Galvanized square pipe is a hollow square cross-section steel pipe with a square cross-section shape and size made from hot-rolled or cold-rolled galvanized strip steel or galvanized coil plate, which is formed by cold bending and then high-frequency welding , or galvanized square rectangular pipes made by hot-dip galvanizing the pre-made cold-formed hollow steel pipes.
【Classification】
Galvanized square tubes are divided into hot-dip galvanized square tubes and cold-dip galvanized square tubes in terms of production technology. It is precisely because of the different processing of these two galvanized square tubes that they have many different physical and chemical properties. Generally speaking, they have many differences in strength, toughness and mechanical properties.
Hot-dip galvanized square tube: It is a square tube made by welding a steel plate or steel strip after being curled and formed. On the basis of this square tube, the square tube is placed in a hot-dip galvanizing pool and undergoes a series of chemical reactions. A square tube formed. The production process of hot-dip galvanized square tubes is relatively simple, the production efficiency is very high, and there are many varieties and specifications. This kind of square tubes requires very little equipment and funds, and is suitable for the production of small galvanized square tube manufacturers. However, in terms of strength, the strength of this steel pipe is far lower than that of seamless square pipes.
Cold-dip galvanized square tube: Cold-dip galvanized square tube uses the principle of cold galvanizing to make the square tube anti-corrosion. Different from hot-dip galvanizing, cold-dip galvanizing coating mainly uses electrochemical principles for anti-corrosion. Therefore, it is necessary to ensure full contact between zinc powder and steel to generate an electrode potential difference, so surface treatment of steel is very important.
[The difference between hot and cold galvanizing]
Galvanized square tubes are divided into two categories: hot-dip galvanized square tubes and electro-galvanized square tubes. Hot-dip galvanized square pipes include wet method, dry method, lead-zinc method, redox method, etc. The main difference between different hot-dip galvanizing methods is the method used to activate the surface of the pipe body to improve the galvanizing quality after acid leaching cleaning of the steel pipe. Dry method and redox method are mainly used in current production, and their characteristics are shown in the table. The surface of the zinc layer of electro-galvanizing is very smooth, dense and uniform in structure; it has good mechanical properties and corrosion resistance; the zinc consumption is 60% to 75% lower than that of hot-dip galvanizing. Electro-galvanizing is technically complex, but this method must be used for single-sided coatings, double-sided coatings with different coating thicknesses on the inner and outer surfaces, and thin-walled pipe galvanizing.
【use】
Since galvanized square tubes are galvanized on square tubes, the application range of galvanized square tubes has been greatly expanded compared to square tubes. It is mainly used in curtain walls, construction, machinery manufacturing, steel construction projects, shipbuilding, solar power generation brackets, steel structure engineering, power engineering, power plants, agricultural and chemical machinery, glass curtain walls, automobile chassis, airports, etc.
【characteristic】
Galvanizing has stronger protective effect and strong corrosion resistance. The entire structure is made of zinc, forming a dense quaternary crystal. This crystal forms a barrier on the steel plate, thus effectively preventing corrosion factors from penetrating. Corrosion resistance comes from the strong protective barrier layer of zinc. When zinc provides sacrificial protection on trimmed edges, scratches, and scratched parts of the coating, the zinc forms an insoluble oxide layer and plays a barrier protective function.