The zinc layer near the groove of the color-coated plate is oxidized (formed ZnO) and evaporated under the action of arc heat, and volatilizes white smoke and steam, so it is easy to cause pores in the weld. The greater the welding current, the more serious the evaporation of zinc, and the greater the stomatal sensitivity. When welding with titanium type and titanium calcium type electrodes, it is not easy to generate pores in the medium current range. When welding with cellulose-type and low-hydrogen-type electrodes, pores are easily generated under both small current and high current. In addition, the angle of the electrode should be controlled within the range of 30° to 70° as far as possible.
Secondly, when the color-coated plate is welded by arc welding, the zinc layer near the molten pool is oxidized to ZnO and evaporated under the action of the arc heat, forming a large amount of smoke and dust. Therefore, good ventilation measures must be taken. Under the same welding specification, the amount of smoke and dust generated when welding with titanium oxide type electrode is lower, while the amount of smoke and dust generated when welding with low-hydrogen type electrode is larger.
Finally, when the welding current of the color-coated plate is small, the ZnO formed during the heating process is not easy to escape, and it is easy to cause ZnO slag inclusion. ZnO is relatively stable with a melting point of 1800°C. The bulky ZnO slag has a very adverse effect on the weld plasticity. When using titanium oxide type electrode, ZnO is finely and evenly distributed, and has little effect on plasticity and tensile strength. When using cellulose-type or hydrogen-type electrodes, the ZnO in the weld is larger and more, and the weld performance is poor.
