Galvanized vs. Galvannealed Steel: A Sheet Metal Comparison

Last updated on December 11th, 2023 at 08:21 am

Unsure whether to choose galvanized steel or galvannealed steel for your sheet metal parts?

While these two popular steel types have many similarities, there are some differences to consider. Here, we’ll explore and compare galvanized and galvannealed steel and provide the information you need to choose the best one for your project.

Galvanized Steel

Galvanized steel is a type of steel that has been treated with zinc to enhance its corrosion resistance. After the steel is submerged in a liquid zinc solution at 850 degrees Fahrenheit, excess zinc is blown off the surface to create the desired thickness. The molecular bond formed by the zinc and steel makes galvanized steel highly durable and excellent at resisting corrosion.

Galvannealed Steel

Galvannealed steel is also galvanized, but the process of creating it doesn’t stop there. Once the steel has been galvanized, it is heated in an annealing oven at 1,050 degrees Fahrenheit. This process melts some of the iron and brings it to the steel’s surface, creating a strong, corrosion-resistant zinc-iron alloy.

Similarities between Galvanized Steel and Galvannealed Steel

Galvanized and galvannealed steel share many qualities, including:

  • Excellent rust resistance
  • Easy to form, punch, and laser cut
  • Similar pricing
  • Easy to paint

Differences between Galvanized Steel and Galvannealed Steel

Although galvanized and galvannealed steel are more similar than they are different, there are a couple of key differentiating factors to keep in mind when selecting a material.

Aesthetics

Galvanized steel has a bright, “spangly” appearance, whereas galvannealed steel is relatively dull. For this reason, galvanized steel is often preferred for parts that will be highly visible, such as solar panels. Galvannealed steel is better suited for internal parts (e.g., electrical components) that don’t have strict aesthetic requirements.

Durability

Both steel types are known for their excellent durability. However, the annealing treatment that provides galvannealed steel with its zinc-iron coating offers slightly superior durability. If your parts will need to withstand extreme conditions, galvannealed steel may be the better choice.

Important Considerations for Galvanized Steel and Galvannealed Steel

Whether you select galvanized or galvannealed steel for your sheet metal fabricated parts, there are a few factors to consider to ensure optimal results.

Cutting and punching can compromise corrosion resistance

When cutting or punching galvanized steel or galvannealed steel, the zinc plating is stripped from the cut edges, leaving exposed steel edges that are susceptible to rust.

For superior rust resistance, we recommend choosing cold-rolled steel for your parts and having the material zinc plated after sheet metal fabrication. (Be aware that this alternative will increase your cost and lead time).

Welding is a slow and careful process 

Galvanized steel and galvannealed steel release toxic fumes when welded, meaning all welding must be done in a well-ventilated area. These steel types are also prone to sparking and popping during welding, requiring us to perform the process slowly and carefully. If you need galvanized or galvannealed steel parts welded, these accommodations can add to your lead time.

Thick plates are difficult to source 

Chances are you won’t find galvanized or galvannealed steel readily available in thicknesses over 10 gauge. If you’re looking for either of these materials in a higher thickness, your cost and lead time will likely increase. In this case, you may be better off choosing an alternative material like cold-rolled steel that we can plate following fabrication.

Galvanized vs. Galvannealed Steel - Need Help Selecting the Right Material? 

At ASM, we do everything in our power to help you choose the best materials for your parts. We’re happy to answer questions you may have about galvanized steel, galvannealed steel, or any other material you may be considering.

Galvanized vs. Galvannealed Steel FAQ

Galvanized steel is treated with zinc, forming a protective layer against corrosion. Galvannealed steel undergoes an additional annealing process after galvanization, creating a zinc-iron alloy for enhanced durability and corrosion resistance.

Consider the aesthetic requirements and environmental conditions your parts will face. Galvanized steel, with its bright appearance, is suitable for visible parts like solar panels. Galvannealed steel's dull finish makes it ideal for internal components needing superior durability in harsh conditions.

Yes, both steel types can lose corrosion resistance at cut edges, leaving them vulnerable to rust. Welding these materials requires a well-ventilated area due to toxic fumes and demands a slow, careful process to avoid sparking. Additionally, thicker plates of galvanized or galvannealed steel are harder to source, potentially increasing cost and lead time.

For enhanced rust resistance, it's recommended to choose cold-rolled steel and apply zinc plating after fabrication, although this can increase cost and lead time. This process safeguards cut edges and minimizes susceptibility to rust.

At ASM, we specialize in helping clients choose suitable materials for their parts. Whether it's galvanized, galvannealed steel, or any alternative material, we provide guidance and address queries to ensure you select the best option for your specific project needs.

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