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Hot-dip galvanizing after welding

Source:    Time: 2016-12-23

1. General guidelines
Production and processing or hot-dip galvanizing of the entire steel component, in some cases is often impossible, especially for those bulky components using integral hot-dip galvanizing is problematic. In addition, component parts of hot-dip galvanized parts, or semi-finished products of hot-dip galvanizing, are sometimes required to be soldered on site.

Hot-dip galvanized steel and non-hot-dip galvanized steel, compared with the welding method used is basically the same. Basic research shows that, for the commonly used steel, the state of welding compared with the non-welded state, its hot-dip galvanized in the mechanical properties of the impact is not obvious. In the hot-dip galvanized steel welding method, manual arc welding is the most commonly used method. Gas welding is mainly suitable for the thickness of 3mm hot-dip galvanized steel sheet welding, but compared with the shortcomings of arc welding is the side of the weld surface of the galvanized layer to burn a little wider. For thicker plates, manual arc welding is preferred.

2.Welding practice
Because the welding process will produce high temperatures, so the two sides of the zinc coating layer is easy to burn or evaporate, which will affect the welding process. Therefore, compared with the welding of non-hot-dip galvanized steel, hot-dip galvanized steel welding process parameters need to be adjusted. The white vapor of zinc oxide generated during the welding process blocks the line of sight, making the welding operation difficult and complicated, resulting in sparking and unstable welding processes. In such a poor operating environment, the weld is easy to produce pores.
If necessary, hot-dip galvanized steel can also provide high-quality welds in many applications without compromising the mechanical properties of the steel components.

1) When the butt joints are welded, the spacing between the webs is slightly larger than that of the non-hot dip galvanized steel, which helps to remove the evaporated zinc and helps to prevent stomatal formation. The same applies to fillet welds.
2) The welding speed and welding process on the quality of a greater impact. Welding speed is too high, zinc vapor can not escape from the weld, and easy to penetrate the molten pool and welding slag. Reducing the welding speed and gently swinging the electrode facilitates the evaporation of zinc and the dissipation of zinc vapor.
3) As mentioned earlier, the evaporation of zinc will interfere with the welding arc, so a slight increase in welding current will have a beneficial effect. The evaporation of the zinc is easier because the welding current is increased to make the welding arc more stable.
4) Select the appropriate electrode for hot-dip galvanized steel welding is very important. If the electrode is capable of producing a slow-setting weld slag during welding, it will be suitable for the hot-dip galvanized steel welding since the slow solidification of the slag provides sufficient time for the zinc to escape from the weld pool.
5) When hot dip galvanized steel is vaporized, the steam containing zinc oxide should be removed in time to avoid damage to the health of the welding workers. A vacuum cleaner or a dust cover is a convenient commercial device