Skip to content 
Steel structures are prone to rust and corrosion which can shorten their lifespan. Good news is that galvanized steel is the solution to this problem thanks to its protective coating. This guide will cover properties, types, benefits and uses of galvanized steel so you can protect your investments.
What is Galvanized Steel?
Galvanized steel is a type of steel which is coated with a layer of zinc to increase its corrosion and rust resistance. This zinc layer protects the steel surface from moisture and air in harsh or outdoor environments. You could recognize galvanized steel by its grayish color which has a spangled texture.
Galvanizing Steel Process
Galvanization has three stages: surface preparation, zinc immersion and post-treatment. First, the steel is cleaned with alkaline solutions and pickled in hydrochloric acid. Then it is immersed in molten zinc at 450 °C for 4-5 minutes where a zinc-iron alloy coating forms. Finally, steel is quenched in a chemical solution to get an additional layer of safety. This procedure gives a constant coating of zinc from 0.5 to 3.9 mils thickness.
Galvanized Steel Properties
Physical Properties
| Property | Rating | Value |
|---|---|---|
| Abrasion Resistance | Excellent | High |
| Density | Excellent | 7.8 g/cc |
| Rockwell Hardness | ExMedium | 74 B |
| Young’s Modulus | Excellent | 210 GPa |
| Tensile Strength | Excellent | 550 MPa |
Chemical Properties
| Element | Composition | Function |
|---|---|---|
| Zinc Layer | Fe-Zn alloy | Corrosion barrier |
| Phosphorus | < 0.05% | Coating adhesion |
| Carbonate Layer | ZnCO₃ | Environmental shield |
| Silicon | 0-0.04% or 0.15-0.25% | Coating formation |
| Base Steel Carbon | 0.25% or less | Core strength |
| Surface Oxide | ZnO + Zn(OH)₂ | Passive protection |
| Manganese | 1.3% or less than | Passive protection |
5 Major Types of Galvanized Steel
Galvanization produces several types of steel. Each is customized for particular industrial use. Let’s look at these types and their applications.
1. Hot-Dip Galvanized Steel
In hot-dip galvanizing, the steel is immersed in molten zinc. It forms zinc iron alloy layers on the surface of steel. This process is most suitable for industrial infrastructure, structural components, bridges, transmission towers and agriculture equipment where durability is important.
2. Electro-Galvanized Steel
Electro-galvanizing uses an electrochemical process. Basically, the steel becomes a cathode in a zinc sulfate solution. Now, electrolysis of this solution at room temperature deposits a very accurate zinc coating of 7-40 microns. This process produces spangle free surfaces which makes it appropriate for automotive panels and electronic casings that require outstanding surface finishes.
3. Galvannealed Steel
After initial hot-dip galvanizing, galvannealed steel undergoes additional heat treatment. The zinc coating is heated to 1050°F to produce a smooth matte finish. Manufacturers normally use galvannealed steel in HVAC systems, automotive panels and appliance production.
4. Pre-Galvanized Steel
Pre-galvanizing applies zinc coating to steel before its final shape. At the mill, the steel passes through a molten zinc bath and gets its protective layer before it is cut, bent or welded into components. Pre-galvanized steel is used in electrical conduits, furniture parts and HVAC ductwork.
5. Continuous Galvanized Steel
This type of steel is produced through a continuous hot-dip galvanizing process. Steel coils go through a molten zinc bath in a continuous automated line. High pressure air knives control the coating thickness with precision to create layers of 20 μm per side. This produces G90 class coatings with great formability for HVAC ductwork, automotive bodies and appliances.
Galvanized Steel Advantages
Galvanized steel is the top choice for many industrial applications because of its technical benefits.
- Galvanized steel is an outstanding value material for long term usage due to minimum maintenance, longer life and lower installation costs than alternative protective coatings.
- A steel surface with a galvanic coating of zinc can repair itself even if it gets corroded. Zinc coating also rusts at a slower rate than unprotected steel.
- In industrial applications, hot dip galvanized steel has amazing longevity. It can go over 70 years without maintenance due to the self healing properties of the zinc coating and the formation of a patina.
- One of the best things about galvanized steel is that it provides full surface coverage. The metallurgical bonding process assures even the hard to reach areas and sharp edges get protected.
- Galvanized steel uses natural zinc coating and generates minimum waste. Both zinc and steel are 100% recyclable.
What is Galvanized Steel Used for?
Galvanized steel is applied in a variety of industries. Its adaptability as well as strength makes it versatile for different purposes ranging from the use of large infrastructure to precision manufacturing.
Construction Industry
Galvanized steel is the main type of steel used for building purposes, i.e in structural components such as trusses, beams and columns. The material due to its weight bearing ability (up to 50,000 psi) and corrosion resistance is suitable for parking structures, multi-story buildings and bridges.
Automotive Industry
Vehicle manufacturers use galvanized steel in their designs. It’s a common material for chassis parts, body panels, underbody components and brake systems. Galvanized steel is also used to make bus infrastructure, oil filter tubes and license plate brackets. The material also decreases maintenance needs in these applications.
Agricultural Sector
Farmers and agricultural businesses use galvanized steel in livestock facilities, grain storage systems and irrigation equipment. The material resists harsh chemicals like pesticides and provides long term protection for greenhouse frames, storage silos, irrigation systems and components of heavy machinery.
Energy and Utilities
The energy sector uses galvanized steel in many ways. It’s an important component in transmission towers that support power lines, electrical substation frames and communication towers. Water supply systems, natural gas transportation, oil pipelines and sewage infrastructure also use galvanized steel for its strength and corrosion resistance.
Aerospace Industry
Galvanized steel is used in aircraft manufacturing. It’s used in ground support equipment, fuel tanks and airframe structures. The material protects corrosion prone parts such as landing gear, wing supports, fuselage panels, engine frames and auxiliary power units (APUs). This application provides long term rust resistance in aerospace components.
Manufacturing Industry
For heavy machinery’s structural parts like frames and housings, galvanized steel is broadly used as it needs very low maintenance. Besides that, it is also used in production lines like conveyor systems and tanks.
Considerations for Selecting the Right Galvanized Steel Type
In the process of identifying the suitable galvanized steel, there are many important technical characteristics that need to be taken into account. The following are most important:
Environmental Factors
The conditions of exposure will determine the type of galvanized steel. In marine, hot dip galvanized steel with a layer of over 3.9 mils is needed. On the contrary, electrogalvanized steel with 7-40 micron coating might be applicable in indoor applications. The best coating performance is usually achieved if the pH value is within the limits of 5.5 and 12.
Load-Bearing Capacity
Load bearing refers to the weight a material can hold without failing. For heavy duty applications like cranes, bridges and machinery, hot dip galvanized steel is appropriate. On the other side, a less strong galvanized steel type will suffice for lighter load bearing applications like shelving and storage racks.
Aesthetics
The surface characteristics and visual appearance of galvanized steel are aesthetic considerations. Hot dip galvanizing gives a natural matte grey finish with a uniform zinc patina. For custom aesthetics and extended life up to many decades, duplex systems combine galvanizing with paint or powder coating.
Regulatory Compliance
The choice of galvanized steel also depends on compliance requirements. Applications that require paintability and environmental sensitivity will benefit from galvannealed steel as it complies with the global regulations REACH and ISO 14963 in the automotive field and also sustainability projects.
Richconn – Galvanized Steel Fabrication Specialists
Richconn provides full galvanized steel fabrication services which include hot dip, electro galvanized and pre galvanized procedures. Our latest facilities have top of the line machines for precise fabrication of automotive parts, industrial equipment and structural components. We also guarantee strict quality control via CMM and X-ray inspection systems.
If you want to improve your project with galvanized steel? You can contact us today to speak with our experts and request a competitive quote.
FAQs
Does galvanized steel rust?
No. galvanized steel resists corrosion through sacrificial protection. The zinc coating over the base steel will be the one to corrode first, thus forming a protective film of rust that covers the base.
Can you weld galvanized steel?
You can weld galvanized steel but you have to take special precautions. Proper ventilation and removal of the zinc coating near the weld area are necessary. This produces zinc oxide fumes, so you need to follow particular safety protocols and welding techniques.
How long does galvanized steel last?
Hot-dip galvanized steel normally lasts a long time (70+ years) in industrial environments and 100+ years in rural areas with no maintenance. But this depends on coating thickness and environment.
Is galvanized steel conductive?
Yes, galvanized steel is conductive. It has an electrical conductivity of 1.611 × 10^-7 ohm-meters which is same as uncoated steel.
Galvanized steel vs stainless steel: What’s the difference?
Both are corrosion resistant but in different ways. Galvanized steel is a cost effective solution with the zinc coating. Whereas stainless steel is inherently corrosion resistant because of the chromium content.
Is galvanized steel magnetic?
Yes. The steel core still has a permeability of 100 and is thus magnetic. Whereas the zinc coating is non-magnetic. It makes it possible to use coating thickness testing.
Is galvanized steel sheet metal fabrication easy?
Fabricating galvanized steel sheet metal is relatively easy but requires expertise. The zinc coating requires special handling and tools to preserve the coating during cutting, forming and welding.
Is galvanized steel easy to machine?
Galvanized steel can be machined but not as easy as machining a bare steel. The zinc coating can cause tool wear and require modified cutting settings and adequate cooling during the machining.
