Knowledge of hot-dip galvanized steel sheet

one、definition

Hot dip galvanized steel sheet refers to the process of hot-dip galvanizing，Steel with a zinc protective layer formed on the surface of the steel plate。This process not only improves the corrosion resistance of steel plates，It also extended its service life。Hot dip galvanized steel sheet is widely used in construction、automobile making、Multiple fields such as home appliances。

two、Production process

The production of hot-dip galvanized steel sheet mainly adopts continuous hot-dip galvanizing process，The core steps are as follows：

Uncoiling and welding：After unwinding the steel coil，Weld the tail of the forward strip steel to the head of the backward strip steel，Ensure continuous production of the unit。

Degreasing cleaning：By spraying、scrub、Electrolytic cleaning and other methods to remove grease and iron powder from the surface of the strip steel，Ensure coating adhesion and surface quality。

annealing：Recrystallize and anneal the strip steel，To achieve good mechanical performance，And optimize the coating performance by controlling the furnace atmosphere。

CGL：Immerse the pre treated strip steel into a temperature of450℃ - 470℃Galvanizing in molten zinc solution。

Air knife controls the thickness of the zinc layer：Spray gas onto the surface of the strip steel through an air knife（Like air or nitrogen），Control the thickness of the zinc layer。

Cooling and passivation treatment：Galvanized strip steel after cooling，Usually, passivation treatment is carried out in chromic acid or phosphoric acid solution，F(xiàn)orming a protective film，Improve anti-corrosion performance。

Correction and Inspection：Correct the galvanized strip steel，Restore its flatness，And conduct quality inspection。

three、Performance characteristics

corrosion resistance：The zinc layer can effectively isolate the steel plate from the external environment，prevent corrosion，Its corrosion resistance is usually the same as that of ordinary steel25times。

Strong adhesion：The zinc layer is firmly bonded to the steel plate，Not easy to fall off。

Good processing performance：Has good formability and weldability，Suitable for various processing techniques。

anodic sacrifice protection：Zinc is more prone to oxidation than iron，Even if scratches appear on the surface of the coating，Zinc will also preferentially corrode，Thus protecting the substrate。

four、application area

construction industry：Used for roofs、wall、Structural components such as drainage ditches，Provide long-term rust prevention protection。

Automobile industry：Used for vehicle body components、Chassis, etc，Enhance the durability and safety of vehicles。

Home appliance manufacturing：Used for refrigerators、washing machine、Air conditioning and other enclosures，Enhance aesthetics and durability。

five、Common problems and solutions

Zinc layer peeling off：Possible surface oxidation、Cold rolling emulsion is unclean、Caused by low aluminum content in zinc pots。

White rust and black spots：Usually due to the surface not being coated with oil、Due to residual moisture or improper storage，Attention should be paid to moisture prevention and timely handling。

Hot dip galvanized steel sheet due to its excellent corrosion resistance and processing performance，Plays an important role in modern industry。By optimizing production processes，It can further enhance its performance and application scope。