Zinc Coated Sheet Metal
Continuous hot-dip galvanizing produces a zinc coating on one or both sides of carbon steel sheet. The tightly bonded coating is ductile and serves as a sacrificial barrier to corrosion-causing elements.
The coating also serves as a lubricant during forming processes, allowing for more accurate forming and higher production rates than uncoated materials. It also provides a superior surface for painting, particularly with spray application.
Galvanized
The galvanizing process is one of the best methods for protecting steel from corrosion. It uses regular steel sheets or manufactured items that are dipped in a bath of molten zinc and then left to cool. This creates an outer layer of zinc that is metallurgically bonded to the steel. It’s a durable coating that is incredibly strong and offers a long lifespan for metal components used in harsh environments.
Zinc coatings are available in a wide range of thicknesses, surface qualities and applications. Continuous hot-dip galvanizing (CGH) provides a wide protection range from Z100 to Z600 and has the advantage of a tight bond between the coating and the steel substrate, making it suitable for forming and demanding corrosive environments. It also offers the benefit of a sacrificial anode, which means that even if the zinc coating is damaged or worn away in some places, the underlying steel will still be protected from corrosive elements.
Architects, engineers and building owners who choose to specify galvanized sheet metal are choosing an economical solution that will protect their investment. It’s important zinc coated sheet metal to consider the initial cost of steel galvanization and how that compares to other protective coatings. Hidden costs such as maintenance recoating and production loss due to the need for downtime should also be weighed against the cost of steel corrosion protection.
Another type of protective zinc coating is electroplating, which is more suitable for small, lightweight steel parts. This is done by passing the part through an electric current between the positively charged zinc ions and a negatively charged nickel electrode. The ions are reduced to create the zinc coating, and it’s typically rinsed and passivated to enhance corrosion resistance and appearance.
Electrogalvanizing is ideal for items that are too big or heavy for the hot-dip galvanization method. It can be used on items such as wires, nuts and bolts, and even cars. The sacrificial anode nature of the zinc allows these items to be used for years without corroding, and the protective zinc coating offers excellent longevity in most environments. This is why many manufacturers provide rust warranties for galvanized products. This is a good way to offer customers peace of mind and entice them to purchase your product. However, the high formability and moderate weldability of this coating make it unsuitable for some applications. It’s not recommended for items that will be exposed to chlorinated water, and it is not a good choice for fasteners with fine threads. Also, it’s not possible to achieve the same level of corrosion protection with electroplating that can be achieved with hot-dip galvanizing or thermal spraying. This is why it’s important to speak with a qualified professional before selecting the right zinc coating for your project.
Galvannealed
Galvannealed sheet metal is coated with a combination of zinc and aluminum, providing corrosion resistance similar to that of regular galvanized steel. The aluminum content in this coating makes it less sensitive to high temperatures, allowing it to be used in applications where flammability is a concern. This coating also offers better paint adhesion than regular galvanized steel.
Zinc coated sheet metal can be used in a variety of applications, both indoors and outdoors. This type of protection is ideal for applications that are subject to heavy wear and tear, as well as for environments with high humidity or saltwater exposure. This is one reason why it is used extensively in the automotive industry. In fact, the ‘body-in-white’ of a car uses about 80% galvanized steel.
The life span of a galvanized steel product depends on the environment, the thickness or coating weight, and other factors. In optimum conditions, galvanized steel can last for decades before showing signs of rust or corrosion. If galvanized steel is painted, the lifespan can be increased even further.
Hot-dip galvanizing involves dipping finished steel products into molten zinc. This allows the zinc to form a tight, durable layer that adheres to the surface of the steel. Unlike some other methods of galvanizing, hot-dip galvanizing provides complete coverage for the entire surface of the steel, including recesses and corners.
Pre-galvanizing is a method that is performed prior to the hot-dip process, and is used on materials with specialized shapes. It involves rolling the material through a cleaning agent to quickly prime it for galvanizing, followed by a dip into a pool of molten zinc. This is a great option for large scale, time-sensitive galvanizing operations, and produces a superior coating that is more uniform than the traditional hot-dip process.
Electrogalvanizing is another method of galvanizing that uses electrical currents to bond zinc to the steel. This method produces a thinner coating than the hot-dip process, but it is durable and effective in most environments. In addition to providing a more consistent coat, this method also prevents sideways creep of the zinc coating.
Post-Plate Chromate Treatments
This is a coating that can be applied after the galvanization and annealing processes, to provide additional corrosion resistance and improve paint or adhesive bonding properties. This is a galvanized steel supplier very common and cost-effective way to prolong the life of a zinc-coated steel product, particularly in harsh environments.
