Are you curious why some can persist in harsh environments for a long time while others quickly become rusty, even though they are both galvanized plates? In fact, the corrosion resistance of galvanized plates is not constant, and it is deeply influenced by various factors. Next, let's uncover the mystery of the five key factors that affect the corrosion resistance of galvanized plates.

01 Zinc layer thickness and uniformity

-The thickness of the zinc layer is the most direct factor affecting the corrosion resistance of galvanized plates. Generally speaking, the thicker the zinc layer, the longer the barrier protection time it provides.
-According to national standards, the thickness of the zinc layer on galvanized plates is usually between 5-25 μ m. The weight of the zinc layer per square meter is directly related to its thickness, with a corresponding increase in thickness as the weight increases.
-The uniformity of the zinc layer is equally crucial. Uneven zinc layer can lead to premature corrosion in local areas, significantly shortening the overall service life.

-In practical applications, it is necessary to select galvanized plates with appropriate zinc layer thickness based on the corrosiveness of the usage environment to ensure a balance between economy and durability.

02 Environmental conditions and exposure levels

-Environmental humidity is a key parameter that affects the corrosion rate of galvanized plates. When the relative humidity exceeds 60%, the corrosion rate of the zinc layer will significantly accelerate.
-Corrosive media such as sulfur dioxide in industrial atmosphere, chloride ions in coastal areas, and snow melting agents in northern winter can significantly accelerate the corrosion process of galvanized plates.
-Temperature changes can also affect the corrosion rate. Usually, for every 10 ℃ increase in temperature, the corrosion rate increases by about 1-2 times. Frequent alternation of dry and wet environments can also accelerate the corrosion process.

-In practical applications, it is necessary to select galvanized plates with corresponding protection levels for different environmental conditions to ensure their long-term performance.

03 Surface state and composition of substrate

-The chemical composition of the substrate can affect the formation and quality of the galvanized layer. Excessive content of elements such as silicon and phosphorus can lead to excessive growth of the zinc layer, forming a loose and porous coating.
-The cleanliness of the substrate surface directly affects the adhesion of the zinc layer. Residual oil, oxide skin, or impurities can hinder the normal formation of the zinc iron alloy layer and reduce the protective effect.
-The surface roughness of the substrate can also affect the adhesion and uniformity of the zinc layer. A suitable rough surface helps to improve the bonding strength of the zinc layer.

-Therefore, strict control of the surface state and composition of the substrate is an important prerequisite for ensuring the corrosion resistance of galvanized plates.

04 Galvanizing process and post-treatment

-The control of hot-dip galvanizing process parameters directly affects the quality of the galvanized layer. The temperature of the zinc solution, immersion time, and extraction speed all affect the structure and thickness of the zinc iron alloy layer.
-The cooling method after galvanizing can also affect the microstructure and properties of the zinc layer. Different cooling rates can lead to the formation of different phase compositions in the zinc layer, thereby affecting its corrosion resistance.
-The passivation treatment after galvanizing can significantly improve the corrosion resistance. Treatment methods such as chromate passivation and chromium free passivation can form a protective film on the surface of the zinc layer, delaying the start time of corrosion.

-Advanced galvanizing process control and appropriate post-treatment are technical guarantees for improving the corrosion resistance of galvanized plates.

05 Mechanical damage and protective measures

-The galvanized layer may suffer mechanical damage such as scratches, collisions, etc. during transportation, processing, and installation, which can damage the integrity of the zinc layer and form the starting point of corrosion.
-The cutting edge and drilling position are the most susceptible areas to corrosion of galvanized plates, and the zinc layer protection effect in these areas is the weakest, requiring additional protective measures.
-Regular inspection and maintenance can effectively extend the service life of galvanized plates. Timely detection and handling of local damage can prevent the expansion and exacerbation of corrosion.

-Avoiding direct contact with dissimilar metals during use to prevent electrochemical corrosion is also an important measure to protect galvanized plates.

With the continuous advancement of technology and the sustained development of industry, the requirements for the corrosion resistance of galvanized plates are also increasing. In the future, we look forward to conducting in-depth research on these 5 factors that affect the corrosion resistance of galvanized plates, continuously improving and innovating, and developing galvanized plate products that are more corrosion-resistant and have better performance. At the same time, we also hope that users and manufacturers can pay attention to these factors and jointly promote the development of the galvanized plate industry, so that galvanized plates can play a greater role in more fields.