Commonly used welding methods for steel structures are arc welding, including manual arc welding, automatic or semi-automatic arc welding, and gas shielded welding.
Manual arc welding is the most commonly used welding method in steel structures, and its equipment is simple and flexible. However, the labor conditions are poor, the production efficiency is lower than the automatic or semi-automatic welding, and the variability of the weld quality is large, which depends to some extent on the technical level of the welder.
The weld quality of automatic welding is stable, the internal defects of the weld are less, the plasticity is good, the impact toughness is good, and it is suitable for welding long direct welds. Semi-automatic welding is suitable for welding curves or welds of any shape due to manual operation. Automatic and semi-automatic welding shall be carried out with welding wire and flux compatible with the main metal. The welding wire shall comply with the national standards and the flux shall be determined according to the welding process requirements.
Gas shielded welding uses inert gas (or CO2) gas as a protective medium for the arc to isolate the molten metal from the air to keep the welding process stable. Gas shielded arc heating is concentrated, the welding speed is fast, and the penetration depth is large, so the weld strength is higher than that of manual welding. It has good plasticity and corrosion resistance and is suitable for welding thick steel plates.