Do you know that the thickness of galvanized sheet metal is like a mysterious "size chart" with different specifications! Generally speaking, its thickness "dances" in the range of 0.2mm to 3.0mm. Thin galvanized sheet metal, lightweight and flexible, suitable for places with high weight requirements; Thick ones are like strongmen, sturdy and durable, often used in scenes that require strong support. Galvanized sheet metals of different thicknesses play unique roles on their respective stages. This article will systematically analyze the key elements of galvanized sheet metal thickness from three dimensions: process standards, application scenarios, and technical specifications.

1. Process standard system for thickness of galvanized sheet metal

The thickness parameters of galvanized sheet metal include two dimensions: substrate thickness and galvanized layer thickness, which together constitute the protective system of the product. According to the International Organization for Standardization (ISO) and Chinese National Standards (GB/T), a complete system of thickness specifications for galvanized sheet metals has been formed.

1. Classification standard for substrate thickness

The thickness of the substrate is the core indicator of the load-bearing capacity of galvanized sheet metals. According to the GB/T 2518-2019 "Continuously Hot dip Galvanized sheet metal and Strip" standard, the mainstream product substrate thickness range in the market is 0.25mm-4.0mm, and the specific classification is as follows:
(1) Ultra thin type (0.25mm-0.5mm): mainly used for weight sensitive scenarios such as electronic component packaging and lightweight decorative components. The products in this thickness range require high-precision cold rolling technology to ensure that the flatness error of the plate shape is ≤ 0.5mm/m.
(2) Universal type (0.6mm-1.5mm): covering 80% of application areas such as building roofs, walls, ventilation ducts, etc. Among them, products with a thickness of 1.0mm occupy 65% of the construction market share due to their cost-effectiveness advantage.
(3) Thick plate type (1.6mm-4.0mm): Used in scenarios that require high-strength support, such as heavy machinery protective covers and bridge steel structures. This type of product requires quenching process to eliminate internal stress and prevent processing deformation.

2. Technical specifications for thickness of galvanized layer

The thickness of the galvanized layer directly determines the corrosion resistance life of the metal plate. According to GB/T 13912-2020 "Technical Requirements for Hot Dip Galvanized Coatings on Iron and Steel Parts with Metal Coating", the thickness of the galvanized layer is divided into two categories according to the process:
(1) Hot dip galvanized layer: An alloy layer is formed by immersing steel in a molten zinc solution at 450 ℃ -470 ℃. The weight of the single-sided galvanized layer must be ≥ 275g/m 2 (approximately 38 μ m). For high corrosion scenarios such as marine environments, the standard requires a single-sided galvanized layer weight of ≥ 500g/m 2 (approximately 70 μ m).
(2) Electroplated zinc layer: A zinc layer is deposited on the surface of steel using electrolytic technology, with a thickness typically controlled between 5 μ m-15 μ m. This process product is widely used in fields with strict appearance requirements, such as home appliance casings and interior decoration, due to its high surface smoothness.

3. Technical standards for thickness detection

Thickness control relies on precise detection methods. According to ASTM E376 standard, on-site testing mainly adopts two methods:
(1) Magnetic thickness gauge method: By utilizing the difference in magnetic permeability between the zinc layer and the substrate, the thickness of the galvanized layer can be quickly measured with an accuracy of ± 1 μ m. It should be noted that curvature correction is required during the inspection of curved components.
(2) Weighing method: Calculate the thickness by dissolving the galvanized layer and weighing it, with an accuracy of ± 0.5 μ m. Although this method takes a long time, it is widely used as an arbitration detection method for quality dispute resolution.

2. The application selection logic of galvanized sheet metal thickness

The selection of thickness requires comprehensive consideration of three major factors: environmental corrosiveness, structural load-bearing requirements, and economy, forming a scientific selection matrix.

1. Matching of environmental corrosiveness classification

According to the ISO 9223 standard, environmental corrosiveness is divided into five levels, C1 to C5, corresponding to different thickness requirements:
(1) C1 (indoor dry environment): Optional 0.5mm substrate+12 μ m galvanized layer, suitable for scenarios such as office partitions and indoor ceilings.
(2) C3 (urban industrial environment): 1.0mm substrate+65 μ m hot-dip galvanized layer is required. Typical applications include factory walls, ventilation ducts, etc.
(3) C5 (marine high salt environment): 2.0mm substrate+85 μ m hot-dip galvanized layer must be used, such as coastal power plant equipment protective covers, port crane structural components, etc.

2. Structural mechanical performance requirements

The thickness selection needs to meet the triple requirements of bearing capacity, stiffness, and stability:
(1) Wind resistance design: Galvanized sheet metal for building curtain walls needs to be calculated according to GB 50009-2012 "Code for Load of Building Structures". In areas with wind force of level 10, a 0.8mm substrate can meet the requirements, while in areas with wind force of level 12, a 1.2mm substrate is required.
(2) Seismic design: In the seismic intensity zone of 8 degrees, the thickness of galvanized sheet metal used for equipment foundation needs to be increased by 20% to prevent fatigue cracking caused by vibration.
(3) Fatigue life requirement: For components that can withstand alternating loads for a long time, such as galvanized sheet metals used for bridge supports, the thickness of the substrate should be increased by 30% compared to static load-bearing components.

3. Whole life cycle economic optimization

The thickness selection needs to balance the initial cost and maintenance cost:
(1) Cost model: Taking a 1000m 2 roof as an example, the initial cost of using a 0.6mm substrate and a 65 μ m galvanized layer is 120000 yuan, but the 15 year maintenance cost reaches 30000 yuan; The initial cost of using a 1.0mm substrate and a 85 μ m galvanized layer is 180000 yuan, and the maintenance cost is only 15000 yuan. By calculating the net present value, the latter is more economical over a 20-year period.
(2) Carbon footprint consideration: Although the thick plate scheme increases material consumption, due to reduced maintenance frequency, the full lifecycle carbon emissions can be reduced by 18%, which is in line with the trend of green building development.

3. The Technological Development Trend of Galvanized Sheet Metal Thickness

With the advancement of materials science and manufacturing technology, the thickness control of galvanized sheet metals is evolving towards precision and functionality.

1. Intelligent thickness control system

The new generation of hot-dip galvanizing production line adopts laser thickness gauge and closed-loop control system, which can achieve real-time adjustment of galvanized layer thickness with an error control within ± 2 μ m. The intelligent galvanizing line put into operation by Baosteel in 2024 has increased the consistency of product thickness by 40%.

2. Composite coating technology

By adding alloy elements such as Al and Mg to the galvanized layer, a Zn Al Mg composite coating is formed, which increases the corrosion resistance by three times while maintaining the same thickness. This technology has been applied to the protective plate of new energy vehicle battery packs, extending the product's lifespan from 8 years to 25 years.

3. Lightweight design innovation

Adopting a high-strength steel substrate combined with a thin galvanized layer scheme to reduce weight while ensuring performance. The DP780 high-strength galvanized sheet metal developed by Shougang Group can still meet the requirements of automotive safety components with a substrate thickness reduced to 0.8mm, which is 33% lighter than traditional 1.2mm products.
In summary, the thickness range of galvanized sheet metal is usually 0.2mm-3.0mm, and different thicknesses are suitable for various scenarios. Thin plates are active in weight sensitive fields due to their lightweight advantage; Thick plates, with their high strength, demonstrate their strength in areas that require strong support. With the development of technology, the thickness control of galvanized sheet metals will be more precise in the future, which can meet more complex needs. Its application fields will also continue to expand, bringing more innovative possibilities to architecture, industry, and other fields. We should keep up with the pace of technology, make reasonable use of galvanized sheet metals of different thicknesses, and promote various industries to reach new heights.