Guide to Galvanized Steel: Benefits, Uses, & Process
September 23, 2021 | Categorised in: Steel 101
When choosing building materials for a project, there’s a lot of factors to consider. For environments such as outdoors where metal needs to be resistant to rusting and corrosion, steel is a great candidate. However, not all steel is rust-resistant. Stainless steel and galvanized steel are both types of steel that are used for their ability to withstand rusting and corrosion.
What is galvanized steel?
Compared to stainless steel, which changes the chemical composition of steel (by adding chromium), galvanized steel is simply a coating on top of the original steel. The coating that is applied is made of zinc, which forms a barrier between the steel and moisture in the air, effectively sealing it from elements that can lead to rusting. The zinc layer is softer and sacrifices itself to protect the metal inside from scratches, corrosion, and more. Galvanized steel also has a very identifiable “spangled” pattern with small lighter and darker spots.
Benefits of galvanized steel
As mentioned above, galvanized steel’s primary benefit is its rust and corrosion resistance. In addition to that, galvanized steel also lasts a long time (an estimated 50 years in an average environment and 20 years in an environment with lots of exposure to water) and requires little to no maintenance. Beyond keeping costs low during its lifetime, galvanized steel also has very low upfront costs compared to other treated metals and much less than other options for rust resistance. Even more, the process — which we’ll discuss below — is very quick and can be completed start-to-finish in half a day.
Uses for galvanized steel
Because the benefits of galvanization are so valuable and applicable to so much of steel’s uses, there are almost limitless applications for it. From items as small as nuts and bolts that need to withstand outdoor weather conditions to bike frames, ladders, and car bodies, galvanized steel helps to extend the lifetime and minimize maintenance required. The use of galvanized steel has become very common particularly in the agriculture, automotive, and construction industries that need to have reliable materials that can last decades in all kinds of weather and outdoor conditions.
Now that we understand why galvanized steel is useful for a wide variety of applications, we need to understand how it’s done. The two primary methods for galvanizing steel are hot-dip galvanization and electrogalvanization.
The more common of the two techniques, hot-dip galvanization (as the name suggests) involves dipping the piece of metal into molten zinc to form the layer on the surface. Before that can be done, however, the steel has to be prepared. It’s usually cleaned with a degreasing solution prior to being pickled in diluted sulfuric acid. It’s then fluxed to make sure the surface is clean before dipping into the molten zinc vat. The final step is to let the steel cool and inspect to make sure the zinc coating is evenly applied and doesn’t have any damage.
In certain applications such as steel used for car bodies, galvanizing is required but the thick layer provided by the hot-dip method causes issues with paint adhesion. Instead, they use electrogalvanization to get the same effect but with a thinner coat of zinc. The process involves a mixture of saline and zinc rather than molten zinc, which the metal (in this case, car body) is dipped into. An electrical current is then run through the tank and mixture, causing the zinc to be bonded to the steel’s surface and form the protective galvanized layer.
Galvanized steel vs. stainless steel
We mentioned that stainless steel can also be used for resistance to corrosion and rust, but not all of galvanized steel’s benefits carry over to stainless steel. For instance, stainless steel is much more expensive than galvanizing (usually four to five times more). The drastically higher price is a factor of the added chromium to the alloy, which also makes the steel stronger and more corrosion resistant than simply galvanizing. This is useful for very extreme environments, but for the majority of land-based and more common applications, galvanized steel will be the better choice simply because of the cost, both initial and for upkeep.
Protect your projects today
Galvanized steel is invaluable because of its characteristics and ease of production. Across a wide range of industries and applications, it is relied on to be dependable and have longevity. For this same protection, get in touch with us today to request a quote for galvanized steel today.