The numerical model was developed using a SPH (Smoothed Particle Hydrodynamics) method and the projected transfer phenomena during a GMA (Gas Metal Arc) welding were simulated by the model to clarify mechanisms of the phenomena. As a result, the droplet transfer mode obtained from this calculation was regarded as a projected transfer mode in which the liquid column grew about 1 mm and a droplet grew up until its diameter became large the same as a wire diameter, after that it was detached from the tip of the column. In addition, 10 droplets were formed for 0.1 s through these growth and detachment processes at the tip of a wire. To compare with the numerical results, actual GMA welding was carried out and molten metal droplet transfers were taken by high speed camera. The diameter of a wire, the length of a liquid column, the velocity of a droplet right before it reached a weld pool obtained by simulation showed good agreement with experiment.
A molten metal droplet transfer processes were simulated by a numerical model using a three-dimensional smoothed particle hydrodynamics method in order to clarify the flux column formation mechanism at the tip of a wire during a flux cored arc welding process. This study focuses on the flux cored arc welding with TiO2 based wire. As a result, although the average droplet size obtained by the computation was larger than that by the experiment, the average length of the flux column obtained by the computation showed agreement with that by the experiment, which supports supported validity of this computational model. Moreover, the melting rate of the metal-pipe around flux was higher than flux. The flux column was formed at the tip of the wire. The simulations with different values of a specific heat and a thermal conductivity were performed to investigate the effect of the heat conduction in the wire on the flux column formation. The unmelted flux column was formed at the tip of the wire when the specific heat of the flux component was smaller and the thermal conductivity was higher than those of TiO2. The result indicated that the heat conduction in flux played an important role in the flux column formation during flux cored arc welding.
Behaviors of flux, slag and molten metal during a submerged arc welding with a large current were observed by the X-ray observation system including a high speed video camera. Moreover, the direct observation using a high speed video camera was also carried out to observe the arc phenomena, which could not be observed by the X-ray observation. From X-ray observation results, the weld part during a submerged arc welding was classified broadly into 4 regions. Then, it was clarified that a slag was pushed backward in a welding direction when it approached to a wire which an arc plasma existed around. As a result of this series of slag behaviors, the preformed cavity was filled by the slag at the backward of the heat source. In addition, from a direct observation, it was made clear that there were bluish white plasma at beneath a molten metal droplet and orange emitting region around the plasma.
In this study, the convective flow in a weld pool during a GMA welding process was clarified by a numerical simulation using an incompressible smoothed particle hydrodynamics method. The computational domain of this simulation was a two-dimensional vertical section of a base metal along the welding direction in a system whose consumable electrode moved. The simulation revealed that the molten metal droplet fell into the weld pool and generated a wave which travelled backward. When the wave hit the solid bead, it swelled up as it solidified generating a wavy surface, which is observed in actual GMA welding. The flow inside the weld pool was also simulated. Both the height of the formed reinforcement and the depth of the penetration agreed with experimental results, which presented the validity of this simulation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.