Why does the zinc-iron alloy non-standard door not rust?

"Do a good job of the door, the board is the key". High-speed guardrail why all day long wind and rain, but can do decades without decay, the key is the use of high-quality galvanized steel.

So why is it that an ordinary security door will rust after just two or three years?
The material surface of the high-speed guardrail is plated with a layer of anti-oxidation zinc, which blocks its oxidation road, so that the galvanized sheet is difficult to oxidize, so it will not rust. Later, the hot galvanized sheet was improved into what we now often say is zinc-iron alloy. The surface of the modified zinc-iron alloy has lost its beautiful zinc flowers and luster, and presents a silvery white or dark gray appearance, which is generally dark gray. The treated galvanized layer can carry out more complex bending forming process, and has good weldability, coating property, deep drawing property, heat resistance, corrosion resistance and other excellent properties.

Advantage 1: Good weldability Ordinary galvanized sheet in welding, because the zinc layer is easy to volatilize, zinc steam will produce pollution gas on the click, increase the current intensity, and prone to weld fracture, so seriously affect the welding quality. The hot galvanized plate after alloying treatment, because there is a pure zinc layer in the middle of the zinc layer, and because of the increase of iron content, the volatilization of zinc vapor is reduced, so that it has good welding performance, suitable for welding, spot welding, arc welding, carbon dioxide gas welding and other welding methods.

Advantage 2: Good coating performance Because the galvanized sheet in the hands of the user have to go through subsequent painting and other processes to increase the beauty of the material and corrosion resistance, the surface of the ordinary galvanized sheet is smooth, if you need to increase a certain degree of roughness, often through the smoothing process, the way can not provide a stable rough surface, affecting the coating performance. After alloying hot dip galvanized products, zinc alloy directly into the iron layer inside, so that the surface is relatively rough, under the microscope can see the surface of the coating uneven, there are micro porosity and holes, some places have micro cracks throughout the thickness of the coating direction. According to the meshing principle, this hemp surface structure can make the coating obtain good surface adhesion, thus improving the overall effect of painting.

Advantage 3: Good heat resistance The melting point of pure zinc is 419°, so at a temperature higher than that, the galvanized layer will lose its effect, and the melting point of zinc alloy reaches 640°, close to the melting point of pure aluminum, and the heat resistance is good, so that the oxidation resistance of iron plate has been continued.

Advantage 4: Good corrosion resistance Ordinary galvanized products in a humid environment, easy to occur zinc layer clothing, white rust and then affect the appearance of the surface of galvanized products and its service life. After alloying hot dip galvanized products, the surface can obtain a layer of thick, very fine, and not dissolved in water dark gray inactive oxide film, it can prevent the oxidation of respect does not occur, while the zinc alloy layer of the standard electrode between iron and pure zinc layer, it is more active than iron, but slower than pure zinc layer, so the electrochemical corrosion is slower than pure zinc layer.

Advantage 5: Good deep drawing weight is lighter than galvanized sheet, but mechanical properties such as tensile strength, yield, elongation than ordinary galvanized sheet is better. Deep drawing performance and surface to hard objects pressed into or friction caused by plastic deformation has a stronger resistance, in addition to excellent durability and strength, it also has flexibility and resilience, can be flexible processing, to achieve the sheet metal designers required by the construction form. High-grade automotive materials, flatness up to 99%
Zinc alloy is another product separated from the main protective coating of steel material, is a pollution-free environmental protection material, and can also be 100% recycled. Flatness of 99% of the advantages of high-quality products, the world's most used automotive steel plate is zinc alloy plate.

There is no steel products in the world that are completely rust free, and the principle of galvanized products (including zinc-iron alloy products) is a sacrificial anode protection law, that is, sacrifice the coating to protect the integrity of the steel base, which is a method to extend the service life of the steel base, and does not mean that the product is completely rust free. Therefore, even zinc-iron alloy products are necessary to be sprayed on the surface after production, and at present, the most typical anti-rust treatment of zinc-iron alloy products is passivation and oiling.
1. Passivation: The passivation process is a chemical reaction between the metal and the medium to generate an extremely thin protective film, which is usually composed of oxidizing agents and metal compounds, which can inhibit the anode reaction, so as to protect the zinc layer and achieve the effect of permanent rust.
2. Oiling: Surface oiling is the most concise and effective rust prevention method for steel products at present, and plays an irreplaceable lubrication role in the subsequent transportation or stamping process.