The purpose of hot-dip galvanizing is to protect the material from corrosion by creating a layer of zinc that acts as a protective coating. The process of hot dipping is to submerge the metal into a bath of molten zinc, which metallurgically bonds itself to the material (usually steel). This then protects the material against external elements such as: humidity, moisture, sodium chloride, and acid. The hot-dipped galvanized steel can be used across a wide range of industries, for things such as: roofing, structural beams, automotive bodies, rebar in cement, metal fences, and electrical pylons.
Contact us to discuss your requirements of Hot Dip Galvanized W-Beam Guardrail. Our experienced sales team can help you identify the options that best suit your needs.
This article will discuss hot-dip galvanizing, how it works, its purpose, uses, advantages, and disadvantages.
The hot-dip process creates steel with a thin protective layer of zinc by dipping the steel into hot molten zinc. During the dipping, the zinc reacts with the steel to make a zinc-iron layer which can protect against corrosion. Hot-dip galvanizing is also referred to as galvanization and galvanizing.
The purpose of hot-dip galvanizing is to form a protective iron-zinc coating on the surface of the steel to protect against corrosion. The coating should cover both internal and external sections of products which are hollow or shelled. The galvanization coating is a sacrificial coating that reacts with the environment to protect the steel beneath it. Hot-dip galvanization also leads to an impact and abrasion-resistant surface when compared to other protective treatments.
With any parts to be galvanized, it is easier for any welding to be completed before galvanization, as galvanized steel is harder to weld than pre-treated steel. For the galvanization process, the first step is to degrease and clean the surface of the steel of any residues or particles on the surface. This allows the coating to react fully and adhere to the steel. The best method of cleaning is to submerge the part into an alkaline or acid solution and then rinse with cold water. After cleaning, a coating of flux is applied by dipping the part into a 30% zinc ammonium solution at 65&#;80 °C. This removes any remaining oxide from the surface to allow the molten zinc to react with the steel. The part is then dipped in the molten zinc at approximately 450 °C for approximately 4&#;5 minutes depending on the thermal inertia of the part. After the hot dip, the now galvanized steel can be air-cooled or quenched if required.
The temperature at which steel should be galvanized is 450 °C. The zinc needs to be at this temperature to allow a metallurgical reaction to occur between the zinc and the steel. Any colder and the wetting of the steel would not be optimal and a significant increase in temperature would begin to soften the steel. Additionally, hotter temperatures could cause the part to warp if there are significant internal stresses already in the steel before hot dipping.
No, hot-dip galvanizing and galvanizing processes are not the same. While both achieve the same result they both have different processes. The other processes for galvanizing are galvannealing and electro-galvanization. The galvannealing process is the same as the galvanization process, however after the hot dipping the part is heated up to over 1,050 °C and then air cooled. The annealing part of galvannealing encourages further reaction between the steel and zinc. In electro-galvanization, the steel is electroplated with zinc using zinc salt. This leaves behind a much thinner layer of zinc compared to regular galvanization.
The thickness and silicon content of the steel being coated will dictate the minimum thickness of coating required. The ASTM A123 specification states that hot-dip galvanization should produce a coating between 1.4 to 3.9 mm thick for the best protection. The silicon content of the steel matters because an increase in silicon content makes the zinc more reactive and therefore a thicker coating will be required to maintain the longevity of the part. A thicker steel will also produce a thicker coating. As there is more iron available in a thicker steel part, more zinc will be required to react with the iron. This will produce a thicker protective layer.
Yes, hot-dip galvanization can result in warping. When the steel is hot dipped it heats the steel which can allow the internal stresses in the steel to warp the part. To reduce the chances of this happening the steel can be stress relieved/tempered to reduce the internal stresses of the material.
Hot-dip galvanized steel is used where steel is being used in a corrosive environment. This could be in salt-laden air or marine applications, but could also apply when steel is embedded in soil, concrete, or water. Galvanized steel is a versatile metal that is used in car bodies, bikes, fasteners, structural beams in buildings, rebar in concrete, metal fencing, and electrical pylons.
Want more information on Galvanized Highway W Beam Guardrail? Feel free to contact us.
Hot-dipped galvanized steel is used in just about every industry. Hot-dipped galvanized steel is used in the automotive, construction, telecommunications, oil & gas, and aerospace industries, for any application in which steel is in a corrosive environment.
Table 1 below describes the properties and benefits of hot-dipped galvanized steel:
Galvanizing is a manufacturing process where steel or iron is coated with zinc. Galvanized steel, therefore, is zinc-coated steel. There are several galvanizing methods, with the most common method being hot dipped galvanization.
Benefits of Galvanized Steel
Galvanized steel is one of the most popular steels because it is rust-resistant and more affordable than most treated steels. And, it doesn&#;t require any maintenance or refinishing. Since the zinc coating protects it from the elements, the steel can last for 50 years in temperate environments. Even with severe weather exposure, galvanized steel can last for over 20 years.
Galvanizing Methods
As mentioned, there are several galvanizing methods including galvannealing, pre-galvanizing, electrogalvanizing, and hot-dip galvanizing. Hot-dip galvanizing is the most popular, which we will explain in more detail. But first, let&#;s briefly cover the other three.
What is the Hot Dip Galvanizing Process?
As the name suggests, the steel is dipped in hot, molten zinc. While the steel is inside the molten zinc, a metallurgical reaction occurs between the iron contained inside the steel and the hot zinc. The reaction is known as a diffusion process. The diffusion process is when the coating collects perpendicular to every surface and creates a uniform thickness.
When the steel is removed from the zinc bath, it reacts with the oxygen in the air to form zinc oxide. It then reacts to carbon dioxide and forms the final protective coating of zinc carbonate. Ultimately, the steel has a corrosion-resistant, multi-layered coating of zinc metal and iron-zinc alloy.
Hot-dipped galvanized steel has a fairly distinct appearance compared to other galvanized steel. It has a mottled, crystalline-like pattern known as a &#;spangle&#; pattern.
What is Hot Dip Galvanizing Used For?
Galvanized steel is very versatile. It is used in a wide range of industries, including agriculture, automotive, construction, solar, telecommunication, and many more. Because of its resistance to corrosion, galvanized steel is preferred in applications that may be exposed to moisture or the elements.
All kinds of screws, nuts, bolts, tools, and wires are galvanized to increase their durability. Entire steel frame buildings use galvanized steel to support the bulk of the structure. Fences, roofs, staircases, and more are often made with galvanized steel. As stated, galvanized steel is very versatile! Galvanized steel offers more than improved functionality; it also offers aesthetic appeal. Many architects incorporate galvanized steel in their designs. The shiny finish gives a clean, modern feel that is popular in contemporary architecture.
Hot Dipped Galvanized vs Galvanized Steel
In summary, hot-dipped galvanized steel is a type of galvanized steel. The hot-dip galvanizing process is relatively cheap, and the resulting product is very durable and versatile. Hot-dipped galvanized steel is most often used in applications that will be exposed to the elements as it is highly corrosion-resistant.
If you are looking for more details, kindly visit highway beam.