1. Need to polish in the early stage

However, the galvanized layer of the weld must be polished away, otherwise bubbles, trachoma, and false welding will occur. It also makes the weld brittle and the rigidity decreases.

2. the welding characteristics of galvanized steel

Zinc has a melting point of 419 ° C and a boiling point of about 908 ° C. Zinc has a large solid solubility in iron, zinc liquid will deeply etch the weld metal along the grain boundary, and low melting point zinc forms “liquid metal embrittlement”.

If weld fillet welds, especially fillet welds of T-joints, are most susceptible to penetration cracks. For the penetration, the groove size should be appropriate, generally 60~65°, to leave a certain gap, generally 1.5~2.5mm; in order to reduce the penetration of zinc into the weld, the galvanized inside the groove can be welded before welding When welding the fillet weld, the zinc layer is also melted as much as possible in the first layer and vaporized and evaporated to escape the weld. The method is to first move the end of the electrode forward about 5~7 mm, when the zinc layer is made. In the case of cross-welding and vertical welding, if short-slag welding rods such as J427 are used, the tendency of undercutting will be small; if the round-trip transportation technology is used, the quality of non-defective welding can be obtained.