Galvanized steel and aluminum are both manufacturing materials loved and used by Xometry customers, but they have very different properties that manufacturers should be aware of before choosing between the two. Let’s take a look at these two popular metals, their uses, pros and cons, and how Xometry can help you when it comes to using them for your business.

What is Galvanized Steel?

Galvanized steel refers to steel that has been hot-dip coated, electroplated, or mechanically plated—among other methods—with zinc, which protects it against corrosion. This process is called galvanization. Treating the steel in this way provides it with an ionic barrier that will sacrifice itself and prevent the steel from rusting, and that’s why galvanized steel has a long environmental lifespan.

Due to its durability and corrosion resistance, galvanized steel is used in an impressive number of sectors and applications. Some of these include outdoor equipment (canopies, handrails, street furniture), adding corrosion resistance to parts (nuts, bolts, washers), being used in phone networks and power equipment boxes, and making pipes, and agricultural equipment (gates, barn components, livestock handling equipment).

What Does Galvanized Steel Look Like?

Galvanized steel takes on distinctive appearances resulting from the application technique, in which the texture and grain formation in the zinc coating will differ markedly by the method. The surface has a gloss-metallic silver-gray color, smooth and uniform when freshly hot-dipped. Over time, the coating will develop a dull, matte finish. The surface of galvanized steel may also have a fine crystalline pattern, known as a "spangle". This spangle effect can vary in size and intensity, ranging from small and tight to large and visible.

When electroplated, the surface can show large regions of crystallization spangle which are generally more evident than in hot-dip plating. These result from the progressive crystal growth that is more orderly than the faster, hot-dip-formed surface. Figure 1 below shows what galvanized steel looks like:

What Is Galvanized Steel Used For?

Galvanized steel is used for a strikingly wide range of applications due to its durability and corrosion resistance. It is commonly used in the construction of outdoor equipment such as: handrails, canopies, street furniture, power/light poles/pylons, and cladding. Additionally, galvanized steel is used to add corrosion resistance to nuts, bolts, washers, and nails for moderately corrosive environment applications. Galvanized steel pipes are used in various industries, especially when plastic piping is not strong enough or suitable for the application. In addition, hot-dip galvanized steel is often used in phone networks and power equipment boxes. 

What Are Examples of Galvanized Steel?

Galvanized steel is widely used in construction, transportation, energy, agriculture, household equipment, street furniture, and more. Examples of galvanized steel items are listed below:

1. Widely used in chassis, suspension, and wet-area components. 
2. Galvanized steel fasteners, such as: bolts, nuts, screws, washers, and nails, are widely used in most industry sectors. The zinc coating on these fasteners prevents rust and corrosion. 
3. Galvanized steel pipes and tubing are commonly used in plumbing, irrigation, electrical conduits, and various industrial fluid/gas/powder transport applications. 
4. Used to manufacture agricultural equipment like: fencing, gates, barn components, and livestock handling equipment. 

What Are the Advantages of Galvanized Steel?

1. Galvanized steel offers considerable advantages in various applications, such as:
2. It has a low initial cost and excellent value for money because it can last a long time
   Steel can hold its own against environmental factors or mechanical damage during handling, storage, transport, and erection, especially with the added zinc coating
3. You can make complex parts and structures with it because it’s malleable, ductile, and weldable, and environmentally stable, thanks to the zinc coating which is the most effective corrosion inhibitor available

What Are the Disadvantages of Galvanized Steels?

Galvanized steel does, however, have a few disadvantages to consider. These drawbacks are listed below:

1. While it’s protected against rust, it’s not fully immune to corrosion. Some aggressive environments, poor design, or minor mechanical damage could cause some corrosive decay
2. It can be more expensive than other options like paints or powder coating
3. It’s a bit of a diva when it comes to maintenance; if you want it to last a long time, it will need regular tending to
4. It’s not exactly what you would call a lightweight metal

What is Aluminum?

Aluminum is another type of metal that’s found in abundance in the earth’s crust (meaning it’s pretty easy to get hold of), though it’s found in the state of metal salts like bauxite, which is a rock deposit that’s rich in aluminum oxide. Aluminum is lightweight when it’s made into its final metallic form. Here’s an example of what it looks like:

What is Aluminum?

Aluminum is another type of metal that’s found in abundance in the earth’s crust (meaning it’s pretty easy to get hold of), though it’s found in the state of metal salts like bauxite, which is a rock deposit that’s rich in aluminum oxide.

Aluminum is very versatile, and so is found pretty much everywhere—from cars, trucks, airplanes, ships, PC bodies, cans, and high-voltage conductors to body panels, wheels (alloyed with magnesium), frames, windows, doors, and roofs, to name a few. Xometry customers use this aluminum thanks to its many perks, including low density, high strength-to-weight ratio, corrosion resistance, and thermal conductivity. 

What Does Aluminum Look Like?

Aluminum is a silver-white metal that generally has a matte finish. Figure 2 shows an example of processed aluminum:

What Is Aluminum Used For?

Aluminum is a versatile and widely used metal with a vast array of applications. Its unique combination of properties makes it suitable for many industrial, structural, and product applications. For example, in the transportation sector, aluminum is extensively used in the manufacturing of cars, trucks, airplanes, trains, and even ships. It is used in engine components, body panels, wheels (alloyed with magnesium), and frames. Aluminum is also commonly utilized in the construction industry. Its corrosion resistance, strength, and durability make it a popular choice for building structures, including: roofs, windows, doors, and facades.

What Are Examples of Aluminum?

Aluminum has extensive application across various industries. Some examples of aluminum parts are listed below:

1. Extruded aluminum alloys are used for window and door framing. 
2. Deep-drawn aluminum sheets allow beverage and aerosol cans to be made cost-effectively. 
3. Long-distance and high-voltage conductors rely on aluminum as it has a considerably lower cost than copper for almost the same performance. 
4. Apple and other computer manufacturers use die cast and machined aluminum for PC bodies as it is lightweight and durable.

What Are the Advantages of Aluminum?

Aluminum offers a range of advantages that contribute to its widespread use in most areas of product and human environments. These are:

1. It has a low density and high strength-to-weight ratio, so it’s perfect for situations that require less weight but good performance, like transportation
2. It naturally resists corrosion by forming an oxide layer on its surface when exposed to air
3. It’s a very good heat and electricity conductor (around 60% of the electrical conductivity and 50% of the thermal conductivity of copper, at a fraction of the raw material cost)
4. It’s ductile, malleable, and somewhat weldable
5. It’s highly recyclable, and it actually requires less energy to recycle than it does to make

What Are the Disadvantages of Aluminum?

Aluminum has many advantages, but there are also application and performance difficulties that must be accounted for:
It’s more expensive than steel (its main alternative) because it requires a lot of energy to produce

1. Its thermal conductivity could be a disadvantage in situations where you don’t want temperature distortion and unnecessary thermal transfer
2. It can become brittle and lose some of its structural strength and durability when exposed to sudden temperature changes or extremely high temperatures
3. Compared to other metals, it has a low melting point which can become an issue in high-temperature applications
4. Although it’s more corrosion-resistant than many other metals, it can still corrode in some environments

What Are the Applications of Galvanized Steel and Aluminum?

Many applications can be made from either galvanized steel or aluminum, and both metals have specific properties that make them suitable for certain uses. Galvanized steel is a popular choice for applications that require a durable, rust-resistant material. For example, it is commonly used in the construction of automobiles, roofing, and fences. Walkways and stair surfaces are commonly made from aluminum or galvanized steel treadplate, each of which has particular application advantages.

Aluminum benefits from having a low density and high strength-to-weight ratio, making it particularly useful in transportation industries for structures such as: aircraft, some ships, and railway cars. Low weight can benefit the making of: building components, electrical equipment, and cooking utensils.
Both galvanized steel and aluminum are used extensively in the manufacturing of fan blades. Galvanized aluminum sheet materials are more specifically used in this application due to their lightweight property. However, most HVAC (heating, ventilation, and air conditioning) ducting and fan enclosures are made in galvanized steel sheets for their low cost of materials and high processability.

How To Choose Between Galvanized Steel and Aluminum?

Choosing between these two metals will first require a comprehensive comparison of their properties (don’t worry; we’ve got one below for you). What it will come down to in the end are your exact needs and budget. Sometimes these materials can be used for the same thing, such as walkways, stairs, and fan blades, but most times you’ll find that one will be better than the other at making a particular item. For example, galvanized steel is stronger and more durabile, but it certainly can’t beat aluminum when it comes to light weight and strength-to-weight ratio.

What Is the Weight of Galvanized Steel?

The weight of a galvanized steel component depends primarily on the steel alloy. In general, the weight variation wrought by the zinc coating is negligible compared with the steel substrate beneath. The density of galvanized steel can vary slightly depending on the specific alloy but it is typically around 0.284 pounds per cubic inch (7.85 grams per cubic centimeter) or 7,850 kilograms per cubic meter.

Which Is More Malleable, Galvanized Steel or Aluminum?

Aluminum has a high malleability, which means it can be easily bent, shaped, or formed into various configurations without losing its structural integrity. Galvanized steel is also malleable to a certain extent, but less so than aluminum.

For applications that require extensive shaping, forming, or intricate designs, aluminum is often the easier-to-process choice. However, extreme forming of steel can be performed hot, allowing for increased complexity of shape as a consequence of accepting the increased complexity of the process.

How Do Galvanized Steel and Aluminum Differ in Thermal Conductivity?

Aluminum thermal conductivity is generally between 205–220 W/m·K, while galvanized steel typically has a thermal conductivity of about 50–60 W/m·K.

How Much Does Galvanized Steel and Aluminum Cost?

The cost of galvanized steel and aluminum varies widely depending on various factors, including: the type, form, thickness, size, and market conditions.

The cost of galvanized steel can range from $0.50 to $1.50 per pound, depending on the specific grade and form. Aluminum prices can range from $1.50 to $3.00 or more per pound for common aluminum alloys, influenced by grade, form, and market conditions.

For accurate pricing information, it's necessary to contact metal suppliers to get an accurate application/volume-specific price for your needs.

Which Is More Durable, Galvanized Steel or Aluminum?

The relative durability of galvanized steel and aluminum depends heavily on the application and environmental factors.

Galvanized steel is renowned for its durability, particularly in outdoor and (mildly) corrosive environments. It is often used in applications in which long-term durability is a key driver. However, galvanized steel will corrode if the zinc coating is compromised or if it is exposed to unsuitable conditions. Overall, galvanized steel benefits from the properties of steel—toughness, ductility, high tensile strength, low fatigue rates, and hardness—with the zinc coating compensating for the high environmental susceptibility.

Aluminum is naturally corrosion-resistant due to the formation of a self-healing protective oxide layer on its surface, making it moderately damage-tolerant in terms of corrosion resilience. Aluminum is lightweight making it a suitable choice for applications in which weight and corrosion resistance are essential, such as in: aerospace, marine, and outdoor applications. However, it may not be as strong or durable as galvanized steel in some heavy-duty or high-impact applications. In particular, aluminum is more susceptible to fatigue failures and can become embrittled by stress and temperature fluctuations.

Is Galvanized Steel More Rust-Resistant Than Aluminum?

Yes, galvanized steel is generally more rust-resistant than aluminum in most non-aggressive environments. The zinc coating on galvanized steel serves as a sacrificial barrier. When it gets scratched or damaged, the surrounding zinc corrodes before the underlying steel, providing a measure of ongoing protection.

Aluminum naturally forms a thin oxide layer on its surface, which protects it from corrosion. While aluminum is highly corrosion-resistant and does not rust in the same way that steel does, it can still corrode in certain specific environments, such as highly acidic or alkaline conditions and in places where mineral deposits can collect.

In typical outdoor environments, in which exposure to moisture is common, galvanized steel's rust resistance tends to be superior to the resistance of aluminum to corrosion, but both will perform well and survive long term. The cost then drives the selection of galvanized steel for applications like: fencing, structural components, and outdoor equipment.

In marine environments, aluminum offers some benefit in corrosion performance over galvanized steel, as long-term salt exposure will affect steel considerably more than the self-healing oxide barrier on aluminum, once the zinc begins to erode.

Can Aluminum Be Welded?

Yes, aluminum can be welded by various methods. In all cases, the selection of an appropriate filler material (where a filler is used) can affect weld appearance and strength. In particular, control of heat input is critical for good welding results, as excess heat combined with aluminum’s excellent thermal conductivity can cause excessive heat-affected zone (HAZ) development and extensive melting.

Can Aluminum Be Galvanized?

Yes, the hot-dip zinc plating (or electroplating) of aluminum is commonly performed. In general, this is done to enable the zinc to act as a sacrificial anode in the electrochemical process of corrosion, improving the life span of parts and preserving the aesthetic appearance for a longer duration.

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