deuterium ions and Titanium ions are Gaussian distribution in the radial direction, but deuterium ions are evenly distributed, while titanium ions are relatively concentrated near the axis, resulting in the lowest proportion of deuterium ions near the axis. Along the axis, the number of all ions decreases as a natural exponential function, and the relative magnitudes are approximately equal, so the proportion of deuterium ions is almost constant. The results of this study not only help to understand the plasma expansion process of vacuum arc discharge, but also guide the design of vacuum arc ion source with occluded deuterium electrode and its ion extraction.

Improvement of penetration ability of heat source for 316 stainless steel welds produced by alternating magnetic field assisted laser-MIG hybrid welding

An alternating magnetic field was designed to increase weld depth of laser-MIG hybrid welded 316 stainless steel joint. The influencing mechanism of alternating magnetic field on improving penetration ability of hybrid heat source of laser-MIG hybrid welding was revealed. The results suggested that the difference of weld depth under different magnetic flux density was attributed to the change of characteristics of arc plasma and laser-induced plasma, droplet transition and keyhole behavior. More compressed arc shape under lower magnetic flux density (LMFD) with 20 m T and 30 m T promoted laser-induced plasma to move along the channel of laser beam, leading to decrease of weld depth. However, the laser-induced plasmas could be dispersed away from the channel of laser beam under higher magnetic flux density (HMFD) of 60 m T and 90 m T, which was the main reason for the increased penetration ability of hybrid heat source. Besides, the droplet transferred to behind the keyhole instead of dropping into the keyhole and more stable keyhole was obtained under HMFD, which were also beneficial for deeper penetration depth of laser energy. Moreover, the motion behavior of charged particles of arc plasma and laser-induced plasma and forces condition of droplet transition were discussed in magnetic field assisted laser-MIG hybrid welding.

Effect of Arc Currents on the Mechanical, High Temperature Oxidation and Corrosion Properties of CrSiN Nanocomposite Coatings

In methods for multi-arc ion plating technology, the behavior and characteristics of the arc spot determine the physical characteristics of arc plasma and the properties of the subsequent deposited coatings. In this paper, the effect of arc currents on the hardness, friction coefficient, high temperature oxidation, and corrosion properties of the CrSiN coatings was studied. According to the XRD and SEM results, with the increase of arc currents, the coatings grew preferentially to the CrN (111) crystal direction, and the CrN (220) crystal phase appeared at high currents of 90 A. In addition, the number of large particles increased when the current exceeded 70 A. The HR-TEM results confirmed the formation of nanocomposite structure of nanocrystalline of CrN embedded into the amorphous phase of Si3N4 as explored by XRD. The maximum hardness was achieved at 3120 Hv when the coatings were deposited under currents around 70 A. However, the hardness values decreased with further increase of arc currents. From the contact of ceramic balls with the wear of coatings, the surface of coatings gradually produced friction marks, and the friction force increased from a steady friction force to a dynamic friction force. The high temperature oxidation results showed that fewer oxides were formed on the surface of the coatings when oxidized at 800 °C. It was also found that CrSiN nanocomposite coatings prepared at an arc current of 70 A had a larger corrosion potential and polarization impedance, which could effectively protect the tool matrix.

Spatiotemporally resolved characteristics of arc plasma in non-thermal multi-arc generator at atmospheric pressure

The spatiotemporally resolved characteristics of arc plasma in a non-thermal multi-arc generator with three high-voltage electrodes and a common grounded one were investigated by means of arc current signal, discharge image signal, and image analysis. Experimental results show that the spatial distribution of multi-arc plasma can be adjusted by the gas flow rate, and multi-arc plasma tends to distribute in the center of the arc chamber with the decrease in the gas flow rate. Once the confluence of three independent arc columns occurs, a common arc root will be shared by three arcs. The common arc-root attachment varies between constricted state and diffuse state, and the variation duration was in a cycle of about 1 ms, which is associated with beat vibration caused by the small deviation among the frequencies of three arc currents. This phenomenon suggests that the size of the arc root attachment can be adjusted by means of the frequency of the driving power supply.

Analysis of Micro Arc Plasma Characteristics of the Mixed Metal Vapor in Vacuum Circuit Breaker

For the mechanical vacuum circuit breaker, the particle composition group of the metal vapor arc varies with different operating conditions, which will lead to the discontinuous variation of the electrical conductivity between electrodes. The change of mixed metal vapor arc macroscopic electrical characteristics results from the space-time change of microscopic arc plasma characteristics. For the vacuum circuit breaker, the interruption performance is directly influenced by the composition of the metal vapor arc plasma and the characteristic parameters. For evaluating the electrode characteristics and establishing a database of mixed metal vapor arc characteristic parameters for the vacuum interrupter, this paper presents a study of the copper chromium (CuCr) alloy contacts used in vacuum circuit breakers. The Eindhoven model was used to derive a Local Thermodynamic Equilibrium (LTE) vacuum arc plasma particle composition model. The thermodynamic parameter variation of metal vapor arc plasma is calculated by statistical thermodynamic method, and the electrical conductivity was calculated by Chapman-Enskog method. The mass density, enthalpy, specific heat and electrical conductivity for different alloy proportion (CuCr25, CuCr40, CuCr50, CuCr60 and CuCr75) were compared and quantitatively characterized.

Effect of Alternating Magnetic Field on Arc Plasma Characteristics and Droplet Transfer during Narrow Gap Laser-MIG Hybrid Welding

In this paper, the morphological characteristics of arc plasma and droplet transfer during the alternating magnetic field-assisted narrow gap groove laser-MIG (metal inert gas) hybrid welding process were investigated. The characteristics of arc plasma and droplet transfer, electron temperature, and density were analyzed using a high-speed camera and spectrum diagnosis. Our results revealed that the arc maintained a relatively stable state and rotated at a high speed to enhance the arc stiffness, and further improved the stability of the arc under the alternating magnetic field. The optimum magnetic field parameters in this experiment were B = 16 mT and f = 20 Hz, the electron temperature was 9893.6 K and the electron density was 0.99 × 1017 cm−3 near the bottom of the groove, which improved the temperature distribution inside the narrow gap groove and eliminated the lack of sidewall fusion defect. Compared to those without a magnetic field, the magnetic field could promote droplet transfer, the droplet diameter decreased by 17.6%, and the transition frequency increased by 23.5% (owing to the centrifugal force during droplet spinning and electromagnetic contraction force). The width of the weld bead was increased by 12.4% and the pores were also significantly reduced due to the stirring of the magnetic field on the molten pool.