What is the difference between galvanized and galvanized steel?

In the modern fields of metal processing and construction manufacturing, galvanized materials have become an important choice for various industries due to their excellent corrosion resistance, high cost-effectiveness, and wide applicability. Among these, galvanized plates and galvanized steel plates are two common products. While they may seem very similar at first glance, are they completely identical? What are the differences between them in detail? We will delve into this question in the following discussion.

1. Definition Analysis

galvanized steel plates, as the name suggests, are metal products where a layer of zinc is applied to the surface of steel plates through a series of processes. Specifically, they refer to materials where steel plates (carbon steel or alloy steel) are used as the base material, and a zinc layer is applied to the surface through hot-dip galvanizing or electroplating processes. The base material thickness is typically ≥0.3mm, meeting the definition of ‘steel plate’ in the GB/T 2518-2019 standard. This zinc layer effectively prevents corrosion of the steel plate and extends its service life. For example, a 120g/m² hot-dip galvanized layer can last over 20 years in normal environments (refer to ISO 1461 standard).

galvanized plate, on the other hand, is often regarded as a shortened or generalised term for galvanized steel plate, referring to all types of plate materials with a zinc coating on their surfaces, where the base material may be steel plate, aluminium plate, or even copper plate. For example, galvanized aluminium-magnesium plates used in construction (with an aluminium base material) also fall under the category of galvanized plates, and the salt spray resistance of galvanized aluminium plates can reach three times that of galvanized steel plates (data source: American ASTM A792 standard).

2. Differences between galvanized steel plates and galvanized plates

Although galvanized steel plates and galvanized plates are similar in basic function, there are some subtle differences between them in terms of specific materials, applications, and production processes.

(1) Material Differences  

galvanized plates typically use iron plates as the base material, with a zinc layer formed on the surface through galvanisation to protect the iron plate from corrosion. galvanized steel plates, as the name suggests, use steel plates as the base material, which are also galvanized to enhance corrosion resistance. The primary distinction between the two lies in the difference in base materials, with the former using iron plates and the latter using steel plates, and galvanized steel plates having a broader range of material applications.

(2) Comparison of Manufacturing Processes

From a manufacturing process perspective, both galvanized steel plates and galvanized steel plates involve the critical step of galvanisation. However, in the actual production process, the two may employ slightly different processes due to varying application requirements. For example, hot-dip galvanizing and cold galvanizing are two common galvanizing methods, each suited for different scenarios and materials. Hot-dip galvanizing is typically used for larger steel plates, while cold galvanizing may be more commonly applied to precision components or parts requiring maintenance of original dimensional accuracy.

(3) Applications and Performance

In terms of applications, both galvanized steel plates and galvanized plates are widely used in various fields such as construction, transportation, and home appliances due to their excellent corrosion resistance. Whether used as roofing materials for buildings, exterior components for vehicles, or casings for home appliances, they perform exceptionally well. However, due to potential minor differences in manufacturing processes, their performance characteristics may vary in certain specific applications. For example, in scenarios requiring higher corrosion resistance or greater mechanical strength, galvanized steel plates treated with special processes may be necessary.

Core Performance Comparison (using hot-dip galvanizing as an example):

(All data is sourced from ASTM international standards and the 5th edition of the Handbook of Engineering Materials, published in 2021.)

3. Application scenarios

(1) Main areas of application for galvanized steel plates:

- Automotive industry: accounts for 35% of global galvanized steel plate consumption (data source: WorldAutoSteel), commonly used for car bodies, chassis and protective panels.

- Appliance housings: Refrigerators, washing machines, microwave oven housings, etc., with a zinc coating requirement of ≥60 g/m².

- Steel structure buildings: large factory beams, roof panels, and bridge protective components.

(2) Other advantageous applications for galvanized steel plates:

- galvanized aluminium plates: roofs and photovoltaic brackets (better weather resistance than pure galvanized steel plates).

- galvanized copper plates: electronic components and shielding covers (combining conductivity and corrosion resistance).

- galvanized aluminium-magnesium plates: wind turbine towers, coastal facilities, etc.

*Additional information*: The EU EN 10346 standard stipulates that galvanized steel plates must specify the base material type (e.g., HX340LAD+Z), while ordinary galvanized plates only need to indicate the zinc coating weight. This is an important distinction between the two.

4. How to select and purchase

When purchasing galvanized steel plates or galvanized plates, it is recommended to consider the following factors comprehensively:

(1) Usage environment

- Outdoor long-term exposure: Preferably use hot-dip galvanized steel plates or galvanized aluminium-magnesium plates;

- Indoor decoration or appliances: galvanized plates can be selected for a smoother and more aesthetically pleasing appearance.

(2) Mechanical Performance Requirements  

- For load-bearing capacity and welding performance: galvanized steel plates are more suitable;  

- For lightweight and corrosion resistance: galvanized aluminium or galvanized aluminium-magnesium plates can be considered.  

(3) Coating Quality  

- The coating should be uniform, dense, and free of drips or burrs;

- It is recommended to require suppliers to provide third-party test reports, such as salt spray tests and coating thickness tests.

(4) Standards and certifications

- Common domestic standards: GB/T2518, GB/T 2975;

- Common international standards: ASTM A653, EN 10346, JIS G3302.

5. Market trends and future prospects

With the rapid development of green buildings, smart manufacturing, and new energy vehicles, the market demand for galvanized materials has been increasing year by year:  

Construction industry: Increased demand for energy-efficient and environmentally friendly colour-coated galvanized steel plates.  

Automotive industry: The combination of lightweight design and corrosion resistance drives the upgrading of high-strength galvanized steel plates.  

Home appliance industry: Dual requirements for appearance and durability promote the optimisation of electrogalvanized products.

In summary, galvanized steel plates and galvanized plates can be broadly considered the same material—i.e., plates with a zinc coating on their surfaces. However, in a strict sense, there may be subtle differences between the two in terms of manufacturing processes, applications, and performance. Therefore, when selecting and using these two materials, we need to make comprehensive considerations and choices based on specific application scenarios and requirements.