Galvanized sheet metal is a steel or iron product that has a protective zinc coating to prevent rusting. According to the GalvanizeIt! Online Seminar from the American Galvanizers Association, this method provides corrosion protection, durability under harsh conditions, a long lifespan, versatility, availability, and sustainability.
See how sheet metal fabrication shops, like Kaempf & Harris, achieve galvanized sheet metal for everyday projects, from construction and transportation to agriculture and recreation:
Electrogalvanizing. This process is when a layer of zinc is bonded to stainless steel using electroplating, which is when a fabricator runs a current of electricity through a saline-and-zinc solution with a zinc anode (an electrode through which conventional current flows into a polarized electrical device).
In electrogalvanizing, the polarized electrical device is a steel conductor.
Compared to hot-dip galvanizing, this sheet metal technique offers lower thickness deposits for comparable to increased performance, a broader conversion coating availability for color options, and brighter deposits.
Hot-dip galvanizing. This is the most popular sheet metal technique for galvanization. The process submerges metal parts in a bath of molten zinc to protect the metal and occurs in three different ways:
- The zinc coating, when intact, prevents corrosive substances from reaching the underlying steel or iron.
- It acts as a sacrificial anode, which is the main component of a galvanic cathodic protection (CP) system used to protect buried or submerged metal from corrosion. This means that if the coating is scratched, the exposed steel or iron will be protected by the remaining zinc.
- The zinc protects its base metal by corroding before iron.
Hot-dip galvanizing limits a steel or iron product’s exposure to the natural elements, protecting it from corrosion and oxidation. This sheet metal technique is also economical, can be performed within minutes, and covers hard-to-reach areas of complex product shapes.
Metallic/thermal spraying. Metallic spraying is the process of covering a sheet metal product with a metallic coating using a spray of molten particles.
According to Corrosionpedia, “a convergence of business leadership, modern digital technology and industry publication experience”, fabricators first subject the iron or steel “to a high degree of heat to achieve a molten state. The molten metal is then atomized into small particles and sprayed outward onto a surface.
The molten particles [don’t] heat the surface because the heat of a particle is proportional to its size. On contact, the particle flattens out and adheres to the surface as it hardens.”
Flame and arc spraying are sub-methods of this technique, adding anti-corrosion layers and thermal barriers. Other benefits of metallic/thermal spraying include increased durability, wear resistance, modified electrical properties, and additional protection to damaged materials.
Sherardizing. Also known as vapor or dry galvanization, sherardizing is named after British metallurgist Sherard Osborn Cowper-Coles.
It involves heating steel products up to 932 degrees Fahrenheit in a closed rotating drum that contains metallic zinc dust and potentially an inert filler, such as sand.
At temperatures above 572 degrees Fahrenheit, the zinc dust evaporates and diffuses into the steel substrate forming a diffusion bond.
This method is ideal for small sheet metal parts and parts that require coating of inner surfaces, as the product must be smaller than the rotating drum.
A huge benefit to this sheet metal technique is that no hydrogen is involved. Therefore, hydrogen embrittlement (when steel becomes brittle due to the introduction and subsequent diffusion of hydrogen into the metal) is excluded.
If you're ready to inquire about galvanized sheet metal for your next project, contact the fabricators at Kaempf & Harris in Frederick, Maryland. If you want to perform more research on this sheet metal product, click below to download our guide: