|20.6.2019||Posted by juniperqq under Advertising & Marketing|
GI steel coil with spangles is prone to crack before welding, why such a situation occurs, so we must first understand the cause of crack to find the cause, in order to prevent the occurrence of accidents.
Under the action of arc heat, the zinc layer near the groove of the galvanized coil produces oxidation (ZnO) and evaporation and volatilizes out white smoke and steam, so it is easy to cause pores in the welding seam. The greater the welding current is, the more serious the evaporation of zinc is, and the greater the stomatal sensitivity is. When welding with titanium type and titanium calcium type electrode, it is not easy to produce pores in the medium current range. When using cellulose type and low hydrogen type welding rod welding, small current, and large current are easy to produce pores. In addition, welding rod Angle should be controlled as far as possible in the range of 30° ~ 70°.
Secondly, when GI steel coil with spangles is welded by arc welding, the zinc layer near the molten pool oxidizes into ZnO and evaporates under the action of arc heat, forming a large amount of soot. So good ventilation measures must be taken. Under the same welding specification, the amount of smoke produced by titanium oxide welding rod is lower, while the amount of smoke produced by a low-hydrogen welding rod is larger.
At last, the welding current of the GI steel coil is relatively small, and the ZnO formed in the heating process is not easy to escape, easy to cause ZnO slag inclusion. ZnO is stable and it’s melting point is 1800℃. Large block ZnO slag has a very unfavorable effect on weld plasticity. When using titanium oxide electrode, ZnO is small and evenly distributed, which has little effect on plasticity and tensile strength. When using cellulose or hydrogen electrode, the weld ZnO is larger and more, the weld performance is poor.