Factors Influencing Corrosion Resistance of Large Diameter Rectangular Tubes

The performance of large diameter rectangular tube

1. Corrosion resistance of large-diameter rectangular tubes. The large diameter rectangular tube actually makes the molten metal react with the iron matrix to produce an alloy layer, so that the matrix and the coating can be combined with each other. First pickle the rectangular tube. In order to remove the iron oxide on the surface of the rectangular tube, after pickling, it is cleaned in a tank of ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to into the hot dip coating bath. This will make the rectangular tube have a very uniform coating, strong adhesion, and long service life. In addition, the matrix of the large-diameter rectangular tube undergoes complex physical and chemical reactions with the molten plating solution to form a corrosion-resistant zinc-iron alloy layer with a compact structure, and the alloy layer is integrated with the pure zinc layer and the matrix of the rectangular tube. Therefore, its corrosion resistance is very strong.

2. The uniformity of the surface of the large-diameter rectangular tube. The rectangular tube sample is continuously dipped in copper sulfate solution for 5 times and will not turn red (copper-plated color). Small rough surfaces and localized zinc tumors are present. Coating weight: according to the requirements of the buyer, the rectangular tube can be used for the weight measurement of the zinc layer, and the average value shall not be less than 500g/m², and any sample shall not be less than 480g/m². Nowadays, the iron tubes used for gas, greenhouses and heating are also rectangular tubes. The rectangular tubes are used as water tubes, and a large amount of rust is easily generated in the tubes. The outflowing yellow water not only pollutes the sanitary ware, but also is mixed with bacteria that breed on the uneven inner wall, and the rust causes heavy metals in the water. Excessive content can seriously endanger human health.

Factors affecting corrosion resistance of large diameter rectangular tubes

1. Corrosion of chloride ions

Chloride ion is one more example that exists in nature and is present in various places such as salt, sweat, seawater, soil, etc.

Although large-diameter rectangular tubes have good corrosion resistance, in an environment with a large amount of chloride ions, the corrosion performance is relatively weak, resulting in rust. Therefore, the use of large-diameter rectangular tubes has environmental requirements and cannot be used in environments containing a large amount of chloride ions.

2. No solution treatment

Generally, large-diameter rectangular tubes contain other metal alloying elements in addition to carbon elements. At present, the most alloying elements in stainless steel are nickel, manganese, chromium and so on. The increase of these metal elements will improve the various properties of stainless steel, but if solution treatment is not carried out, the content of the alloy in the matrix structure will be low, and the corrosion resistance will be poor, so it will be corroded by the corrosion factors in the environment.

3. Innate intergranular corrosion

Materials free of titanium and niobium have a tendency to intergranular corrosion. At present, the vast majority of stainless steel materials in my country are without the addition of titanium and niobium. Although the surface of the large-diameter rectangular tube is not likely to be corroded, the inside of the tube begins to corrode. At the same time, during processing, certain behaviors can also accelerate intergranular corrosion, such as welding.

Large-diameter rectangular tubes are widely used in construction, machinery manufacturing, steel construction projects, shipbuilding, solar power brackets, steel structure engineering, power engineering, power plants, agricultural and chemical machinery, glass curtain walls, automobile chassis, airports, etc. In order to achieve the durability of the large-diameter rectangular tube, the above factors affecting the corrosion resistance must be avoided and the processing should be standardized.