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K-TIG welding is an exceptionally efficient welding technique that enables full penetration with a single pass, without the need for groove preparation or wire filling. Comprehending the distinct arc characteristics of K-TIG welding is crucial for exploring the metallurgical process, heat, and mass transfer, and serves as a guide for design considerations. In this study, 2D numerical models of arc plasma in K-TIG welding were established. The arc characteristics of the keyhole and non-penetrated states were compared, while the influence of welding parameters on arc characteristics was further investigated. Finally, the calculated arc pressure was validated by experiments. Results show that the electric potential gradient in the arc column decreases once the keyhole is formed. Simultaneously, the temperature increases at the center of the anode surface and decreases on both sides away from the arc center. Higher welding currents and smaller tungsten tip angles will lead to an increase in the temperature and velocity of arc plasma. As the tungsten tip height increases, the arc temperature increases on both sides but decreases in the arc center, and the pressure in the inner wall of the keyhole shrinks.

In laser and plasma arc compound heat source welding technology, we collected a series of comparative data for a full range of analyses. We proceeded with an in-depth discussion of these two welding technologies in terms of the weld penetration, the melted width, the shape and size of the weld, laser power, heat source spacing, and welding speed. After research, we found that during laser-arc hybrid welding, weld penetration is very sensitive to laser power and welding speed but relatively less sensitive to heat source spacing and welding speed.

Wire arc additive manufacturing (WAAM), also known as Arc-DED, possesses great potential for efficient production using various materials and wire types. This study utilized gas metal arc (GMA) and plasma transferred arc (PTA) variants of WAAM to deposit 2.25Cr-1Mo steel employing a metal-cored wire (MCW) and a solid wire counterpart having the same chemical composition for the comparative study. Initially, bead-on-plate trials were conducted with both WAAM processes and different shielding gas combinations in GMA-WAAM using the cored wire. The heat input versus deposition ratio was analysed to assess the heat input and the effects of shielding gases in GMA-WAAM. Arc behaviour was monitored with a process camera, and bead morphologies and dilutions were compared. Furthermore, test walls were deposited under the two WAAM processes and the shielding gas conditions, employing the cored and solid wire. Detailed microstructural study was conducted through optical microscopy, and hardness tests were performed to determine the mechanical properties. Energy dispersive X-ray spectroscopy (EDS) was used to examine the elemental composition and potential segregation in walls deposited with cored and solid wires. Results indicated a lower heat input when using cored wire and variable heat input due to shielding gases. A bainitic/martensitic microstructure was observed in test walls deposited with cored and solid wires with comparable microstructural features. The PTA process produced higher hardness than GMA, and solid wire exhibited slightly higher hardness than cored wire. Selection of shielding gas also influenced the hardness. Finally, the EDS maps and elemental study revealed comparable results for both wires. The results show good performance and outcome for cored wire.

Low-cost micromanufacturing technique for forming copper foils into desired micro-parts plays an important role in facilitating the widespread application of copper foil. Here, the pulsed arc plasma generated by the pulsed voltage was used as a heat source to achieve thermal stress–induced bending of copper foil in an electrical discharge machining (EDM) machine. Metallic foil with a thickness of 0.1 mm and a cylindrical rod with scanning motion were used for the first time as tool electrodes in the EDM bending of workpieces. The effect of various processing parameters, such as polarity, machining time, discharge current, duty factor, and discharge frequency, on the bending angle was investigated by optical microscopy. The main factors affecting the bending angle and their working mechanisms were analyzed in depth. Experimental results showed that the bending angle of the copper foil increases with the increase of the discharge energy, which was mainly attributed to the increasing thermal gradient along the thickness direction of the copper foil. When the copper foil was used as the anode, the carbon deposition phenomenon in the copper foil effectively reduced the material removal caused by the pulsed arc plasma, which contributes to the surface integrity and performance of the copper foil. Furthermore, several typical bend-formed parts, including curved, sawtooth, and S-shapes, were formed using pulsed arc plasma. This work proves that pulsed arc plasma is a reliable and cost-effective heat source for achieving thermal stress–induced bending of copper foil.

The heat of arc plasma is the primary energy source of the electric arc furnace (EAF) for high-titania slag smelting. A unified model of fluid flow, heat transfer, and arc-slag interaction is developed by taking magnetohydrodynamic (MHD) equations into account. The model is first validated by comparing the calculated results with the previous experimental data. The dynamic variations of the concavity of the molten pool surface are tracked by using the volume of fluid (VOF) model to investigate the interaction between the arc and the molten pool. Moreover, the model is applied to investigate the influence of slag viscosity and arc length on the flow behavior of the interface and the arc plasma characteristics. Based on the simulation results, the low viscosity and short arc length result in deeper and narrower concavity of the interface, which may lead to the splashing of molten slag and influence the stability of the arc. For cost savings and efficiency improvement, the position of electrodes and the temperature distribution in the EAF ought to be monitored and controlled to maintain proper arc length and viscosity during the production process.

In this study, both the plasma process of filtered laser-arc evaporation and the resulting properties of tetrahedral amorphous carbon coatings are investigated. The energy distribution of the plasma species and the arc spot dynamics during the arc evaporation are described. Different ta-C coatings are synthesized by varying the bias pulse time and temperature during deposition. An increase in hardness was observed with the increased overlapping of the bias and arc pulse times. External heating resulted in a significant loss of hardness. A strong discrepancy between the in-plane properties and the properties in the film normal direction was detected specifically for a medium temperature of 120 °C during deposition. Investigations using electron microscopy revealed that this strong anisotropy can be explained by the formation of nanocrystalline graphite areas and their orientation toward the film’s normal direction. This novel coating type differs from standard amorphous a-C and ta-C coatings and offers new possibilities for superior mechanical behavior due to its combination of a high hardness and low in-plane Young’s Modulus.

This research work presents the comparative analysis of heat input during aluminum welding focusing on FSW, Plasma-FSW, and TIG–FSW. This study aims to investigate their thermal behavior and temperature distributions during aluminum welding. With a specific emphasis on their thermal histories, peak temperatures, and simulated weld zones, the study elucidates the impact of auxiliary heat sources on heat input and material flow. A comparison of the heat input, heat dissipation, and heat output of these three welding techniques is necessary for analyzing their weld characteristics. In this research work, ABAQUS software was utilized to develop a computational model and numerical simulation for analyses the thermal aspect of each welding technique. Welding parameters such as heat generation by tool, preheating by auxiliary heat source (electric arc at 45 amp) and welding speed (63 mm/min) are considered to understand heat distribution within the weld zone are evaluated and compared to justify the improvement and development of FSW technique of discrete artefacts. The influence of auxiliary heat source by Plasma arc and TIG arc show improvement in thermal behavior of welding such as peak temperature achieved percentages between 50 and 55% of melting temperature of base metal as compare to FSW (44.4%), indicating enhanced plasticization due to the additional heat provided by preheating sources. However, plasma-FSW achieved higher peak temperature due to stable, higher arc efficiency and high-energy nature of plasma arc preheating which create improved preheating zone with higher temperature. Therefore, the auxiliary source preheating proved crucial for adjusting the characteristics of the plasticized material and regulating the heat input before the FSW process. These results open up new avenues for research in hybrid FSW and encourage efficiency and creativity in welding technology for a variety of industrial applications. They also offer insightful information on how variations in heat input impact thermal behaviour and weld characteristics.

Electric arcs are a necessary heat source in many industrial processes that take place in Submerged Arc Furnaces (SAFs). Arcs exhibit non-linear electrical characteristics and behave in a complex manner. Therefore, an improved understanding of their behavior enables better control of furnace operation. Modeling of industrial arcs is a multiphysics process that involves simultaneously solving several coupled physical phenomena, such as electromagnetics, fluid dynamics, and heat transfer, including a radiative heat transfer from the plasma arc. Coupling fluid dynamics and electromagnetics is known as Magnetohydrodynamics (MHD). For practical applications, however, there are also simpler approaches to arc modeling, either based on simplified physical principles or empirical behavior. In this paper, a combined Cassie–Mayr model (CMM) and a channel arc model (CAM) are implemented and coupled with a submerged arc furnace electrical circuit model. The complete circuit model parameters such as resistances and inductances are estimated using modeling of a full size furnace, and then, actual measurements from a SAF are used to validate the models by comparing current and voltage waveform. Both models are then used to estimate harmonic distortion in a SAF for different arc current ratios, which should help operators to estimate the arc current in real time thus be able to lower and raise the electrode to keep operating conditions constant.

The controlled pulse welding current combined with ultrasonic vibration was used to increase the keyholing/penetrating capability of plasma arc, and a mathematical model was developed to elucidate the underlying mechanism of periodic interaction between the ultrasound field and the plasma arc. The exerted ultrasonic vibration on the tungsten electrode increases the thermal conductivity of plasma arc, reduces the electrical conductivity of plasma arc, and then enhances the heat-pressure of plasma arc. The variations of the heat flux, current density, and the plasma arc pressure with time were quantitatively analyzed. Compared with the traditional controlled pulse plasma arc welding, the plasma arc heat flux, plasma arc pressure, and gas shear stress on the anode surface all increase in both peak and base stages of welding current after ultrasonic vibration is applied, which improves the keyholing/penetrating ability of plasma arc under the controlled pulse current. The experimental measurements were made to validate the numerical model indirectly.

Experimental investigation on controlled pulse keyholing plasma arc welding (PAW) assisted by ultrasonic vibration was carried out. Because of application of the ultrasonic vibration, the peak value of the pulse welding current was decreased by 7–20%, and the welding speed was increased by 17–27% with different base current durations, different current descent times, and different descending currents. It indicates that the ultrasonic vibration can make controlled pulse plasma arc welding achieve stable one-pulse-one-keyhole mode at a lower heat input and a faster welding speed. Under the same welding process parameters, the area of keyhole exit was increased by 38% and the deviation distance of keyhole exit was reduced by 34%. The above results prove that the ultrasonic vibration can reduce the average welding current and heat input, improve the welding efficiency, and enhance the keyholing ability of the plasma arc for controlled-pulse keyholing PAW.