Zinc-10% Aluminum-Mischmetal Alloy Coated Steel Strand

Zn-10%Al · Ultra-High Corrosion Resistance · For Cables, Bridges, Slope Protection and Power Applications

Figure: Zinc-10% aluminum alloy coated steel strand wound on cable reels in a modern cable manufacturing workshop

Product Overview

Zinc-10% Aluminum-Mischmetal Alloy Coated Steel Strand (Zn-10%Al), also known as Super Galfan steel strand, is manufactured by helically stranding multiple high-carbon Steel Wires. Each individual steel wire is hot-dip coated with a zinc-10% aluminum-mischmetal alloy.

With the aluminum content increased to approximately 10%, the coating provides significantly improved corrosion resistance compared with conventional zinc-5% aluminum (Galfan) coatings. Depending on coating specifications and environmental conditions, Zn-10%Al coated steel strand can provide substantially longer corrosion protection and is an effective solution for outdoor applications exposed to severe corrosive environments.

Applicable Standards

National Standards (GB)

1. GB/T 20492-2019 — Zinc-5% Aluminum-Mischmetal Alloy Coated Steel Wire and Steel Strand
   Basic national standard for zinc-aluminum alloy coated steel wire and steel strand, with relevant requirements applicable according to product composition and application.

2. GB/T 32963-2026 — Zinc-Aluminum Alloy Coated Steel Wire Ropes
   New national standard for zinc-aluminum alloy coated steel wire ropes, scheduled to take effect in October 2026 and covering Zn-10%Al and ZnAlMg coatings.

3. GB/T 17101-2026 — Hot-Dip Galvanized or Zinc-Based Alloy Steel Wire for Bridge Cables
   Standard covering galvanized and zinc-based alloy steel wire for bridge cable applications, including applicable zinc-based alloy coatings. Scheduled to take effect in October 2026.

4. GB/T 45970-2025 — Steel Wire and Steel Wire Products: Zinc or Zinc-Aluminum Alloy Coatings
   General standard for zinc and zinc-aluminum alloy coatings on steel wire and steel wire products, effective from February 2026.

5. GB/T 1179-2017 — Round Wire Concentric-Lay Overhead Electrical Conductors
   Standard related to round-wire concentric-lay overhead electrical conductors and relevant stranded wire applications.

Ferrous Metallurgy Industry Standards (YB)

6. YB/T 6287-2024 — Low-Carbon Steel Wire with Hot-Dip Zinc-10% Aluminum Alloy Coating
   Specialized industry standard for low-carbon steel wire with a Zn-10%Al hot-dip alloy coating, effective from May 2025.

7. YB/T 183-2017 — Rare Earth Zinc-Aluminum Alloy Coated Steel Strand
   Industry standard for rare earth zinc-aluminum alloy coated steel strand.

8. YB/T 4574-2016 — Zinc-Aluminum Alloy Coated Steel Wire and Steel Strand for Prestressed Concrete
   Standard for zinc-aluminum alloy coated steel wire and steel strand used in prestressed concrete applications.

9. YB/T 124-2017 — Aluminum-Clad Steel Strand
   Standard for aluminum-clad steel strand used in cable and electrical applications.

Industry-Specific Standards

10. DL/T 700-2020 — Steel Strand for Ground Wires of Overhead Transmission Lines
    Electric power industry standard for steel strand used as overhead ground wire.

11. YD/T 1174-2008 — Galvanized Steel Strand for Aerial Communication Messenger Wires
    Telecommunication industry standard for galvanized steel strand used in aerial communication messenger wire systems.

12. TB/T 3449-2016 — Copper Alloy Stranded Wire for Railway Overhead Contact Systems
    Railway industry reference standard for stranded wires used in electrified railway overhead contact systems.

13. IEC 61089:2014 — Round Wire Concentric Lay Overhead Electrical Conductors
    International standard for round-wire concentric-lay overhead electrical conductors.

14. ASTM B802 / ASTM B803
    ASTM standards relating to zinc-coated and zinc-aluminum alloy coated steel wire and strand products, subject to the specific product and application requirements.

Figure: Close-up of zinc-10% aluminum alloy coated steel strand showing a uniform and continuous coating

Product Structure

The most common construction is 1×7, consisting of seven helically stranded steel wires. Other constructions, including 1×3, 1×19, and 1×37, are also available for specific applications.

Typical Specifications

• Common nominal diameters: 6 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 12.7 mm, and 15.2 mm

• Tensile strength grades: 1170, 1270, 1370, 1470, 1570, 1770, and 1860 MPa

• Coating mass: ≥250 g/m² for Class A specifications; ≥300 g/m² for heavy-duty coating specifications

• Aluminum content: 9%–11%, with a nominal aluminum content of approximately 10%, together with mischmetal elements

Key Performance Features

1. Excellent Corrosion Resistance

The zinc coating provides sacrificial cathodic protection to the steel substrate, while the aluminum forms a dense protective oxide film that helps slow corrosion.

Compared with conventional Hot-Dip Galvanized Steel strand, Zn-10%Al coated steel strand can provide substantially improved corrosion resistance and is particularly suitable for marine, salt-spray, industrial, and high-humidity outdoor environments.

2. Strong Coating Adhesion

The addition of mischmetal improves coating characteristics and contributes to a more uniform coating structure. The coating is designed to remain firmly bonded during bending and stranding, providing good resistance to coating damage during installation and tensioning.

3. Stable Mechanical Properties

The product retains the high-strength characteristics of the steel substrate, providing high breaking force and reliable long-term tensile performance for structural applications subject to sustained loads.

4. Uniform Coating

The Zn-10%Al coating is designed to provide consistent coverage and coating thickness, helping reduce the risk of bare spots and localized corrosion.

5. Lifecycle Cost Efficiency

Although Zn-10%Al coated steel strand generally has a higher initial purchase price than conventional galvanized or Zn-5%Al products, its enhanced corrosion resistance can reduce replacement frequency, maintenance requirements, and long-term operating costs in severe environments.

Technical Comparison of Three Coating Technologies

*Salt spray results and outdoor service-life figures are reference values only. Actual performance depends on coating mass, coating composition, test method, substrate condition, installation, environmental exposure, mechanical loading, and maintenance conditions. Project-specific standards and test reports should be used for formal acceptance.

Figure: Close-up of the stranded construction of zinc-aluminum alloy coated steel strand

Main Applications

1. Slope Protection and Rockfall Protection

Used in active and Passive Rockfall Protection Nets, slope anchors, rock slope stabilization systems, and geotechnical slope protection. Zn-10%Al coated steel strand is particularly suitable for projects exposed to moisture, salt spray, and aggressive outdoor environments.

2. Power and Telecommunication Infrastructure

Used for overhead ground wires, tower guy wires, communication messenger wires, and electrified railway overhead suspension applications, according to the relevant project requirements.

3. Cable Reinforcement

Used as reinforcement components in OPGW (Optical Ground Wire), submarine optical cables, and self-supporting optical cable systems, where high tensile strength and enhanced corrosion resistance are required.

4. Geotechnical Engineering

Used for ground anchors, rock bolts, excavation support, anchor cables, and prestressed engineering structures.

5. Bridge Cables

Used in cable-related applications for suspension bridge main cables, stay cables, and hanger cables, subject to the applicable bridge cable standards and engineering specifications.

6. Water Conservancy and Marine Engineering

Suitable for applications involving dams, embankments, coastal infrastructure, marine facilities, mooring systems, and offshore platform anchoring or stabilization where enhanced corrosion resistance is required.

7. Flexible Photovoltaic Structures

Used in tension cables and structural guying systems for flexible photovoltaic mounting structures and solar power installations.

Applications in Cable and Optical Cable Systems

Zinc-10% aluminum alloy coated steel strand can be used in various cable-related applications, including:

OPGW — Optical Ground Wire

Used as the mechanical and grounding component of Optical Ground Wire, which combines overhead grounding with optical fiber communication. A corrosion-resistant Zn-10%Al coating can improve protection of the steel components in exposed environments.

Aluminum-Clad Steel Strand — JLB / LBGJ

Aluminum-clad steel strand uses an aluminum layer over the steel core and is designed for applications requiring both mechanical strength and electrical conductivity.

Submarine Optical Cable Reinforcement

Used as a high-corrosion-resistance load-bearing or reinforcement component in certain submarine optical cable constructions.

ADSS — All-Dielectric Self-Supporting Optical Cable

Used in supporting or associated hardware systems for ADSS installations where applicable. The specific cable construction should be selected according to the cable manufacturer's design.

Cable Armor

Zinc-aluminum alloy coated steel wire or strand may be used as an armor or mechanical protection component in selected special-purpose cable constructions.

Purchasing Considerations

1. Clearly Specify the Applicable Standard

The purchasing specification should clearly identify the applicable standard, such as YB/T 6287-2024 or GB/T 32963-2026, where applicable.

The coating should be explicitly specified as:

“Zinc-10% aluminum-mischmetal alloy coating (Zn-10%Al)”

This helps prevent substitution with conventional galvanized or Zn-5%Al coated products.

2. Specify the Complete Product Configuration

The order should clearly state:

• Strand construction

• Nominal diameter

• Tensile strength grade

• Coating type

• Coating mass

• Aluminum content

• Lay direction

• Required dimensional tolerances

• Applicable testing and inspection requirements

3. Request a Coating Composition Test Report

For Zn-10%Al products, request a coating chemical composition test report to verify that the aluminum content meets the specified range.

Where the project specification requires 9%–11% aluminum content, the supplied product should be tested and documented accordingly.

4. Salt Spray Testing

For critical infrastructure projects, purchasers may request an independent or third-party salt spray test report to evaluate the corrosion resistance of the coating according to the specified test method.

5. Slope Protection Applications

In slope protection and rockfall protection systems, Zn-10%Al alloy coated steel strand is commonly used together with galvanized or zinc-aluminum-mischmetal coated steel wire, clips, anchors, and related slope stabilization components.

Why Choose Zn-10%Al Coated Steel Strand?

Zn-10%Al-mischmetal alloy coated steel strand is designed for applications where high tensile strength and long-term corrosion protection are both important.

Compared with conventional galvanized steel strand, its zinc-aluminum alloy coating can provide enhanced resistance to atmospheric corrosion, salt spray, moisture, and industrial exposure. It is therefore well suited to coastal infrastructure, power transmission, telecommunications, bridge cables, slope stabilization, marine engineering, and other demanding outdoor applications.

For each project, the final product selection should be based on the required mechanical properties, coating specification, environmental exposure, applicable standards, design life, installation conditions, and project-specific testing requirements.