Influence of welding position and parameters in orbital tig welding applied to low-carbon steel pipes

摘要

The most notable characteristic of Orbital TIG welding is the constant geometric profile of the tubes. In the context of orbital TIG welding of tubes with a large diameter and thick walls, the relationship between the welding position, the use of constant or pulsed current and also the value of the average current on the geometric characteristics of the beads obtained was studied. We deposited welds on SAE1020 carbon steel tubes, as well as taking macrographs of the cross-sections of the beads using optical microscopy. High-definition films were used to understand the behaviour of the weld pool in different welding positions. The geometric characteristics were quantified using macrographs and software, and the relationship between these characteristics and the above-mentioned variables were traced. In addition, an analysis of the microstructure of the samples was carried out, correlating with Vickers microhardness. It was concluded that the beads welded with pulsed current were more reinforced and wider, as well as being harder and having a finer microstructure. The vertical up position resulted in beads with a lower shape factor and more penetration, and the overhead position resulted in beads with a low shape factor.