galvanized steel surface with zinc oxide layer, so even very thin, also can achieve excellent corrosion resistance and high strength. however, these features for need welding galvanized steel, metal forming, is also a great challenge.
electric welding, gas wqualified, and approved by professional security technology study, the training and examination qualified, to receive the special type of work operation certificate and is able to operate independently.
any metal surface in the air environment will be oxygen or other oxygen gas of different degrees of chemical etching, the surface state of metals in nature are not pure state of sheet metal. therefore,
strong oxidation ability aluminum easy to combine with oxygen in air to generate dense solid al2o3 thin film, the thickness of about 0.1 microns. al2o3 as high as 2050 ℃, melting point than aluminium and aluminium