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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.
19
2021
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03
Galvanized Strip Steel—Improved Pretreatment for Enhanced Coatability (Part 1)
Acid wash
I. The Significance of Adding Pickling to the Hot-Dip Galvanizing Process Using the Reduction Method
To ensure that the zinc coating adheres firmly to the steel surface, no foreign substances must be trapped between the coating and the steel substrate. Therefore, in conventional hot-dip galvanizing processes, a pretreatment section must be incorporated prior to the dipping stage. The strip steel first passes through a degreasing section to thoroughly remove surface contaminants such as oils, iron powder, and dust. As for removing iron oxide scale, the main methods include acid pickling, hydrogen reduction, and a combination of acid pickling followed by hydrogen reduction.
The high-grade continuous hot-dip galvanizing line using the All-American Steel Alliance process, primarily used for producing automotive sheet metal, has added an acid pickling tank downstream of the electrochemical degreasing tank in the degreasing section. Its functions are as follows:
1. The removal of iron oxide scale from the strip steel surface is more thorough, which further enhances the adhesion of the zinc coating and enables hot-dip galvanized strip steel to withstand even more demanding subsequent processing.
2. Achieving a lower dew point temperature of the furnace atmosphere significantly reduces the likelihood of oxidation on the surface of the furnace rolls, thereby lowering the risk of scale formation on the furnace rolls and indirectly improving the surface quality of the steel strip.
3. For production lines that require externally purchased cold-rolled strip steel, since the procurement or transshipment of cold-rolled strip steel takes a relatively long time and is affected by environmental factors during transportation, the surface of the steel sheets may undergo a certain degree of oxidation. The pickling process in the degreasing section can effectively remove these oxides.
Preprocessing, strip steel, pickling, oxidation, hot-dip galvanizing, degreasing, surface treatment, reduction method, cleaning, steel plate
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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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tjhaigang@tjhaigang.com
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