What Is Steel? Composition and Common Types of Construction Steel Today

In the construction industry, steel is always considered one of the core materials, playing a vital role in determining the strength, safety, and longevity of a structure. While steel is a familiar material, not everyone truly understands what steel is, its composition, or the different types of steel commonly used in construction today.

This article by Son Ha SSP will give you a comprehensive overview of construction steel.

1. What Is Steel?

Steel is an alloy primarily composed of iron (Fe) and carbon (C), with carbon content ranging from 0.02% to 2.14% by weight. The higher the carbon content, the harder the steel becomes, but at the expense of ductility.

In addition to iron and carbon, steel may also contain other elements such as manganese (Mn), silicon (Si), phosphorus (P), sulfur (S), or chromium (Cr), nickel (Ni), molybdenum (Mo)—depending on its intended use.

Steel Is An Alloy Primarily Composed Of Iron And Carbon

Why Steel Is an Irreplaceable Material in Construction and Manufacturing

One of the key reasons steel has become an irreplaceable material in construction and manufacturing lies in its outstanding properties. First and foremost, steel possesses high strength and ductility, enabling it to withstand significant impact forces without becoming brittle. At the same time, it can be bent or elongated to meet various technical requirements.

In addition, steel is easily processed through methods such as rolling, drawing, bending, and welding—allowing for a wide variety of shapes and product forms. Its applications go far beyond construction and extend to industries such as mechanical engineering, transportation, and heavy industry.

2. Basic Composition of Steel

The composition of steel directly determines its mechanical properties and suitability for different applications. The main elements include:

• Iron (Fe): The base element, making up the majority of the alloy.
  
• Carbon (C): The most crucial element, which influences the hardness and ductility of the steel.
  
  • Low-carbon steel (≤ 0.25% C): Ductile, easy to weld, commonly used in civil construction.
    
  • Medium-carbon steel (0.25–0.6% C): Stronger, often used for machine components.
    
  • High-carbon steel (≥ 0.6% C): Very hard, typically used for cutting tools. 
• Manganese (Mn): Increases hardness and wear resistance.
  
• Silicon (Si): Enhances strength and elasticity.
  
• Phosphorus (P) and Sulfur (S): Considered impurities; high levels can make steel brittle and prone to cracking.
  
• Other alloying elements (Cr, Ni, Mo, V, etc.): Improve corrosion resistance, heat resistance, or overall strength. 

Thanks to the varied combinations of these elements, steel properties can be customized for specific applications.

3. Common Types of Steel Used in Construction

In the construction sector, steel is classified based on shape, mechanical properties, and intended use. Below are the three most commonly used types:

3.1. Rebar (Reinforcing Steel Bars)

Rebar is long, rod-shaped steel used to reinforce concrete. Its surface can be smooth or ribbed with raised patterns, such as diagonal or parallel ribs.

• Plain round rebar: Smooth-surfaced, diameters from 6mm to 50mm. It is easy to bend and work with, and typically used in small structural components, ties, or secondary reinforcements.
  

Deformed (ribbed) rebar: Features raised ribs along its length to improve bonding with concrete. This is the most widely used type in housing, bridge, and infrastructure construction.

Steel Bars (Rebar)

Advantages of Steel Bars (Rebar)

• High tensile strength
  
• Excellent bonding with concrete, minimizing cracks and breakage
  
• Available in various sizes, making it easy to select according to the project’s needs 

Steel bars are typically bundled into batches, with total weights reaching up to approximately 3 tons, depending on the diameter and length of the bars.

Thanks to their outstanding mechanical properties, this type of steel plays a crucial role in load-bearing structures and is widely used in civil construction, industrial factories, transportation infrastructure, and high-rise buildings that demand exceptional structural integrity.

3.2. Steel Coils (Wire Rods)

Steel coil, also known as wire rod, is a type of steel in the form of long strands that are wound into large rolls for easy transportation and storage.

The common diameter of steel coil ranges from 6mm to 10mm, making it suitable for a wide variety of construction tasks.

Thanks to its high flexibility, ease of bending, and excellent workability, steel coil can be cut, drawn, or shaped into many different components.

Because of these advantages, steel coil is widely used in both residential and industrial construction projects, such as:

• Column ties
  
• Rebar ties
  
• Steel mesh production
  
• Fencing systems
  
• Light mechanical fabrication

Steel Coils (Wire Rods)

Advantages of Steel Coils (Wire Rods)

• Easy to transport and install
  

• Cost-effective
  

• Suitable for various types of residential and light industrial projects 

3.3. Steel Pipes

Steel pipes, also known as round hollow sections, are a type of steel with a hollow structure, featuring thin walls while still maintaining high strength and rigidity.

To enhance corrosion resistance and extend service life, the surface of steel pipes is often coated with protective layers such as paint, galvanization, or electroplating.

This type of steel is manufactured in a variety of shapes, including:

• Round pipes
  
• Square pipes
  
• Rectangular pipes
  
• Oval pipes
  

In terms of dimensions, steel pipes typically have:

• Wall thickness ranging from 0.7mm to 6.35mm
  
• Diameters starting from 12.7mm up to 219.1mm
  

Popular product categories include:

• Galvanized pipes
  
• Straight seam welded pipes
  
• Spiral welded pipes
  
• High-frequency welded pipes

Steel Pipes

Thanks to its durability, light weight, and ease of fabrication, steel pipes are widely applied across multiple industries.

In construction, they are commonly used in:

• Pre-engineered buildings
  
• Bored pile systems
  
• Load-bearing scaffolding
  
• Telecommunication towers
  
• Street lighting poles
  
• Drainage systems
  

Beyond construction, steel pipes are also utilized in mechanical manufacturing, including:

• Vehicle frames
  
• Automotive and motorcycle structures
  
• Oil and gas piping systems
  
• Interior and exterior decorative components 

Conclusion

We hope this article has provided you with a comprehensive overview of what steel is, its chemical composition, and the most common types of steel used in construction.

Clearly, steel is not just an ordinary material—it serves as the “backbone” of every structure, playing a vital role in ensuring long-term durability and safety.

When choosing steel, always prioritize standard-compliant products with clear origins from reputable brands. This ensures not only the quality of your project but also helps to optimize future maintenance and repair costs.

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