Cold Galvanized Angle Steel

The cold galvanizing process is used to protect metals from corrosion, utilizing a coating of zinc filler. It is applied to the protected surface using any coating method, and after drying, forms a zinc filler coating, which contains up to 95% zinc in the dry coating. Suitable for repair work (i.e., during the repair process, only areas with damage to the protected steel surface can be repainted as long as the surface is repaired). The cold galvanizing process is used for anti-corrosion of various steel products and structures.
Cold galvanized coatings mainly use electrochemical principles for corrosion prevention, so it is necessary to ensure sufficient contact between zinc powder and steel, resulting in electrode potential difference. Therefore, steel surface treatment is very important. Before spraying cold galvanizing, mechanical rust removal (sandblasting, shot blasting, etc.) should be selected to ensure that the cleanliness of the steel surface reaches ISO 85O1-1 Sa 2.5 level, equivalent to GB 8923 Sa 2.5 level. Its textual definition is: "After mechanical rust removal, the surface of steel is free of oil, rust, oxide skin, and other dirt, or only leaves slight marks; 95% of the steel surface is impacted by steel shot (sand), revealing the luster of the metal
For another indicator of surface treatment quality - roughness, different cold galvanized materials have different requirements for roughness. In the construction instructions for Zinga, it is required that the average roughness Ra=12.5, that is, the roughness Rz=55-75 microns. In the "Strong Zinc" and "Lobaru" construction instructions, the requirement for roughness is slightly lower, Rz=40-60 microns.
If cold galvanizing is separately coated as an anti-corrosion coating, the surface roughness can be controlled slightly to ensure the coating thickness of cold galvanizing; When cold galvanizing is used as the bottom layer of heavy-duty anti-corrosion coating, and the total supporting coating thickness is greater than 180 microns, to ensure the adhesion of the entire coating, the surface roughness Rz of the steel should be greater than 60 microns.