Galvanized vs. Galvannealed Steel: A Sheet Metal Comparison (Updated for 2025)

Last updated on March 7th, 2025 at 09:15 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.

Comparing Paint and Powder Coat Adhesion on Galvanized vs. Galvannealed Steel

Both galvanized and galvannealed steel can be painted or powder coated, but their surface properties significantly impact adhesion and durability. Choosing the right finishing method for your application requires understanding how each material interacts with coatings.

Galvanized Steel: Requires Extra Preparation

Galvanized steel has a smooth, spangled zinc coating that provides excellent corrosion resistance but poses challenges for paint and powder coat adhesion. The smooth surface prevents coatings from properly gripping the material, which can lead to peeling or flaking over time.

To improve adhesion on galvanized steel, additional surface preparation is required:

• Chemical Treatments: A zinc phosphate pretreatment or helps the coating bond effectively.
• Surface Abrasion: Lightly sanding or media blasting the surface can create texture for better adhesion.
• Degreasing & Cleaning: Removing oils and contaminants with a solvent-based cleaner ensures a clean base for coating.

Even with these steps, galvanized steel may still experience paint peeling over time, especially in high-moisture environments.

Galvannealed Steel: Superior Adhesion

Unlike galvanized steel, galvannealed steel undergoes an annealing process that creates a zinc-iron alloy coating. This results in a matte, porous surface that naturally promotes strong adhesion for both paint and powder coatings.

Because of its superior surface properties:

• Galvannealed steel does not require extensive surface preparation beyond basic cleaning.
• It is the preferred choice for automotive and appliance manufacturing, where high-quality painted finishes are required.
• Powder coat and paint adhere more evenly and last longer compared to galvanized steel.

Which Should You Choose?

• If your parts require a high-quality painted or powder-coated finish, galvannealed steel is the better option due to its natural adhesion properties.
• If you must use galvanized steel, be prepared for extra surface preparation steps to ensure coating durability.
• For uncoated parts exposed to harsh environments, galvanized steel’s thicker zinc layer offers better corrosion protection.

By selecting the right material and finish combination, you can maximize performance and longevity while reducing rework and adhesion issues.

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.