Steel is an essential component for any industry that requires load-bearing capabilities. However, to maintain their usefulness, they must be protected from corrosion. For instance, for steel gratings to continue serving their intended purpose efficiently, one of the critical requirements is ensuring their protection from corrosion.
What is corrosion?
Corrosion of steel can be defined as deterioration due to electrochemical reactions with the metal and its environment. Especially for steel, when iron rusts in metal oxides. In most cases, both oxygen and water must be present in order for corrosion to occur.
The different phases of the corrosion process in steel can be distinguished and analyzed individually.
· The surface anode region is attacked and iron ions enter the solution.
Once the electron flow is initiated, the electrons are liberated and move through the metallic structure to reach the cathodic center of the surface. Once arrived at the cathodic center, the electrons react with oxygen and water molecules to form hydroxyl ions.
They react with iron ions in the anode to form ferrous hydroxide.
The process results in the formation of "red rust," which is a form of iron oxide.
The summation of this chemical reaction is as follows: to produce a similar content, the original text information must be rearranged appropriately.
The chemical equation Fe + 3O2 + 2H2O can be represented as the formation of hydrated iron oxide (rust), which is commonly produced when steel comes into contact with both oxygen and water. This reaction can be written as 2FE2O3H2O, where the steel and oxygen molecules combine with water molecules to create the recognizable red-brown substance known as rust. This process occurs naturally over time, but can be accelerated in certain conditions, such as exposure to salt water or high humidity. Despite its undesirable appearance, rust can actually provide a protective layer for the underlying metal, preventing further corrosion.
The presence of water, particularly in humid environments, is a contributing factor in the occurrence of corrosion. When exposed to salt water, corrosion is accelerated. It's important to note, however, that corrosion can also occur without the presence of water. In such cases, iron oxides in the atmosphere can result in dry corrosion. Elevated temperatures can further hasten the corrosion process.
What is the type of corrosion?
There are many types of corrosion. Here are some of the more common examples:
• Uniform attack corrosion - also known as general corrosion, which causes deterioration of the entire exposed surface of the steel. This is the more common type of decay.
Electrolytic Corrosion - Galvanic corrosion or dissimilar metal corrosion occurs when steel comes into contact with another metal in a corrosive electrolyte.
When the protective coating of a specific area of steel is destroyed, the consequence is the occurrence of pitting corrosion. This occurrence happens when the area becomes the anode while the remainder of the metal becomes the cathode, thereby generating a localized galvanic response.
Crevice corrosion Similar to pitting corrosion, crevice corrosion is localized, generally in a stagnant microenvironment, where acid environments or depletion of oxygen in the crevices can lead to corrosion.
• Intergranular Corrosion - Intergranular corrosion occurs along metal grains or grain boundaries.
Types of Steel Finishes
Surface treatment is a more effective way to prevent corrosion of steel. Here are some of the more common steel maker uses you'll see:
Hot Dip Galvanizing - This method of galvanizing can be used on steel of all shapes and sizes and involves dipping the steel in a zinc bath at temperatures up to 450°C. Steel galvanized in this way is well protected from corrosion and extreme weather, a particularly popular method for plumbing-related applications. For example, after the steel grating is hot-dip galvanized, its life will be extended, and the operation will be more assured.
If you want to enhance the visual appeal and increase the corrosion resistance of steel surfaces, you can apply specially formulated primers. One of the most widely used primers for this purpose is zinc phosphate primer. By using this type of primer, you can protect the steel from rust and other forms of corrosion, while also improving its overall appearance. It is an effective way to prepare surfaces for painting or other finishes, ensuring that they remain strong and durable for a long time.
Utilizing static electricity or compressed air, a specialized powder material is applied to the surface of the steel with a delicate technique known as chemical coating. This powder is then melted to produce a smooth, protective film that shields the steel from corrosion and UV damage. Additionally, this treatment enhances resistance to spalling, scratching, and cracking.
Zinc Spray Metallization - While it doesn't provide the exact same protection as hot dip galvanizing, this technique is very effective against corrosion and is popular for its smooth finish. Because this is a "cold process", there is no risk of twisting the metal, which makes it ideal for use on ornate metal parts such as railings and fences.
