Angle steel is a widely used structural steel product with an L-shaped cross-section, commonly used in construction, machinery manufacturing, steel structures, and infrastructure projects. Depending on surface treatment, angle steel can be classified into ordinary (black) angle steel and galvanized angle steel.
The main difference between galvanized angle steel and ordinary angle steel lies in their surface protection and corrosion resistance. Galvanized angle steel is coated with a layer of zinc through hot-dip galvanizing or electro-galvanizing processes, which significantly improves its resistance to rust and environmental corrosion. Ordinary angle steel, on the other hand, has no protective coating and therefore requires additional painting or coating if used in outdoor or humid environments.
Understanding the differences between these two types of angle steel is important for selecting the appropriate material for structural, industrial, and engineering applications.
What Is Ordinary Angle Steel?
Ordinary angle steel, also known as black angle steel or carbon steel angle, is produced directly from hot-rolled carbon steel without additional surface treatment.
Key Characteristics
Natural steel surface without protective coating
Lower cost compared with galvanized angle steel
Requires painting or anti-rust treatment for outdoor use
Suitable for indoor structures or protected environments
Common Standards
Ordinary angle steel is typically produced according to standards such as:
ASTM A36
EN 10056
GB/T 9787
JIS G3192
Typical Applications
Structural frameworks
Machinery manufacturing
Equipment supports
Indoor steel structures
What Is Galvanized Angle Steel?
Galvanized angle steel is angle steel that has been coated with a layer of zinc to protect the steel from corrosion. The most common method is hot-dip galvanizing, where the steel is immersed in molten zinc to form a durable protective layer.
Key Characteristics
Zinc coating provides excellent corrosion resistance
Longer service life in outdoor environments
Reduced maintenance and repainting costs
Suitable for humid, marine, and industrial environments
Zinc Coating Thickness
Hot-dip galvanized angle steel typically has zinc coating thickness ranging from:
45 – 275 g/m²
This coating acts as a protective barrier and provides sacrificial corrosion protection.
Typical Applications
Outdoor construction structures
Power transmission towers
Highway guardrails
Solar mounting systems
Agricultural structures
Key Differences Between Galvanized Angle Steel and Ordinary Angle Steel
| Feature | Galvanized Angle Steel | Ordinary Angle Steel |
|---|
| Surface Treatment | Zinc coated | No coating |
| Corrosion Resistance | Excellent | Low |
| Maintenance | Minimal | Requires painting |
| Cost | Higher | Lower |
| Service Life | Long | Shorter in outdoor environments |
| Typical Use | Outdoor and corrosive environments | Indoor structures |
Manufacturing Process Differences
Ordinary Angle Steel Production
Steel billet heating
Hot rolling into angle shape
Cooling and straightening
Cutting to length
Galvanized Angle Steel Production
Production of ordinary angle steel
Surface cleaning and pickling
Flux treatment
Hot-dip galvanizing
Cooling and inspection
The galvanizing process forms a metallurgical bond between zinc and steel, providing durable corrosion protection.
Advantages of Galvanized Angle Steel
Superior Corrosion Protection
The zinc layer protects the steel from moisture, chemicals, and atmospheric corrosion.
Longer Service Life
Galvanized steel structures can last 20–50 years depending on environmental conditions.
Reduced Maintenance Costs
Unlike painted steel, galvanized steel rarely requires repainting or maintenance.
Strong Structural Performance
The galvanizing process does not significantly affect the mechanical strength of the steel.
How to Choose Between Galvanized and Ordinary Angle Steel
When selecting the appropriate angle steel type, consider the following factors:
Use galvanized angle steel when:
The structure is exposed to outdoor environments
There is high humidity or corrosive atmosphere
Long-term durability is required
Use ordinary angle steel when:
The structure is located indoors
Budget is a primary concern
Additional surface coatings will be applied later
Typical Sizes of Angle Steel
| Size | Thickness | Weight (kg/m) |
|---|---|---|
| 25 × 25 mm | 3 mm | 1.12 |
| 40 × 40 mm | 4 mm | 2.42 |
| 50 × 50 mm | 5 mm | 3.77 |
| 75 × 75 mm | 6 mm | 6.85 |
| 100 × 100 mm | 8 mm | 12.2 |
Both galvanized and ordinary angle steel are available in these standard structural sizes.
The characteristics are different
-
Low treatment cost: the cost of hot-dip galvanizing and rust prevention is lower than that of other paint coatings
-
Durable: hot-dip galvanized angle steel has the characteristics of surface luster, uniform zinc layer, no leakage plating, no dripping, strong adhesion, corrosion resistance and so on. In the suburban environment, the standard hot-dip galvanized anti-rust layer can be maintained for more than 50 years without repair; In urban or offshore areas, the standard hot-dip galvanized anti-rust layer can be maintained for 20 years without repair
-
Good reliability
The galvanized layer is metallurgically combined with the steel and becomes a part of the steel surface, so the durability of the coating is more reliable.
Characteristics of ordinary angle steel
The surface quality of the angle steel is specified in the standard, and the general requirements are that there shall be no harmful defects in use, such as delamination, scarring, cracks, etc.
The allowable range of geometric deviation of angle steel is also specified in the standard, which generally includes bending, side width, side thickness, top angle, theoretical weight and other items, and the angle steel should not have obvious torsion.
Different uses
► Galvanized angle steel use: widely used in power towers, communication towers, curtain wall materials, shelf construction, railway, highway protection, street lamp poles, marine components, building steel structure components, substation ancillary facilities, light industry, etc.
► Ordinary angle steel use: mainly used for metal components and the frame of the workshop. In use, it is required to have good weldability, plastic deformation performance and certain mechanical strength.
Hot-dip galvanized angles
Hot-dip galvanized angle steel is also called hot-dip galvanized angle steel or hot-dip galvanized angle steel. It is to immerse the derusted angle steel in the molten zinc melted at about 500 °C, so that the zinc layer is attached to the surface of the angle steel, so as to play the purpose of anti-corrosion, and is suitable for various strong acid, alkali mist and other strong corrosive environments.
The thickness of the galvanized layer of hot-dip galvanized angle steel is uniform, up to 30-50um, with good reliability, and the galvanized layer is metallurgically combined with the steel and becomes a part of the steel surface, so the durability of the coating of hot-dip galvanized angle steel is more reliable.
Cold galvanized angles
The cold galvanizing process is used to protect the metal from corrosion, for which a zinc-filler coating is used, which is applied to the protected surface by any coating method, and after drying, a zinc-filler coating is formed, which has a zinc content (up to 95%) in the dry coating.
Suitable for repair work (i.e., during repair work, only where the protected steel surface is damaged, the surface can be re-applied as long as the surface is repaired). The cold galvanizing process is used for the corrosion protection of various steel products and structures.
merit
Low treatment cost: the cost of hot-dip galvanizing and rust prevention is lower than that of other paint coatings;
Durable: hot-dip galvanized angle steel has the characteristics of surface luster, uniform zinc layer, no leakage plating, no dripping, strong adhesion and strong corrosion resistance, and the standard hot-dip galvanized anti-rust thickness can be maintained for more than 50 years without repairing in the suburban environment; In urban areas or offshore areas, the standard hot-dip galvanized anti-rust layer can be maintained for 20 years without repair
Good reliability: the galvanized layer and the steel are metallurgically combined and become a part of the steel surface, so the durability of the plating layer is more reliable;
Strong toughness of the plating: the galvanized layer forms a special metallurgical structure, which can withstand mechanical damage during transportation and use;
Comprehensive protection: every part of the plated parts can be zinc-plated, even in the depressions, sharp corners and hidden places can be fully protected;
Time-saving and labor-saving: The galvanizing process is faster than other coating construction methods, and can avoid the time required for painting on the construction site after installation.
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FAQ
What is galvanized angle steel?
Galvanized angle steel is carbon steel angle that has been coated with a protective zinc layer through a galvanizing process, usually hot-dip galvanizing. The zinc coating protects the steel from corrosion and significantly extends its service life in outdoor environments.
What is ordinary angle steel?
Ordinary angle steel, also known as black angle steel, is hot-rolled carbon steel angle without any surface coating. It is commonly used in indoor structures or applications where additional surface protection such as paint will be applied.
What is the main difference between galvanized and ordinary angle steel?
The main difference is the surface treatment. Galvanized angle steel has a zinc coating that provides corrosion resistance, while ordinary angle steel has no protective layer and is more prone to rust when exposed to moisture.
Is galvanized angle steel stronger than ordinary angle steel?
No. The mechanical strength of galvanized and ordinary angle steel is generally the same because they are usually produced from the same carbon steel grades. The galvanizing process mainly improves corrosion resistance rather than structural strength.
Why is galvanized angle steel more expensive?
Galvanized angle steel costs more because it undergoes an additional galvanizing process, which involves cleaning, pickling, fluxing, and coating the steel with molten zinc. This extra processing increases production cost but also improves durability.
Can ordinary angle steel be galvanized after fabrication?
Yes. Ordinary angle steel can be galvanized after fabrication through hot-dip galvanizing, which is often used for structural components that require corrosion protection after manufacturing.
What industries commonly use galvanized angle steel?
Galvanized angle steel is widely used in:
Construction and infrastructure projects
Power transmission towers
Solar mounting structures
Highway guardrails
Agricultural buildings
Outdoor steel frameworks
Where is ordinary angle steel typically used?
Ordinary angle steel is commonly used in:
Indoor steel structures
Machinery frames
Equipment supports
Structural fabrication in controlled environments
What is the typical zinc coating thickness for galvanized angle steel?
Hot-dip galvanized angle steel usually has a zinc coating thickness ranging from 45 g/m² to 275 g/m², depending on the galvanizing standard and application requirements.
How long does galvanized angle steel last?
In normal atmospheric conditions, hot-dip galvanized angle steel can last 20 to 50 years without significant corrosion, depending on environmental exposure.
Can galvanized angle steel be welded?
Yes, galvanized angle steel can be welded. However, the zinc coating near the weld area may be affected and usually requires post-weld treatment or recoating to maintain corrosion protection.
Which type of angle steel should be used for outdoor structures?
For outdoor structures exposed to rain, humidity, or corrosive environments, galvanized angle steel is generally recommended because of its superior corrosion resistance and longer service life.
