Cold galvanized Angle steel


Cold galvanized Angle steel

Cold galvanizing process is used to protect the metal from corrosion. For this purpose, the coating of zinc filler is used, which is coated on the protected surface by any coating method. After drying, the zinc filler coating is formed, and the content of zinc in the dry coating reaches 95%. Suitable for repair work (i.e. during repair work, only in the protected steel surface damage, as long as the surface is repaired can be re-coated). Cold galvanizing process is used for anticorrosion of various steel products and structures.

Cold galvanized coating is mainly anticorrosive through electrochemical principle, so it is necessary to ensure that zinc powder and steel fully contact, electrode potential difference, so the steel surface treatment is very important. Before spraying cold galvanized, mechanical rust removal (sandblasting, shot blasting, etc.) should be selected to make the steel surface cleanliness reach ISO 85O1-1 Sa 2.5 level, equivalent to GB 8923 Sa 2.5 level. Its text defines: "Steel after mechanical rust removal, the surface of no oil, no rust, no oxide and other dirt, or only leave a slight trace; Ninety-five percent of the steel surface is impacted by the steel shot (sand), exposing the metallic luster."

Roughness is another index of surface treatment quality, different cold galvanized materials have different requirements for roughness. In the construction instructions of Zinga, the average roughness Ra=12.5, that is, roughness Rz=55 ~ 75 microns. In "strong zinc" and "Robaru" construction instructions, the roughness requirements are slightly lower, Rz=40~60 microns.

If the cold galvanized film separately, as an anti-corrosion coating, the surface roughness can be controlled slightly smaller to ensure the thickness of the cold galvanized coating; When cold galvanized as the bottom layer of heavy anticorrosive coating, the total supporting coating thickness is greater than 180 microns, in order to ensure the adhesion of the entire coating, steel surface roughness Rz should be greater than 60 microns.

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