Four Differences Between Hot And Cold Galvanizing Of Square Rectangular Tubes

Galvanized square rectangular tube is a hollow square tube with a square cross-section shape and size made of a hot-rolled or cold-rolled galvanized strip or galvanized coil as a blank after cold bending and then high-frequency welding. Sectional steel pipe. Or a galvanized square tube made by hot-dip galvanizing the pre-made cold-formed hollow steel pipe.

Galvanized rectangular tubes are divided into hot-dip galvanized tubes and cold-dip galvanized tubes in terms of the production process. Due to the different processing methods of these two galvanized tubes, they have different physical and chemical properties. In general, their differences are mainly in terms of strength, toughness, and mechanical properties.

(1) Strength

The hot-dip galvanized square tube is welded after the use of steel plates or steel strips, and on this basis, the square tube is placed in the hot-dip galvanizing pool and undergoes a series of chemical reactions to form a tube. The production process of hot-dip galvanized pipe is relatively simple, but the production efficiency is very high, and there are many varieties and specifications, but this rectangular pipe requires very little equipment and capital and is suitable for the production of small galvanized rectangular pipe manufacturers. But in terms of strength, the strength of this steel pipe is far lower than that of seamless rectangular pipes.

(2) Corrosion resistance

 The cold-dip galvanized square tube uses the principle of cold-dip galvanizing on the used pipes to make it anti-corrosion. Different from hot-dip galvanizing, cold-dip galvanizing mainly uses electrochemical principles to carry out anti-corrosion, so it is necessary to ensure sufficient contact between zinc powder and steel to generate electrode potential difference, so the surface treatment of steel is very important.

(3) Surface treatment

The surface of the zinc layer of the cold-dip galvanized square tube is very smooth and dense, the structure is uniform, it has good mechanical properties and corrosion resistance, and the zinc consumption is 60%-75% lower than that of hot-dip galvanizing. Electro galvanizing is technically complex, but it must be used for single-sided coatings, double-sided coatings with different thicknesses on the inner and outer surfaces, and thin-walled pipe galvanizing.

(4) Process method

There are the wet method, dry method, lead-zinc method, redox method, and so on. The main difference between different hot-dip galvanizing methods is the method used to activate the surface of the pipe body to improve the quality of galvanizing after the steel pipe is pickled and cleaned. The current production mainly adopts the dry method and redox method.