Hot dip galvanized and cold galvanized difference is as follows:
1, hot dip galvanized as metal anti-corrosion way, it will usually
be around 500 ℃ derusting processing steel structure in liquid
zinc, zinc layer on the surface of steel structure. Cold
galvanizing is through electrolysis adhered on the surface of the
metal material such as a layer of metal film, make the material
surface texture is uniform and anticorrosive wear-resisting,
external appearance more beautiful.
2, hot dip galvanized coating thicker, generally for 30 to 60
micrometers, coating anticorrosion ability is higher. Suitable for
outdoor work steel parts, such as highway fence, power tower,
large-sized fasteners such as relatively long-term rust "rough"
artifacts. Cold galvanizing, surface smooth level off, but because
of the coating is thin, within 5-30 micron, so the corrosion time
is short. Are used in indoor use the rust parts, such as the bottom
of the chassis, panels, small specification fasteners, etc.
3, hot dipped galvanized by the principle of atmospheric corrosion
resistant zinc, electrochemical protection, the material such as
iron and steel for zinc carbonate on the surface of the protective
film can slow down the corrosion rate, even if broken, will form of
zinc film layer again. Cold galvanizing is to use chemical ways,
separating the zinc alloy into zinc ions, has attached on the steel
surface, this way to form new layer is thinner, the iron and steel
in the general case, prone to rust.
4, cold galvanized surface is smooth, bright, colorful passivation
technology of galvanized coating can present yellowish green, white
passivation technology of plating can present bluish white, usually
only a small amount of zinc layer on both ends of the steel tube of
cold galvanization, there is no galvanized layer in the farther.
Galvanized surface is rough, the color is darker, like silver,
because the production process leads to surface have some lines and
water drops of tumor, the surface light, nor reflection. Hot dip
galvanized steel pipe internal and external are complete galvanized
layer.
