What is Galvanized Metal? Types, Process, and Benefits

Do you find yourself overwhelmed by the endless options for metal parts? You’re not alone. The suitable material can make or break your project, especially in industries where precision and durability are non-negotiable. So today, let’s dig into one game-changer material—galvanized metal.

Galvanized metal is a marvel in the metals industry. It’s essentially steel or iron coated with a layer of zinc, providing rust and corrosion resistance. Imagine having your cake and eating it too—that’s what galvanized metal offers: the durability of steel and the resistance of zinc.

Now, if you’re already intrigued, stick around. We’re about to unwrap the “metallic gift” that is galvanized metal, one layer at a time.

What is Galvanized Metal?

Definition of Galvanizing

Let’s cut through the jargon first. Galvanizing applies a protective zinc coating to iron or steel to prevent rusting. Think of it like a guardian angel for metals, always offering an added defense against the harsh elements. 

What is Galvanized Metal?

So, what exactly is galvanized metal? Simple. It’s an iron or steel object submersed in a zinc bath, resulting in a metallurgical bond between the zinc and steel or iron. This fusion creates a robust layer on the metal’s surface, making it resistant to corrosion and rust.

In lay terms, galvanized metal is like your everyday steel or iron but dressed to impress—durable, corrosion-resistant, and ready to tackle even the most challenging conditions. It’s the type of material that gives you peace of mind, and if you’re in any severe industry like aerospace or medical, you know how vital that is.

What Are the Types of Galvanized Metal?

You see, galvanization isn’t a one-size-fits-all deal. Different types cater to varying needs and applications. So, let’s roll up our sleeves and dissect each type, shall we?

Hot-Dip Galvanizing

Hot-Dip Galvanizing is the granddaddy of them all. In this method, steel or iron components are dunked into a vat of molten zinc. Imagine a metal baptism, if you will. This process creates a thick, durable layer perfect for heavy-duty applications. For those interested in technical specs, the zinc coating can range from 45 to well over 100 microns, depending on the dipping time. More info on this is available in here.

The zinc used in hot-dip galvanizing acts as a sacrificial anode. This means the zinc willingly gives itself up to corrosion, leaving the underlying metal untouched. It’s like the secret service of metals—ready to take a hit to protect what’s valuable.

Now, while hot-dip galvanizing offers robust protection, it can be more aesthetic. The finished surface can be rough, resembling an orange peel in texture. So, if you’re looking for beauty and brawn, consider other types.

Electro-Galvanizing

The technique uses an electrochemical process known as electrodeposition. During this process, the metal part that needs galvanizing acts as the cathode, while the zinc anode is dissolved into the solution. When an electrical current passes through the circuit, zinc ions move toward the metal part and adhere to its surface. The typical thickness of the zinc layer here is between 5 and 30 microns.

Electro-galvanizing produces a smooth and bright surface, making it the go-to option for visible components. Yes, this one’s for when you need your metal parts to shine, literally and metaphorically.

However, it’s important to note that while electro-galvanizing does offer corrosion resistance, it’s not as robust as hot-dip galvanizing. The thinner layer means less protection, but sometimes, less is more—especially when aesthetics are in play.

Mechanical Galvanizing

This process involves tumbling the metal parts in a drum along with zinc powder and glass beads. It’s like a rock tumbler but for metal, creating a coating typically between 25 and 75 microns thick. 

Mechanical galvanizing offers an exciting advantage: uniform coverage. Because there’s no dipping or electrical current involved, the zinc coating evenly covers even the most intricate shapes and crevices.

Yet, like all good things, mechanical galvanizing has its limitations. The process is better suited for smaller parts due to the tumbling action involved. So, while it might not be ideal for large-scale industrial components, it’s fantastic for those intricate, detailed pieces that require uniform protection.

Galvannealing

Galvannealing takes a page from both the hot-dip galvanizing and annealing processes. First, the metal is hot-dip galvanized, but instead of cooling it down immediately, it’s heated again in an annealing furnace. The result? A softer, more pliable zinc-iron alloy layer. For the technical minds out there, this specialized layer typically ranges from 8 to 12 microns. 

What sets galvannealing apart is its excellent paintability. The alloy layer serves as a stellar primer for paint, adhering much better than pure zinc. This makes it a choice for applications where aesthetics and additional coatings come into play.

However, it’s worth noting that while galvannealing does provide corrosion resistance, this resistance is generally lower than that offered by traditional hot-dip galvanizing. The zinc-iron alloy layer is less sacrificial than pure zinc, meaning it’s less willing to corrode to protect the underlying metal.

Pre-galvanizing

Pre-galvanizing, also known as mill galvanized or batch galvanized, involves galvanizing the metal sheet before it is cut and shaped. In essence, entire sheets or coils are galvanized in a controlled environment. Typical zinc thickness here varies between 50 to 70 microns.

The real selling point of pre-galvanizing is its uniformity. Because the sheet or coil is galvanized simultaneously, you get a smooth, even layer across the entire surface. It’s like spreading butter on a fresh slice of bread; every inch receives its fair share of protection.

The downside? Well, once you cut or shape the metal, the newly exposed edges won’t be galvanized. This could become a weak point where corrosion may initiate. So, while pre-galvanizing is convenient, there may be better choices for parts that require cutting or shaping post-galvanization.

Sherardizing

This unique process involves rotating the metal parts in a drum filled with zinc dust and heating the entire setup. The heating causes the zinc to bond with the metal, creating a zinc-iron alloy coating that typically ranges from 20 to 45 microns.

Sherardizing is particularly good for small, intricate parts with complex shapes, much like mechanical galvanizing. The heat and rotation ensure that the zinc dust reaches all the nooks and crannies, offering comprehensive protection.

But it’s not all roses and sunshine. The process of sherardizing is more time-consuming and, thus, tends to be more expensive. Plus, the resulting coating is a dull grey, which may be better if you want a more aesthetic finish.

How is the Galvanization Process Carried Out?

Well, even though each type of galvanization has its specific methods, some commonalities run through the entire galvanization realm.

Preparation

The metal to be galvanized must be impeccably clean. Think surgical-room level clean. It usually goes through a series of cleansing baths to remove any oil, grease, or existing oxides. Any trace impurities can sabotage the entire process, creating weak spots in the protective layer. Preparation is like the first impression; you get it wrong, and you’ll play catch-up for the rest of the relationship.

Galvanizing

Next, the real action begins. The cleaned metal is submerged in molten zinc or subjected to other galvanizing processes, depending on the type of galvanization. The temperature and timing need to be precisely controlled to ensure optimal adherence of zinc to the metal. It’s not as simple as “dip and done;” it’s a well-choreographed dance that balances numerous variables.

Now, how does zinc pull off this impressive feat of safeguarding the metal? The answer lies in the sacrificial nature of zinc. As I mentioned earlier, zinc acts as a sacrificial anode, willingly giving itself up to protect the underlying metal. In scientific terms, zinc has a more “negative electrochemical potential” than steel or iron. When both metals are exposed to an electrolyte (like water), the zinc will corrode first, sparing the metal underneath. Detailed insights can be found in this video.

But the zinc’s heroics don’t end there. When zinc corrodes, it forms zinc salts, which act as an additional barrier against corrosion. Think of it as a security system that gets tougher every time it’s breached. Moreover, in some galvanizing methods, zinc chemically bonds with the steel, creating a zinc-iron alloy layer that provides an extra level of durability.

In essence, the zinc doesn’t just act as a physical barrier and engages in some remarkable chemical wizardry to keep corrosion at bay. It’s like a multi-talented guardian that not only stands at the gate but also actively repairs the walls and fortifies the defenses.

Post-Galvanizing Surface Treatment

Once the metal is adequately coated, it doesn’t just march off the assembly line. No, sir. It undergoes a series of post-galvanizing surface treatments. These can range from quenching to passivation, each designed to improve the metal’s protective and aesthetic qualities. 

What Are the Key Benefits of Galvanized Metal?

Corrosion Resistance

First and foremost, the piece de resistance: corrosion resistance. We’ve already talked about the sacrificial nature of zinc and its willingness to corrode so your primary metal doesn’t have to. This results in superior corrosion resistance that keeps the elements at bay. It’s like having an elite bodyguard that takes the hit so you can keep going. 

Longevity

Galvanized metal is not a one-hit wonder; it’s in for the long haul. The longevity of a galvanized coating can range from a couple of decades to even a century, depending on environmental conditions and the thickness of the layer. Longevity equates to less frequent replacements and, therefore, reduced costs in the long term. 

Low Maintenance

With great longevity comes low maintenance. Unlike other coating systems like paint, which require regular touch-ups, galvanized metal is more of a “set it and forget it” material. This frees up time and resources for other aspects of the operation.

Cost-Effectiveness

In terms of bang for your buck, galvanized metal is a wise investment. Although the initial cost can be higher than some other types of protection, the long lifespan and low maintenance translate to cost savings over time.

Sustainability

For those with a green thumb, galvanized metal is your friend. Zinc is a natural, abundant element, and galvanized metal is entirely recyclable without losing properties.

Uniform Coverage

The galvanization process provides complete, uniform coverage, even on intricate shapes and hard-to-reach areas. This ensures that every nook and cranny is protected, leaving no weak spots where corrosion can creep in.

Quick Installation

Most galvanized products come ready to use, meaning there’s no need for additional preparations, like painting or inspections, before installation. This speeds up project timelines and allows for quicker turnarounds.

High Reliability

Consistency is vital in any industry, and galvanized metal delivers. Due to the rigorous quality control in the galvanization process, you can expect a highly reliable product, batch after batch.

Aesthetic Appeal

Galvanized metal has a shiny, aesthetic appeal that not only serves a functional purpose but also gives projects a clean, finished appearance.

What Metals Can Be Galvanized?

When it comes to galvanizing, not all metals are created equal.

Carbon steel is the star of the galvanizing show. It’s the most frequently galvanized material and for a good reason. Its natural predisposition to corrode is effectively mitigated by the zinc coating, making it an ideal candidate.

Following closely behind is cast iron. While less commonly galvanized than carbon steel, it still makes a worthy candidate. The galvanization process enhances its already favorable properties by providing an additional layer of corrosion resistance.

Some alloy steels can also be galvanized, but the presence of alloying elements like chromium and nickel can complicate the process. These alloying elements may result in uneven coating or reduced adherence of the zinc layer. So, it’s a tricky dance but doable under specific conditions.

Now, let’s clear up some misconceptions. Metals like aluminum, copper, brass, and stainless steel are generally not hot-dip galvanized using zinc. They have specialized methods for corrosion resistance, such as anodizing for aluminum and passivation for stainless steel.

So there you have it—carbon steel is your prime candidate for galvanization, with cast iron and some alloy steels also making the list. Other metals? Not so much. 

What Industries Commonly Use Galvanized Metals?

The construction industry is a massive consumer of galvanized steel. From the skeletons of skyscrapers to residential housing frameworks, galvanized steel provides the needed durability and corrosion resistance to withstand the elements.

Next up is the automotive industry. With a constant push for longevity and performance, galvanized metals frequently appear in car parts, body panels, and chassis to resist corrosion and increase the vehicle’s lifespan.

Ah, the backbone of modern civilization—roads, bridges, and public transport. These critical components rely heavily on galvanized metals for their corrosion resistance and structural integrity. The longevity of galvanized metals is a vital attribute in long-term infrastructure projects.

With the green wave hitting industries across the board, renewable energy setups like solar farms and wind turbines are jumping on the galvanized bandwagon. The corrosion resistance ensures that these installations last longer, even in harsh environmental conditions.

Yes, even farming has a stake in galvanized metals. From irrigation systems to machinery and fencing, galvanized materials are present to prolong life and reduce maintenance costs.

Last but not least is the marine industry. Given the corrosive nature of saltwater, galvanized metals are a no-brainer for applications like shipbuilding, harbor installations, and offshore drilling platforms.

Conclusion

If you’re in an industry where longevity and durability are more than buzzwords, it’s high time to consider integrating galvanized metals into your supply chain. Don’t be a stranger; contact us at Worthy Hardware for all your CNC machining needs, including top-notch galvanized parts. Because when it comes to metal, it’s not just about surviving—it’s about thriving.