Corrosion Resistance Champion + Strength Leader: Aluminum-Zinc Coated Steel Strand Becomes the First Choice for Harsh Environment Projects
With the smooth opening of major projects such as the Guangdong Humen Second Bridge and the China-DPRK Yalu River Boundary Bridge, as well as the intensive launch of offshore wind power projects, a core material with super corrosion resistance and high mechanical strength—aluminum-zinc coated steel strand—has become a "hot commodity" in engineering construction. This special steel strand, coated with a zinc-5% aluminum-mixed rare earth alloy layer on its surface, boasts durability far exceeding that of traditional galvanized products. It performs exceptionally well in harsh environments such as coastal salt spray, industrial corrosion, and deep seas, serving as a core support for ensuring long-term engineering safety in fields including power, bridges, and new energy.
Core Features: Dual Breakthroughs in Corrosion Resistance and Strength
The core competitiveness of aluminum-zinc coated steel strand stems from its innovative coating technology and structural design. Unlike traditional galvanized steel strands, its coating is composed of zinc, aluminum, and rare earth elements, with an aluminum content of no less than 4.2%. Through the hot-dip coating process, a dense alloy protective layer is formed, combining the chemical stability of aluminum with the electrochemical protection characteristics of zinc. Its corrosion resistance is 3-5 times higher than that of traditional galvanized products, and its service life can be extended to over 30 years in coastal salt spray environments—far exceeding the 8-12 year service life of ordinary galvanized steel strands.
In terms of mechanical properties, the product also delivers outstanding performance. Its base material is low-carbon steel with a carbon content of ≤0.25%, manufactured through multiple cold drawing and precision stranding processes. The tensile strength can reach 1670-2000MPa, and the breaking force meets the load requirements of various projects. For example, the GJ-50 model has a breaking force exceeding 50kN, fully suitable for heavy-load scenarios such as bridge stay cables and power transmission towers. Meanwhile, the coating forms a strong metallurgical bond with the base material, featuring high adhesion that prevents peeling during construction bending and tensioning, effectively avoiding local corrosion caused by coating damage.
Standardized production and strict quality control further consolidate the quality line. The product must comply with the national standard GB/T 20492-2019, with clear requirements for coating thickness, mechanical properties, corrosion resistance, and other indicators. Leading enterprises adopt technologies such as intelligent temperature-controlled coating and online coating detection to ensure the product qualification rate remains stable above 99.5%, providing reliable guarantees for engineering safety.
Application Scenarios: Breaking Through in Multiple Fields Under Harsh Environments
The application scenarios of aluminum-zinc coated steel strand have fully expanded from traditional infrastructure to high-demand, high-difficulty projects, especially demonstrating irreplaceable value in harsh environments. In the field of bridge engineering, it has become the preferred material for stay cables of long-span bridges—the Humen Second Bridge's Nizhou Waterway Bridge uses approximately 16,000 tons of the product, and the Wuhan Yangsigang Yangtze River Bridge uses up to 20,000 tons. Its super corrosion resistance and high tensile strength ensure the safety of bridges serving for a century in outdoor environments; the 3,026-meter-long China-DPRK Yalu River Boundary Bridge adopts the product for all 152 stay cables, successfully withstanding the corrosive environment of the cross-border river.
The power transmission sector is another major battlefield. In State Grid's UHV projects and the "West-to-East Power Transmission" program, aluminum-zinc coated steel strands are used as overhead ground wires and conductor reinforcement cores, adapting to 110kV-500kV voltage levels and operating stably in complex environments such as the northwest Gobi and southwest humid and hot regions, reducing line operation and maintenance frequency and replacement costs. In 2025, the domestic power industry's demand for the product accounted for 68%, making it one of the core materials for power grid upgrading and transformation.
Demand in the new energy and marine engineering sectors is growing rapidly. In offshore wind power projects, its salt spray resistance and wave erosion resistance make it a core material for tower fixing and cable laying, currently applied in multiple offshore wind farms in the Yangtze River Delta and Pearl River Delta; in the photovoltaic bracket field, the product's long service life advantage has driven its market share to grow rapidly from 5.7% in 2025, adapting to the long-term outdoor service needs of photovoltaic power stations in deserts, coastal areas, and other regions. In addition, aluminum-zinc coated steel strand has also been widely used in high-corrosion-risk scenarios such as chemical parks, ports and terminals, and highway guardrails, effectively reducing the full-life-cycle cost of projects.
Industry Trends: Growth Driven by Dual Engines of Policy and Demand
In recent years, China's aluminum-zinc coated steel strand industry has entered a period of rapid development. Market data shows that the domestic market size reached 7.83 billion yuan in 2024, and is expected to increase to 8.5 billion yuan in 2025, a year-on-year growth of 12.3%. The compound annual growth rate is expected to remain around 9.7% over the next five years, potentially exceeding 13.5 billion yuan by 2030. This growth is mainly driven by the dual engines of policy support and downstream demand—continuous release of policy dividends such as the 2.8 trillion yuan investment in the "14th Five-Year Plan" power grid layout and accelerated development of offshore wind power has provided broad market space for the industry.
Technological upgrading and industrial integration have become key words for industry development. Currently, new technologies such as zinc-aluminum-magnesium alloy coating and chromium-free passivation are accelerating industrialization, further improving product corrosion resistance and environmental protection levels; industry concentration is constantly increasing, with the top five enterprises accounting for 45% of the market share, expected to rise to 58% by 2028. Small and medium-sized enterprises are gradually withdrawing from the market due to environmental and cost pressures. Meanwhile, the export market has performed brilliantly, with exports reaching 26,000 tons in 2024. Countries along the "Belt and Road" have become major growth points, and the Southeast Asian market share is expected to rise to 53% by 2030. Domestic products are gradually opening up the international market with their cost-effectiveness and technological advantages.
Industry experts stated that as engineering construction transitions towards "high standards and long service life", aluminum-zinc coated steel strands will develop towards higher strength, better corrosion resistance, and intelligent monitoring. For example, products embedded with IoT chips to achieve full-life-cycle traceability are expected to account for over 30% of the market share by 2030. In the future, driven by the construction of a new power system and the Transportation Power strategy, the product will continue to benefit from demand growth in power, bridges, new energy and other fields, providing solid support for China's high-quality infrastructure development.