The galvanized angle steel of galvanized angle steel manufacturers mainly adopts galvanic principle to prevent corrosion of galvanized coatings. Therefore, it is necessary to ensure that the zinc powder is in full contact with the steel to produce an electrode potential difference, so the surface treatment of steel is very important. Before spraying cold galvanizing, mechanical derusting (sandblasting, shot blasting, etc.) should be selected to make the surface cleanliness of the steel reach ISO85O1-1Sa2.5 level, equivalent to GB8923 Sa2.5 level. Its text definition is: "After the steel is mechanically derusted, the surface is free of oil, rust, oxide scale and other dirt, or only slight traces are left; 95% of the surface of the steel is impacted by steel shots (sand) and exposed The gloss of the metal. "
Galvanized angle steel manufacturers' galvanized angle steel is another indicator of surface treatment quality—roughness. Different cold galvanized materials have different requirements for roughness. In the construction instructions of Zinga, the average roughness Ra = 12.5 is required, that is, the roughness Rz = 55-75 microns. In the "Strong Zinc" and "Robaru" construction instructions, the requirements for roughness are slightly lower, Rz = 40 ~ 60 microns.
If the galvanized angle steel of the galvanized angle steel is formed into a film by cold galvanizing alone, the surface roughness can be controlled slightly smaller as an anticorrosive coating to ensure the thickness of the cold galvanized coating. When the thickness of the bottom layer of the coating is greater than 180 microns, in order to ensure the adhesion of the entire coating, the surface roughness Rz of the steel should be greater than 60 microns.
