At the beginning of welding, the welding wire and the welding groove are short-circuited to start the arc, and a small amount of solid flux is continuously added, which is melted by the heat of the arc to form liquid slag. When the slag reaches a certain depth, the feeding speed of the welding wire is increased, the voltage is reduced, the welding wire is inserted into the slag pool, and the arc is extinguished, thus switching to the electroslag welding process.
Extended data:
During electroslag welding, the current mainly flows from the end of welding wire or plate through the slag pool to the metal molten pool, and the current field is conical, which is the main hot spot of electroslag welding. The function of conical flow field is to cause convection in the slag pool, bring heat to both sides of the bottom of the slag pool, and make the base metal form a concave melting zone. The temperature of slag pool in electroslag welding can reach 1600~2000℃.
In the welding process, if the atmosphere is in direct contact with the high-temperature molten pool, the oxygen in the atmosphere will oxidize metals and various alloy elements. Nitrogen and water vapor in the atmosphere enter the molten pool, and defects such as porosity, slag inclusion and cracks will also be formed in the weld during the subsequent cooling process, which will worsen the quality and performance of the weld.
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