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Hot-dip galvanizing (HDG) immerses cleaned and fluxed steel fasteners into molten zinc at 420–530 °C, forming a metallurgical bond. The resulting coating consists of zinc-iron alloy layers covered by an outer pure zinc layer.
Hot-dip galvanizing (HDG) immerses cleaned and fluxed steel fasteners into molten zinc at 420–530 °C, forming a metallurgical bond. The resulting coating consists of zinc-iron alloy layers covered by an outer pure zinc layer.
Process Principle
Hot-dip galvanizing (HDG) immerses cleaned and fluxed steel fasteners into molten zinc at 420–530 °C, forming a metallurgical bond. The resulting coating consists of zinc-iron alloy layers covered by an outer pure zinc layer.
Key Characteristics
Very thick coating – typical average thickness ≥ 43 μm, much thicker than electroplating.
Extremely long service life – 30–80 years in general atmospheric environments.
Dual protection – physical barrier plus sacrificial cathodic protection.
Dimensional change – thick coating alters thread dimensions; tolerances must be accounted for.
Applications
Outdoor heavy steel structures requiring long service life, e.g., power transmission towers, highway guardrails, bridges, building steelwork. However, the high temperature may cause temper embrittlement in high-strength fasteners (≥10.9 grade), so caution is needed.
Process Principle
Hot-dip galvanizing (HDG) immerses cleaned and fluxed steel fasteners into molten zinc at 420–530 °C, forming a metallurgical bond. The resulting coating consists of zinc-iron alloy layers covered by an outer pure zinc layer.
Key Characteristics
Very thick coating – typical average thickness ≥ 43 μm, much thicker than electroplating.
Extremely long service life – 30–80 years in general atmospheric environments.
Dual protection – physical barrier plus sacrificial cathodic protection.
Dimensional change – thick coating alters thread dimensions; tolerances must be accounted for.
Applications
Outdoor heavy steel structures requiring long service life, e.g., power transmission towers, highway guardrails, bridges, building steelwork. However, the high temperature may cause temper embrittlement in high-strength fasteners (≥10.9 grade), so caution is needed.