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HaiGang Yunyi
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Tianjin Haigang Steel Coil
Service first, quality assured. More dedicated and focused on crafting even better boards.
22
2021
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03
Galvanized Strip Steel Improves Galvanizing Pre-treatment (Part 2)
I. Platability of Duplex Steel
For high-strength steels in the silicon-manganese alloy series, when the strip steel is heated in the furnace, the alloying elements—silicon and manganese—tend to precipitate internally. These closely spaced silicon-manganese precipitates can subsequently bond together into flaky structures. This alloy precipitate layer, which covers the surface of the strip steel, significantly impairs its platability. When the strip steel enters the zinc bath for hot-dip galvanizing, the molten zinc cannot effectively wet this particular area, thereby reducing the adhesion of the zinc coating in that region. Moreover, larger areas of precipitate exceed the surface tension of the molten zinc, preventing the zinc from adhering and covering the surface properly, resulting in defects such as missing coatings on the strip steel. The extent of these defects is directly proportional to the amount of silicon-manganese alloy added—in other words, the higher the silicon-manganese content, the larger the area affected by missing coatings. To mitigate the adverse effects of silicon-manganese alloys on the wettability of the strip steel and improve the platability of the steel sheet, the primary measures currently being adopted include controlling the composition of the raw alloy materials and implementing a pre-oxidation process.
II. Control of Alloy Composition
To enhance the platability of steel plates and reduce the impact of silicon-manganese alloy precipitation, the alloy composition is controlled at the raw material stage by keeping the addition amount of the silicon-manganese alloy within a certain range. Additionally, by adding alloys such as chromium and molybdenum to improve performance, the platability of the steel plate can be effectively increased.
III. Atmosphere Control
By independently controlling the atmospheric conditions in different temperature zones within the furnace, the alloy layers on the surface of the strip steel are pre-oxidized and sealed, preventing them from precipitating out. The strip steel then passes through a homogenization section with a specific hydrogen concentration, where the oxide layer is reduced. As a result, the alloy layers inside the strip steel remain in their original state, and the wettability of the strip steel is not adversely affected.
Galvanized, strip steel, oxidation
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We primarily produce various products including galvanized strip steel, pickled strip steel, and cold-rolled strip steel. These products are widely used in industries such as construction, mechanical manufacturing, automotive, and household appliances.
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Shuangtang High-end Hardware Products Industrial Park, Jinghai District, Tianjin City
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