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When we talk about galvanized steel, we mean any steel product that is coated with a protective layer of zinc. Its main role is to protect the material against corrosion over time.
This type of protection is widely used in industry, metal construction and various technical applications. The durability of the material is essential in these fields of use.
By applying zinc, steel gains increased corrosion resistance over time. This resistance is maintained even under difficult operating conditions.
By galvanized steel we mean a very wide range of metal products used in various industrial fields. These include galvanized sheet metal, galvanized profiles and small metal parts used in assemblies.
This category includes frequently used I, H, C, U, square, round and angle profiles. Also included are bolts, clamps, flanges and other fastening components.
In principle, almost any material made of steel can be coated with a protective layer of zinc. This is only possible if the material is properly prepared.
The choice of galvanizing type always depends on how the final product will be used. The installation environment and the technical requirements of the project also matter.
Depending on the needs, one can opt for electrolytic galvanizing or hot-dip galvanizing. Each method has specific characteristics, advantages and limitations.
Galvanized Steel and Galvanizing Methods
In the case of galvanized steel, there are two main methods of applying the protective zinc layer. These methods are used depending on the technical requirements of the products.
The galvanizing methods used are electrolytic galvanizing and hot-dip galvanizing. Each method is chosen depending on the application and the type of parts.
Electrolytic galvanizing involves depositing a thin and uniform layer of zinc on the surface of the parts. This method is used especially for parts that need to be joined, threaded or assembled with precision.
Hot-dip galvanizing involves immersing the parts in a bath of molten zinc. This method offers the best protection against corrosion.
However, hot-dip galvanizing has certain aesthetic and structural limitations depending on the shape of the parts. These aspects must be taken into account during design.
Choosing the correct galvanizing method is essential to ensure the longest possible service life of steel products. It also prevents problems from occurring during subsequent use.
Characteristics of Electrolytic Galvanizing
Electrolytic galvanizing is carried out through an electrolysis process at room temperature. This process does not require heating the zinc bath.
The product to be galvanized acts as a cathode in the process. Zinc acts as an anode during the application of electric current.
By applying the electric current, a layer of zinc is deposited evenly on the surface of the part. This process allows good control of the deposition.
The layer obtained through electrolytic galvanizing is thin and uniform over the entire surface. The thickness of the layer can be controlled by the time the parts are kept in the bath.
Typically, the thickness of the zinc layer varies between 7 and a maximum of 25 microns. This ensures a pleasant aesthetic appearance.
At the same time, electrolytic galvanizing provides good dimensional accuracy for the treated parts. This characteristic is important for assembly parts.
This method is preferred for fastening components, bolts, flanges and parts that require a controlled zinc layer.
An important advantage is that the parts do not deform, because the process takes place at normal temperature. The original shape of the parts is preserved.
The major disadvantage is the reduced protection against corrosion, compared to hot-dip galvanizing. This aspect limits its use in aggressive environments.
Characteristics, Disadvantages and Requirements of Hot-Dip Galvanizing
Hot-dip galvanizing involves heating the zinc above its melting point, the zinc bath having a temperature of approximately 450–460 degrees. The parts are completely immersed in molten zinc, after having previously undergone a chemical cleaning and degreasing process.
Before galvanizing, all traces of grease, paint, dirt or workshop chalk must be removed. If these impurities remain on the surface of the parts, the zinc will not adhere properly and the protection will be compromised.
Through hot-dip galvanizing, the parts receive a protective layer of zinc with a thickness ranging between 50 and 150 microns. This thickness ensures high resistance.
This method offers the best protection against corrosion for metallurgical products. It is considered the most efficient solution available.
An important disadvantage is the possibility of warping occurring in large, flat parts. This risk must be taken into account during design.
Also, the layer obtained is not uniform from an aesthetic point of view. Drips, icicles or color differences may appear .
After cooling, these differences can become visible on the surface of the galvanized parts. The aesthetic appearance is less controllable.
If the hot-dip galvanized parts are to be subsequently painted, surface finishing is necessary. This is essential for electrostatic powder coating, where any defect becomes visible.
Service Life, Warranty and Operating Conditions
The service life of hot-dip galvanized steel products is, under normal operating conditions, approximately 25 years.
This duration is valid for environments without chemical pollution and without saline influence.
In chemically polluted environments, the first signs of corrosion can appear after approximately 10 years.
In saline environments, the first signs of rust usually appear after 12-14 years, chemical pollution being more aggressive than the saline environment.
The service life of electrolytically galvanized steel products is shorter and depends directly on the thickness of the applied zinc layer.
Under normal indoor conditions, without excessive humidity or aggressive factors, the protection is maintained for a good period of time.
On the other hand, outdoors or in difficult environments, corrosion can appear more quickly on the surface of the parts.
Electrolytic galvanizing is used especially for small parts and fastening components where precision is important.
This method is not recommended for structures directly exposed to rain, humidity or aggressive chemical substances.
Operating Conditions and Limitations of Galvanizing
For hot-dip galvanizing, the parts must be fitted with hanging and venting holes. This is necessary for the safety of the process.
Structures made of pipes or closed profiles require proper venting. Hermetically sealed structures cannot be galvanized.
There is a risk of cracking or explosion in the molten zinc bath. This risk occurs in the absence of venting.
Any mechanical intervention on galvanized parts, such as cutting, welding or bending, leads to deterioration of the protective layer and voids the warranty.
Repairs with zinc-rich spray or paint do not restore the original protection. Hot-dip galvanizing cannot be redone locally.
The repaired areas will be the first where rust appears over time. This reduces the service life of the product.
Galvanized steel represents one of the most efficient solutions for corrosion protection. Hot-dip galvanizing is the highest-performing method.
Compliance with technical requirements and the correct choice of method are essential. These ensure the maximum service life is achieved.
If you need galvanized products, protected against corrosion, we look forward to your requests. These can be sent by email to office@h-metal.ro or via WhatsApp at 0749249007.
