In the modern industrial system, there is a material that has always played the role of an "invisible guardian". With steel as its core and a zinc coating as its armor, it supports the development of numerous industries such as construction, automotive, and home appliances through its excellent anti-corrosion performance and adaptability to multiple scenarios. This material is the galvanized coil. From the steel structural roofs of skyscrapers to the battery case enclosures of new energy vehicles, from the inner liners of household refrigerators to the anti-corrosion components of ocean-going ships, galvanized coils are ubiquitous, serving as an important benchmark for measuring the level of industrial manufacturing.
The core value of galvanized coils stems from their unique coating process. After decades of development, this process has evolved from simple anti-corrosion treatment to a precision-controlled manufacturing technology. Currently, the mainstream production process is dominated by continuous hot-dip galvanizing. In this process, cold-rolled or hot-rolled steel strips are degreased, annealed, and then immersed in molten zinc at 450°C. This forms a zinc protective film with a thickness of 60-275g/m² on the surface of the steel strips. During this process, a diffusion reaction occurs between zinc and iron at the interface, generating a zinc-iron alloy layer. This significantly enhances coating adhesion and ensures that the coating does not easily peel off during subsequent processing.
As manufacturing demands have advanced, technological innovations have continuously pushed the boundaries. In the field of ultra-thin specifications, a steel mill in Tangshan, Hebei Province has optimized welding parameters (15.5kA current, 3mm overlap) and coiling processes. This has controlled the thickness error of galvanized sheets within ±0.02mm, meeting the lightweight requirements of home appliances. In terms of surface refinement, the small zinc spangle process suppresses the growth of zinc grains through forced cooling, creating a uniform, spot-free coating. This solves the problem of slip lines in traditional materials during stamping forming. More notably, in the iteration of environmentally friendly processes, Baoshan Iron & Steel Co., Ltd. has developed a "chromium-free passivation + water-based coating" process, reducing VOCs emissions by 90%. Meanwhile, HBIS Group's zinc-aluminum-magnesium alloy coating technology has improved corrosion resistance by 3-5 times, perfectly aligning with the "dual carbon" strategy.
The integration of intelligent manufacturing has also brought about a qualitative leap in production efficiency. Ansteel Group has built the world's first "5G + AI" galvanized production line. By using machine vision to real-time detect zinc coating thickness, the product qualification rate has reached 99.8%, reducing the error rate of traditional manual inspection by over 80%. These technological innovations have not only improved product quality but also transformed galvanized coils from basic industrial materials into core components for high-end manufacturing.
The core competitiveness of galvanized coils lies in their "sacrificial anode" anti-corrosion mechanism. When the material is in a humid or corrosive environment, the zinc coating oxidizes first to form a dense oxide film. Like putting "protective armor" on steel, this prevents oxygen and moisture from contacting the base material. Experimental data shows that a galvanized sheet with a 600g/m² thick zinc coating can withstand over 2000 hours of salt spray testing without red rust. This is equivalent to a service life of 30 years in outdoor environments, making it the material of choice for marine climate zones and chemical industries.
Products from different brands exhibit distinct differences in performance. Baosteel's galvanized coils, with their thicker zinc coatings and high-quality base materials, excel in corrosion resistance and coating uniformity, making them suitable for harsh environments such as coastal areas and chemical plants. Ansteel's products stand out for their excellent ductility, making them ideal for the production of complex formed parts. Shaoguan Iron & Steel, on the other hand, excels in strength indicators, making its products more suitable for construction scenarios with high load-bearing requirements. This performance differentiation allows downstream enterprises to select products precisely based on specific needs, achieving a balance between performance and cost.
In terms of processing adaptability, galvanized coils also perform exceptionally well. After alloying treatment, the bonding strength between the zinc coating and the base material can be increased to 35MPa, with no peeling during 180° bending tests. Haier refrigerators use deep-drawing grade DX53D+Z material to manufacture inner liners, achieving a one-time forming qualification rate of 99.2%. This is a 12-percentage-point improvement compared to ordinary cold-rolled sheets, fully demonstrating its excellent processing performance. Additionally, the good electrical conductivity of the zinc coating (resistivity ≤0.15μΩ·m) eliminates the need for additional anti-corrosion treatment in scenarios such as communication base stations and power towers, further expanding its application scope.
As a highly versatile industrial material, the application scenarios of galvanized coils are continuously expanding from traditional fields to emerging markets. In 2023, the market size of China's hot-dip galvanized coil industry reached approximately 19.8 million tons, with sales revenue exceeding 520 billion yuan. It is expected that the market size will approach 580 billion yuan by 2025. Its growth momentum is closely tied to the upgrading of downstream industries.
In the construction sector, galvanized coils account for over 60% of the market share in steel-structured buildings. Beijing Daxing International Airport used Z275 galvanized sheets to manufacture its roofing system. By optimizing the zinc spangle structure (zinc grain diameter ≤0.2mm), it reduced light pollution while increasing wind pressure resistance to 2.5kPa. In prefabricated buildings, ultra-thin galvanized sheets with a thickness of 0.8mm are connected modularly through laser welding, improving construction efficiency by 40%. With the advancement of new urbanization, the central and western markets are becoming new growth poles for galvanized coil consumption, driven by projects such as the "Eastern Data and Western Computing" initiative.
The lightweight transformation of the automotive industry has created new opportunities for galvanized coils. The demand for high-strength, corrosion-resistant materials in new energy vehicles has surged. An automaker used Q355B+Z material to manufacture battery case enclosures. While maintaining a yield strength of 1200MPa, it extended the anti-corrosion service life to 15 years. In the body structure of the Tesla Model Y, the proportion of galvanized sheets has reached 38%, a 10-percentage-point increase compared to traditional models. This upgraded demand has driven leading steel enterprises to increase R&D investment in high-strength, high-corrosion-resistant products. The market share of high-end galvanized sheets from enterprises such as Baowu Group and HBIS Group in the automotive sheet market continues to rise.
The home appliance industry remains a stable consumer market for galvanized coils. In 2024, air conditioning production increased by 9.4% year-on-year, directly driving a surge in demand for galvanized sheets. Gree Electric's outdoor air conditioning unit casings use materials with a 600g/m² thick zinc coating, achieving "zero rust" operation in the high-temperature and high-humidity environment of Hainan. The SECE-grade galvanized sheets used in Haier refrigerator inner liners, after phosphating treatment, have extended the salt spray test cycle from 480 hours to 720 hours, fully meeting the durability requirements of home appliance products.
Currently, China's galvanized coil market is in a critical stage of structural optimization, with production capacity showing a clear trend of concentration. Against the backdrop of stricter environmental policies and dual control of energy consumption, small and medium-sized private galvanizing plants have been acceleratedly integrated or withdrawn from the market. The industry's CR10 (concentration ratio of the top 10 enterprises) has increased from approximately 46% in 2020 to 52% in 2023, and is expected to further rise to 58% by 2025. North China, East China, and South China remain the core consumption regions. Among them, East China, leveraging the advantages of the Yangtze River Delta manufacturing cluster, accounts for over 38% of the national total consumption.
The price formation mechanism shows regional differentiation. The East China market, relying on the advantages of industrial clusters, dominates the formation of price indices. However, due to differences in transportation costs and supply-demand imbalances, price differences between the northern and southern markets fluctuate frequently. In terms of cost-effectiveness, leading brands such as Baosteel have higher prices but offer greater overall value due to their long-term durability. Ansteel and Shaoguan Iron & Steel have moderate prices, suitable for most daily needs. Local brands have lower prices but have shortcomings in coating uniformity and corrosion resistance, requiring cautious selection.
In the future, the galvanized coil industry will achieve high-quality development driven by both green low-carbon development and intelligent manufacturing. Guided by the "dual carbon" goals, the energy consumption standard for electro-galvanizing production lines will be reduced from 180kgce/t to 150kgce/t by 2025. The temperature control accuracy of hot-dip galvanizing zinc pots will be improved to ±2°C. The gradual integration of carbon trading mechanisms will further compel enterprises to reduce emission intensity. At the technical level, processes such as zinc-aluminum-magnesium alloy coatings and chromium-free passivation will be accelerated, further enhancing product performance and environmental attributes.
The expansion of application scenarios is also promising. In the energy storage field, container casings made of galvanized sheets have passed the A60 fire resistance test, becoming a standard configuration for electrochemical energy storage systems. In the hydrogen energy industry, galvanized sheet pipeline systems have passed the -40°C low-temperature impact test, meeting the requirements of liquid hydrogen transportation. At the same time, the infrastructure construction needs of countries participating in the "Belt and Road" Initiative provide new space for galvanized coil exports, although enterprises need to remain vigilant against policy risks such as anti-dumping investigations.
From steel base materials to anti-corrosion tools, from traditional manufacturing to high-end empowerment, the development of galvanized coils reflects the trajectory of the upgrading of China's industrial materials. Amid the wave of green economy and intelligent manufacturing, this "steel guardian" with both performance advantages and adaptability will continue to support the steady development of modern industry and write more chapters of industrial innovation.
