Zinc Coating: Coating Thickness 5-25 μm per side

Component Specifications

Definition

Zinc coating, specifically in galvanized steel coil production, refers to the metallurgical bonding of zinc to steel substrate through hot-dip galvanizing process. This involves immersing cleaned steel coils in molten zinc bath at approximately 450°C, forming a series of zinc-iron alloy layers that provide sacrificial cathodic protection against corrosion. The coating thickness typically ranges from 5-25 μm per side, with zinc content exceeding 99% purity.

Working Principle

The working principle relies on electrochemical protection where zinc acts as a sacrificial anode. When the coated steel is exposed to corrosive environments, zinc preferentially corrodes to protect the underlying steel substrate. The zinc-iron intermetallic layers (Gamma, Delta, Zeta) formed during galvanizing create a barrier that slows down corrosion progression while maintaining adhesion to the steel surface.

Materials

High-purity zinc (99.995% Zn minimum) with controlled additions of aluminum (typically 0.15-0.25% Al) to improve coating adhesion and appearance. The steel substrate is typically low-carbon steel with controlled silicon and phosphorus content to ensure proper zinc-iron alloy formation.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Adhesion	No flaking after 180° bend test
Zinc Purity	≥99.995%
Coating Class	G60 to G275 (ASTM A653)
Coating Weight	60-275 g/m²
Surface Finish	Regular spangle, minimized spangle, or smooth finish
Coating Thickness	5-25 μm per side

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 1461, ASTM A653, EN 10346, JIS G3302

Parent Products

This component is used in the following industrial products

Galvanized Steel Coil

Galvanized steel coil is a semi-finished industrial material consisting of steel sheet coated with a protective zinc layer through hot-dip galvanization.

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Pre-Painted Galvanized Steel Coil

Factory-coated steel coil with corrosion protection and decorative finish for metal furniture manufacturing.

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Engineering Analysis

Risks & Mitigation

Zinc whisker formation in data centers
White rust formation during storage
Reduced coating adhesion on high-silicon steels
Hydrogen embrittlement risk

FMEA Triads

Trigger: Inadequate surface cleaning before galvanizing
Failure: Poor coating adhesion and bare spots
Mitigation: Implement multi-stage cleaning (alkaline degreasing, acid pickling, fluxing) with automated quality control

Trigger: Excessive aluminum in zinc bath
Failure: Brittle coating with cracking during forming
Mitigation: Maintain aluminum content at 0.15-0.25% with continuous bath analysis

Trigger: Improper cooling rate after galvanizing
Failure: Excessive spangle size affecting paint adhesion
Mitigation: Implement controlled air knife systems and water quenching for consistent cooling

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Coating weight tolerance: ±10% of nominal value, Thickness uniformity: ±1.5 μm across coil width

Test Method

Coating weight measured by X-ray fluorescence (ASTM A754), adhesion tested by bend test (ASTM D522), corrosion resistance by salt spray test (ASTM B117)

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of Zinc Coating

Manufacturer profiles associated with Zinc Coating.

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Related Components

Work Rolls

Work rolls are precision cylindrical components in heavy-duty rolling mills that directly contact and deform metal during rolling operations.

Venting Channels

Venting channels are precision-engineered passages in metal casting mold cores designed to allow gases to escape during the molten metal pouring process, preventing defects and ensuring high-quality castings.

Aluminum Matrix

Aluminum matrix is the continuous metallic phase in aluminum matrix composites, providing structural integrity and thermal/electrical conductivity in hot-forged aluminum alloy billets.

Grain Structure

The crystalline arrangement of atoms in hot-forged aluminum alloy billets, determining mechanical properties and performance.

Frequently Asked Questions

What is the difference between regular and minimized spangle zinc coating?

Regular spangle shows visible zinc crystals with metallic luster, while minimized spangle has smaller, less visible crystals achieved through controlled cooling, providing better paint adhesion and uniform appearance.

How long does zinc coating protect steel from corrosion?

Protection duration depends on coating thickness and environment. In moderate industrial atmospheres, 20 μm coating typically provides 15-25 years of protection before maintenance painting is needed.

Can zinc-coated steel be welded?

Yes, but requires proper techniques. Zinc vaporization during welding can cause porosity, so increased ventilation and specific welding parameters (lower heat input) are recommended.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Zinc Coating