The type of metal you choose affects the longevity, durability, and type of maintenance your product or building may require. It also affects the budget and costs associated with the project. Knowing the various metals on the market can help you determine which metal is best for your metal product or construction. If you are considering using this type of metal, read on to learn more about galvanized steel.

What is galvanized steel?

Galvanized metal is metal that has undergone a galvanizing process. Galvanizing is the process of applying a thin coating of zinc to different types of metals. There are different methods of galvanizing metals, including hot-dip, pre-galvanized, and electro-galvanized.

Galvanized steel is one of the most popular grades because of its extended durability, the strength and formability of steel, and the corrosion protection of a zinc-iron coating. Zinc protects base metals by acting as a barrier to corrosive elements, and the sacrificial nature of the coating results in long-lasting and high-quality steel products.

Different Process For Galvanized Metal

The primary method of galvanizing is hot dip galvanizing. In this method, steel or iron is immersed in a molten bath of zinc, which is maintained at a temperature of around 860°F (460°C). This molten bath initiates the metallurgical bond between the zinc and the receiving metal. After the metal is removed from the bath and exposed to the atmosphere, a reaction occurs where pure zinc mixes with oxygen to form zinc oxide. Zinc oxide further reacts with carbon dioxide and forms zinc carbonate, which constitutes the final protective coating on the material. A telltale sign of hot-dip galvanized material is the presence of a crystal-like pattern on the surface, sometimes referred to as "sequins".

The new coated material can be processed and processed in a similar manner to the uncoated material. Galvanized steel can be used for high temperature applications up to 392°F, but use above this level will cause the zinc carbonate layer to peel.

Electrogalvanizing

This is the most unique method, and electrogalvanizing does not involve dipping the material into molten zinc buckets. Instead, an electric current is introduced into an electrolyte solution applied to the steel, reducing the positively charged zinc ions to zinc metal, which is then deposited on the positively charged steel. This method is usually carried out in the first stage of production.

Electroplating is an economical, versatile and effective method of applying protective coatings to small steel components. It is the most widely used method of applying metallic zinc coating to small fasteners, especially those with fine threads.

In general, there is an economic upper limit to the quality of zinc coating that can be applied by electroplating, so it is generally not used for outdoor exposures without supplemental coatings.

Pre-galvanizing

This is a method similar to hot dip galvanizing, but performed in the first stage of production. Pre-galvanizing is a process that involves coiling sheet metal through a cleaner to quickly prepare the material for galvanizing. The metal then passes through a molten pool of liquid zinc and is immediately recoiled. The main advantage of this method is that the steel coil can be galvanized quickly and on a large scale with a more uniform coating compared to the traditional hot dip method.  

Thermal Spray

Thermal spraying or metallizing is the process of spraying semi-molten zinc, other metals or their alloys onto finished products using wire or powder heated by a flame, arc spray or plasma heat source.

The advantage of zinc spraying is that zinc coatings up to 250 μm thick, equivalent to 1500 g/m2 can be applied manually or mechanically, and the process can be carried out in the factory or on-site. The steel surface must be sandblasted and the coating usually does not extend to the inner surface. In addition, it can be damaged or limited application on sharp edges, narrow corners, holes and poor finish. The resulting zinc coating provides barrier and cathodic protection to the underlying steel in the same manner as galvanized coatings.

In most cases, thermal spraying is more expensive than batch hot-dip galvanizing of equivalent sections, but these processes are complementary and used in tandem on large structures.

WanJuan Steel is one of experienced galvanized steel coil suppliers. If you are looking to purchase galvanized steel, or you want galvanized metal formed or cut for your project, we are here to help you. Read more to inquire about purchasing china color coated steel coil or our metal services.