The steps in the galvanizing process are as follows:
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What are the advantages of galvanized steel?
Many different industries utilize galvanized steel primarily because it has such a wide array of benefits for industries to take advantage of, including having:
Low initial cost compared to most treated steels. In addition, galvanized steel is immediately ready to use when delivered. It does not require additional preparation of the surface, inspections, painting/coatings, etc. sparing companies more costs on their end.
Longer life. With galvanization, a piece of industrial steel is expected to last more than 50 years in average environments, and can last over 20 years with severe water exposure. There is no maintenance required. The increased durability of the steel’s finished product also increases the product’s reliability.
The sacrificial anode ensures that any damaged steel is protected by the surrounding zinc coating. It doesn’t matter if the steel section is completely exposed; the zinc will still corrode first. The coating will corrode preferentially to the steel, creating a sacrificial protection to the areas that are damaged.
Rust resistance from the zinc coating. The iron elements in steel are incredibly prone to rusting, but the addition of zinc acts as a protective buffer between the steel and any moisture or oxygen. Galvanized steel is very protective, including sharp corners and recesses that couldn’t be protected with other coatings, making it resistant to damage.
Different methods of galvanizing
As stated above, there are several different processes for galvanizing steel.
Hot-Dip Galvanizing
The first and foremost method for galvanization is hot-dip galvanizing. The process is very similar to what the name suggests! In this method, steel or iron is dipped in a molten pool of zinc that maintains a temperature of around 860°F (460 °C). This molten bath begins a metallurgical bond between the zinc and the receiving metal. After the metal is pulled from the bath, it reacts to being exposed to the atmosphere, and the pure zinc mixes with oxygen to form zinc oxide. The zinc-oxide further reacts to carbon dioxide and forms zinc carbonate, which makes up the final protective coating on the material. The tell-tale sign of a hot-dipped galvanized material is the presence of a crystalline-like pattern on the surface, sometimes referred to as “spangle.”
The hot-dipped galvanizing method is an economical choice that can be quickly executed on both simple and complex shapes.
The new coated material can be worked and machined in a similar fashion to uncoated materials. Galvanized steel can be used in high-temperature applications up to 392 °F, but use in temperatures exceeding that level will cause the zinc-carbonate layer to peel off.
Galvannealing
Galvannealing is the outcome of combining the annealing and hot-dip galvanizing processes in order to produce a specialized coating on steel. The process of galvanization is performed via hot-dipping and instantaneous annealing, which produces a matte gray finish.
Galvannealed steel is a zinc-iron alloy product, where the base metal is coated by the hot-dip process, then heated to induce alloying between the molten zinc coating and the steel. The resulting finish is a dull matte surface. Galvannealed steel is conducive to welding and the surface is excellent for paint adhesion.
Pre-galvanizing
Also similar to the hot-dip galvanizing method, but performed at the very first stage of production. Pre-galvanizing is a process that involves rolling the sheet metal through a cleaning agent to quickly prime material for galvanizing. Then, the metal is passed through a pool of molten liquid zinc and is immediately recoiled. The primary advantage of this method is that coils of steel sheet can be rapidly galvanized on a large scale with a more unified coating than the traditional hot-dipped method.
Electrogalvanizing
The most unique of these outlined methods, electrogalvanizing does not involve dipping the material in a molten vat of zinc. Instead, an electric current is introduced to an electrolyte solution that is applied to the steel, which reduces positively charged zinc ions to zinc metal – which is then deposited on the positively charged steel. Like pre-galvanizing, this method is typically done at the first stage of production.
Galvanizing advanced high-strength steel
For more information about the galvanization process for advanced high-strength steel, as well as our partner National Galvanizing, please click here.
What industries utilize galvanized steel?
Galvanized metals are used everywhere!
The bodies of cars and many bicycles are made from galvanized metals. Some drinking water pipes are still made from galvanized steel. Cool rolled sheet metal is also frequently galvanized. Nuts, bolts, tools, and wires of all kinds are now galvanized because it is a cheap process, and helps boost the metal’s lifespan!
Galvanized steel, in particular, is often what is used in modern “steel frame” buildings. Galvanized steel is also used to create structures like balconies, verandahs, staircases, ladders, walkways, and more. Galvanized metal is the ideal choice if your project will live outside after it’s done. Fences, roofs, outdoor walkways, these are all great choices for galvanized metal!
Well, there you have it! With our partner Heidtman Steel, National Galvanizing runs a 245,000-square-foot facility, featuring pickling, galvanizing, galvannealing, and slitting, all in one location, convenient to major markets. This combination of capabilities provides our customers with unparalleled responsiveness to meet the ever-changing demands of today’s market.
Galvanization is a process designed to help steel resist corrosion and provide protection to keep it looking and performing great.
However, these are all key traits of stainless steel as well.
So which is better for your next project?
In this guide, we’ll compare stainless steel and galvanized steel across a variety of common considerations and use types to help highlight the strengths and weaknesses of these two popular steel variations.
Before we can compare them, it’s essential to understand how galvanized steel is made.
Essentially, galvanized steel is simply zinc-plated steel.
There are multiple ways to galvanize steel parts and components, but they all provide similar results as long as they are correctly performed.
The most common method of galvanizing steel is hot-dipping.
In this process, standard steel is dipped in molten zinc, creating a layer of zinc that bonds with the surface of the steel, providing protective benefits and an appealing appearance.
Electro-dipping and thermal diffusion methods are also used when parts are particularly small or complex.
This layer of zinc serves the same purpose as the passive layer of chromium oxide on the surface of stainless steel, helping the metal resist corrosion and repel scuffs, dings, and other minor physical abuses.
This also means that you end up with a layered finished product instead of a fully alloyed product like stainless steel.
In general, no.
However, this will depend on the specific situations in which you plan to use your galvanized or stainless steel parts.
Galvanized steel offers excellent resistance against water and chlorine but pales in comparison to stainless steel’s corrosion resistance when dealing with marine environments.
The protective layer on galvanized is also not self-healing like the passive layer on stainless steel.
This means that over extended periods, galvanized parts are generally less durable than stainless ones.
However, even if the zinc layer on a galvanized component is damaged, it will still serve as a sacrificial cell in galvanic corrosion processes, encouraging rust formation on the damaged zinc areas instead of the underlying steel.
In general, stainless will offer better corrosion resistance and offer it for a longer period as well.
When compared at similar thicknesses and forms, stainless steel is always stronger than galvanized steel.
An effective way to compare this is by looking at the tensile strength of each material.
Tensile strength is the resistance of a material to breaking under tension.
Exact figures will vary by the alloy in use.
The tensile strength of stainless steel alloys typically starts around 515 megapascals (MPa) and can reach as high as megapascals (MPa) in some cases.
Structural steel has a tensile strength of 400 megapascals (MPa), while carbon steel has a tensile strength of 841 megapascals (MPa).
Both are commonly used for creating galvanized steel productions.
Since galvanization does not impact the tensile strength of the underlying metal, you could reasonably expect galvanized steels made from various steel grades to have comparable tensile strength compared to the original steel.
In most cases, stainless steel and galvanized steel will have a very similar weight.
The specific differences will vary depending on the exact stainless steel alloys in question and the zinc coating thickness on the galvanized steel product.
More alloyed metals or a thicker coating will result in greater weight. This is unavoidable.
Galvanized steel offers the same malleability as the underlying steel used.
This means that in most cases, it will be more malleable than comparably shaped stainless steel forms.
If you must use stainless steel and want greater malleability but aren’t sure how to pick the perfect stainless steel grade, consider austenitic grades.
These contain higher amounts of nickel, making them more formable for larger objects like sinks, basins, and tanks.
Both stainless steel and galvanized steel should conduct heat in a relatively similar manner.
However, in the case of galvanized steel, you must keep the melting temperature of zinc in mind.
While molten zinc is non-toxic, heating galvanized steel past zinc’s melting point could create burn or fire hazards as the zinc coating liquefies and separates from the underlying steel.
On a structural level, both types of steel should provide excellent heat tolerances for use in high heat areas.
Both stainless steel and galvanized steel are weldable. However, both feature unique considerations.
Welding stainless steel can degrade the passive layer and create brittleness.
This can lead to reduced corrosion resistance or compromise the structural integrity of the stainless steel parts in question.
Pickling treatments can help to reduce the impact of welding and heat exposure in most stainless applications.
For more information, please visit Galvanized Steel Sheet.
You must adequately capture or ventilate welding fumes with galvanized steel as zinc oxide fumes can be harmful when inhaled.
If welding near stainless steel, you must also be sure to keep any molten zinc created away from the stainless components.
Failure to do so can result in embrittlement of any affected stainless.
For these reasons, it’s recommended to perform welding before galvanizing whenever possible.
This answer will entirely depend on the family of steel used.
For galvanized steel, if the steel which was covered in zinc was magnetic, the zinc coating should not interfere with the magnetic response.
If you’re intentionally looking for (or want to avoid) magnetic steel options, austenitic steels are the most magnetic.
Other alloys will exhibit various levels of magnetism based on their iron content.
Both metals will offer safe, effective use in most foodservice environments.
Galvanized steel is an extremely popular option for building shelving for walk-in coolers.
It also provides a unique appearance for serving platters and other decorative elements.
However, you must take care to avoid highly acidic foods around galvanized steel as they can degrade the zinc layer surprisingly fast with regular exposure.
Stainless steel is less reactive, so if you’re looking for a more versatile option, it’s your best bet.
Galvanized steel is also not as smooth as many stainless steel finishes and gets coarser over time.
This means that clean-up requirements will increase over time along with the change in surface texture.
Related Guide: Stainless Steel Use in the Food Service Industry
In almost all cases, stainless steel will win out over galvanized steel in the medical environment.
Medical uses, such as equipment, tools, or even implants, require long-lasting performance and easy to clean surfaces.
Whether you’re talking about scalpels or surgical theatre surfaces, you’re likely to see stainless in use nearly everywhere.
Galvanized steel’s coarse surface and the ability for the zinc coating to scratch or chip make it less safe for medical use and potentially more challenging to clean.
Related Guide: Effective Stainless Steel Usage in Medical Environments
While exact price differences depend on market conditions, stainless steel will almost always cost more than galvanized steel.
Affordability is one of the biggest reasons to choose galvanized steel over stainless steel.
When long-term use isn’t critical, or the components won’t see frequent use or abuse, galvanized offers a solid alternative to stainless in many ways.
Both metals are recyclable.
However, galvanized steel is often turned into more standard steel, which must go through the galvanization process again.
Recycling stainless steel is more straightforward, simply going from solid to molten and back again with monitoring and adjustments to address any impurities or alter the alloy in desired ways.
Stainless steel’s versatility, durability, and easy cleaning and maintenance make it ideal for many uses.
However, common industries where you might find stainless in action regularly include:
Aerospace
Agriculture
Architectural
Automotive
Construction
Electronics
Foodservice
Heating
Home appliances
Manufacturing
Marine
Medical
Oil and gas
Pharmaceutical
Power generation
Pulp and paper
Sports equipment
Often viewed as an affordable alternative to stainless steel, galvanized steel sees regular use in a variety of industries, including but not limited to:
Agricultural
Automotive
Construction
Foodservice
Heating and Air
Manufacturing
Power generation
Telecommunications
In most cases, you’ll see that industries use both metals, taking advantage of the strengths of each while avoiding apparent weaknesses.
Ultimately, as with most metal choices, stainless steel or galvanized steel isn’t automatically best for everything.
Some differences will make them more or less suited for various uses.
The outstanding corrosion resistance, easy maintenance, and superior strength of stainless steel make it an ideal choice in a vast range of situations.
However, if the strength and corrosion resistance aren’t required, you’ll likely pay more for stainless steel components than galvanized ones.
So when it comes to efficiency, it pays to research your needs thoroughly.
If you’re not sure where to start, consider these points:
Stainless steel is almost always more robust than galvanized steel. So if structural elements are involved, stainless will likely be a better bet.
Stainless steel provides stronger corrosion resistance than galvanized steel -- especially in marine environments.
While both stainless steel and galvanized steel will offer comparable heat tolerances in terms of structural strength, you must take care to avoid melting the zinc coating on galvanized steel parts and components.
Welding stainless steel is safer and more accessible than welding galvanized steel as zinc oxide fumes can create hazardous conditions, and molten zinc can damage nearby stainless components.
Galvanized steel is often more malleable than stainless steel, though this will depend on the exact grades of steel used.
Galvanized steel is almost always lower priced than stainless steel. When cost is the most critical factor, galvanized steel is the way to go. If service life is the biggest concern, stainless will likely outperform galvanized over the longer term.
As one of Canada’s leading suppliers of stainless steel parts, components, and materials, Unified Alloys combines an extensive range of products with more than four decades of experience to ensure your needs are met at every stage of the buying process. Contact one of our expert sales analysts today to discuss options and highlight ways we can help supply your next project!
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