High Corrosion Resistance + Strong Adaptability: Technological Upgrades of Galvanized Steel Strands Empower Multi-Field Infrastructure
Driven by the continuous advancement of infrastructure projects such as UHV power grids, offshore wind power, and bridge engineering, galvanized steel strands have become core rigid-demand products in the high-end wire market due to their excellent anti-corrosion performance and mechanical strength. The domestic market scale of galvanized steel strands is expected to exceed 32 billion yuan in 2025, a year-on-year increase of 11.3% compared with last year. The iteration and upgrading of production processes and technological innovations are becoming the core driving forces for the high-quality development of the industry, promoting products to achieve breakthroughs in more harsh scenarios.
Core Features: Three Major Advantages Lay a Solid Foundation for Application
The core competitiveness of galvanized steel strands stems from the threefold characteristics of "anti-corrosion + strength + adaptability", making them irreplaceable in complex environments. Firstly, superior corrosion resistance is its iconic advantage. Through the sacrificial anode protection of the zinc coating, it can effectively isolate the contact between air, moisture and the steel base. Traditional hot-dip galvanized products can have a service life of 15-20 years in ordinary atmospheric environments, while the upgraded Zn-Al-Re alloy coated products have 3-5 times higher corrosion resistance, with no red rust time exceeding 1800 hours in neutral salt spray tests, suitable for extreme environments such as high salt fog in coastal areas and sandstorms in northwest China. Secondly, high mechanical strength is outstanding. The tensile strength of mainstream products ranges from 1570MPa to 1960MPa, and some special models can reach 2160MPa, while maintaining an elongation rate of ≥4.5%. They can withstand long-term dynamic loads and complex stresses, meeting the high-strength requirements of main cables for long-span bridges, anchoring of wind power towers, etc. Thirdly, wide scenario adaptability. Product specifications cover φ12.7mm-φ28.6mm, with structures including 1×7, 1×19 and other types. According to the needs of different fields such as power, transportation, and new energy, the zinc coating thickness (120g/m²-400g/m²) and strength grade can be customized to achieve "one material for multiple uses".
Production Process: Refined Control of Quality Throughout the Whole Process
The production of galvanized steel strands is a systematic project of "raw material purification - processing and forming - coating protection", and each process directly affects the final performance of the product.
Step 1: Raw Material Preparation and Wire Drawing. High-quality high-carbon steel wire rods (carbon content 0.65%-0.85%) are selected as the base material. First, strict surface cleaning is carried out, including pickling to remove scale, alkaline degreasing, water washing and neutralization, to ensure no residual impurities on the steel base surface. Then, it enters the wire drawing process. A continuous wire drawing machine is used to gradually reduce the diameter through multiple dies to draw the steel wire to the preset diameter. At the same time, temperature control treatment is used to improve the tensile strength and toughness of the steel wire. During the wire drawing process, graphite lubricant is used to reduce friction and avoid surface scratches.
Step 2: Stranding and Forming. Multiple drawn steel wires are sent to a stranding machine for stranding according to the preset lay length and lay direction (left lay or right lay) to form a steel strand blank. The lay length of mainstream 1×7 structure products is controlled at 12-16 times the diameter of the steel strand to ensure a compact structure and uniform force. For large-section or special structure products, pre-deformation technology is used to treat the steel wires, reducing the residual stress of the steel strand after stranding and improving overall stability.
Step 3: Galvanizing Treatment (Core Process). At present, the industry mainly adopts two types of processes: hot-dip galvanizing process and alloyed galvanizing process. In the hot-dip galvanizing process, the steel strand blank is preheated (temperature 450-500℃) and then immersed in molten zinc liquid at 445-460℃. The zinc liquid forms a metallurgical bonding layer with the steel base, and then the zinc coating thickness is controlled by air knife blowing. After cooling, a uniform and dense pure zinc coating is formed. The alloyed galvanizing process adds alloying treatment on the basis of hot-dip galvanizing. The galvanized steel strand is heated to 500-550℃ to make the zinc coating react with the steel base to form a Zn-Fe alloy layer, which further improves the coating adhesion and corrosion resistance, and is suitable for high-demand scenarios.
Step 4: Post-Treatment and Inspection. After galvanizing, the steel strand undergoes cooling and passivation treatment (some products use chromate or chromium-free passivation) to enhance the anti-discoloration ability of the zinc coating. Then, through the online inspection system, ultrasonic flaw detection is used to detect internal defects, eddy current testing to check the continuity of the zinc coating, and laser diameter gauge to control the outer diameter tolerance. At the same time, sampling is carried out for tensile test, bending test and salt spray test to ensure that the product meets the requirements of the new national standard GB/T 33363-2026, and unqualified products are directly rejected.
Technological Upgrades: Dual Breakthroughs in Greenization and Intelligence
The current galvanized steel strand industry is accelerating its transformation towards "high efficiency, low carbon and precision". In terms of green production, the penetration rate of cyanide-free galvanizing technology has reached 78%, replacing the traditional cyanide galvanizing process and reducing heavy metal pollution. Enterprises such as Hebei Iron and Steel Group and Baowu Group have introduced green power production, combined with waste heat recovery systems, reducing unit product energy consumption by 18% compared with 2020, and carbon emission intensity to below 0.8tCO₂/t, meeting the compliance requirements of the EU Carbon Border Adjustment Mechanism (CBAM). In terms of intelligent transformation, leading enterprises have adopted AI closed-loop control systems to real-time adjust parameters such as wire drawing speed, zinc liquid temperature and air knife pressure, controlling the zinc coating thickness tolerance within ±5μm, and increasing the product first-pass yield to 97.6%. The application of machine vision inspection technology realizes millisecond-level identification of surface defects, and the inspection efficiency is 10 times higher than that of manual work.
Market Application: Continuous Expansion of Demand in Multiple Fields
With stable performance and technological upgrades, the application boundaries of galvanized steel strands are constantly expanding. In the power sector, in the 2025 UHV project bidding of State Grid, the procurement volume of galvanized steel strands increased by 23% year-on-year, mainly used for ground wires of transmission lines and tower anchoring. In the transportation field, in bridge projects in coastal areas such as Guangxi and Fujian, the proportion of alloyed galvanized steel strands has exceeded 40%, solving the anti-corrosion problem in marine environments. In the new energy sector, offshore wind power projects have driven a surge in demand for high-corrosion-resistant galvanized steel strands, and the related demand growth rate is expected to reach 28% in 2025, becoming a new growth engine of the industry.
Industry experts said that in the future, galvanized steel strands will develop towards the direction of "higher strength, better corrosion resistance and lower energy consumption". The industrialization of new technologies such as Zn-Al-Mg alloy coatings and intelligent sensing coatings will further enhance product added value. Enterprises need to continue to focus on process optimization and green transformation to seize opportunities in the wave of high-quality infrastructure development.