In addition, backing weld has a saying on ceramics that in single-sided welding with ceramic gasket, the first welding on ceramic gasket is also called backing weld.
CO2 gas shielded welding cannot be used in backing weld. Backing weld is the most critical place in multi-layer welding, which can only be achieved by the most reliable method. When carbon dioxide gas shielded welding is used, the porosity will become larger, and the existence of porosity in the welding gap will directly affect the weld quality.
Extended data:
Backing weld is the key link of multi-layer and multi-pass welding of medium and heavy plate, which has a vital influence on the joint performance.
Causes of welding contact bottom
1 to prevent angular deformation or
2. To prevent burn-through during automatic welding.
Matters needing attention in welding
1, control welding heat. If the welding speed is too slow or the welding current is too large, it will lead to overheating due to the long time of heat concentration at the weld. At this time, the outer surface of the weld is blue and the back is granular. Overburning is light.
2, argon protection. Tubes with complex alloy composition, especially when the chromium content is high (such as Fl2 steel), are easy to be burned. In the welding process, with the melting of the blunt edge of the groove, the weld appears different degrees of burn, and the back of the weld is poorly formed, rough and granular.