Research On Metal Transfer And Weld Formation Of MAG Welding Process With Strip Electrodes

The MAG welding process with strip electrodes is a kind of high-efficient method of MAG welding. Instead of the typical round wires, this technique makes use of flat wires with various dimensions. The technique provides high deposition and high welding speed. This article mainly uses the 0.4×5mm and 0.2×6mm strip electrodes to make deep research on arc characteristic, arc shape, metal transfer and appearance of weld characteristics.Firstly, the experiment platform which is used for the research of MAG welding process with strip electrodes has been established, including experiment system, electric current voltage signal collecting system and high-speed camera system. In this experiment platform, the welding torch is the most important part, which was designed and developed by myself. In particular the flat electrode holder is designed, which is used to ensure a smooth delivery of strip electrodes and a smooth striking arc. Results show that the design of strip electrodes torch meets the experimental requirements.In this study, a high-speed camera with appropriate dimmer is positioned to take the arc shape. The arc is the end of several arcs coupled. It moves around the end of strip electrodes and changes periodically with time. The front arc shape of strip electrodes is half ellipsoid, the arc gradient from the anode to the cathode is very small. However, the shape of side arc is tapered. Strip electrodes feed rate and arc voltage influence the arc shape of the MAG welding process with strip electrodes.In the study, a high-speed camera with the xenon lamp light source for the backlight is positioned to record the metal transfer. In order to measure the current and voltage of the MAG welding process with strip electrodes, a electric current voltage signal collecting system is installed. The results show that, the different metal transfer types of MAG welding process with strip electrodes are obtained, including short circuiting transfer, globular transfer, projected transfer and rotating streaming transfer. The projected transfer is proved to be the most optimal mode comparing with arc stability, weld appearance and weld penetration under the experimental conditions, which is suited by a very large presented range. Metal transfer is mainly affected by strip electrodes feed rate, arc voltage and the size of strip electrodes. With the increasing of strip electrodes feed rate, the metal transfer mode is changed. With the increasing of arc voltage, the transition frequency increased, and the droplet becomes small.Research on the resurfacing welding process shows that the MAG welding process with strip electrodes can avoid the finger penetration and undercut defections effectively in high current region due to the low current density and the low arc pressure, so that the deposition rate is increased greatly. It also can be seen from the result of experiments that the penetration and weld width become big with the increase of strip electrodes feed rate, and also the weld width and form factor become big with the increase of the arc voltage. Compared with round-wire electrodes MAG welding, its weld width, form factor of weld and deposition rate increase, the rate of dilution reduces. At last, a large number of experiments are done to get the best welding parameters of several kinds of strip electrodes under the current conditions.