What is Steel? Applications of Steel in Our Life

Steel is a crucial industry for economic and social development. Not only is steel highly applicable and pervasive in daily life, but it is also a valuable resource symbolizing technological and scientific advancement in nations, especially developing ones.

The development of the steel industry drives the industrialization of a country, thereby addressing employment needs for a significant labor force and supporting the growth of related industries.

However, not everyone understands this industry well. MaTec Vietnam will provide you with important information about steel and the steel industry to help you better understand this key sector and its impact on the mechanical processing industry.

What is Steel?

Steel is an alloy primarily composed of iron (Fe), melted with carbon (C) and several other chemical elements (Si, Mn, P, S, Cr, Ni, Mo, Mg, Cu, etc.). The chemical elements in the steel alloy and their concentrations play a role in adjusting the hardness, elasticity, ductility, oxidation resistance, and strength of the steel. Due to this diversity, there are over 3,000 types of steel worldwide.



Chemical Properties of Steel

Steel is a metallic material, so it has a metallic luster, and is highly conductive of electricity and heat. At temperatures between 500°C and 600°C, steel becomes ductile and its strength decreases. At -10°C, its ductility decreases. At -45°C, steel becomes brittle and prone to cracking.

Steel possesses high overall mechanical properties, good formability, and comes in many types with various uses, making it a highly versatile material. It is widely used in industries such as construction, mechanical manufacturing, and shipbuilding.

Properties Of Steel

In the steelmaking process, varying the ratio of carbon to iron can create a wide range of steel structures with different properties. Thus, steelmaking does not produce a single uniform product; the type of steel produced depends on the needs and intended use.

The carbon content in steel is no more than 2.14% by weight.

Higher carbon content results in harder and stronger steel, but it becomes more brittle and prone to breaking, making it less malleable. Conversely, lower carbon content increases ductility.

What is Carbon Steel?

Carbon steel primarily consists of iron and carbon, with other elements present in very small, almost negligible amounts.

Despite having only two main elements, carbon steel can be produced in numerous ways with various applications by adjusting the carbon content, depending on its intended use.

Based on carbon content:

  • Low carbon steel: carbon content ≤ 0.25%
  • Medium carbon steel: carbon content 0.25% – 0.6%
  • High carbon steel: carbon content 0.6% – 2%


What is Structural Carbon Steel? 

This group of steel has higher quality than regular quality steel, reflected in its lower content of harmful impurities (S ≤ 0.04%, P ≤ 0.035%), precise carbon content, and clearly defined mechanical properties. 

Structural carbon steel is detailed in guides that list both composition and mechanical properties. It is used in manufacturing high-stress machine parts such as gears, worms, cams, and springs.

According to Vietnamese standards (TCVN), structural carbon steel is designated by the letter C, followed by a number indicating the carbon content. For example, C20, C45, C65, etc.

Example: C45, where C denotes carbon steel, and 45 indicates 0.45% carbon content.

International Designations:

  • Japan (JIS): Designated as SxxC, where xx indicates the carbon content percentage. For example, S45C has 0.45% carbon.
  • USA (AISI/SAE): Designated as 10xx, where xx indicates the carbon content percentage. For example, 1045 has 0.45% carbon.


What is CT3 Steel?

CT3 steel is a type of low carbon structural steel in group C, with a tensile strength rating of 8. It is primarily used in the manufacturing of machine parts, molds, and metal plates, and has many applications in construction, steel structures, ports, metalworking, and machinery components.

CT stands for low carbon, and 3 indicates that it is a structural steel in group C. According to the TCVN 1765 – 75 standard for steel grades, group C includes designations like CCT34, CCT38, etc. The numbers following 3 (specifically 4, 8) indicate the steel’s tensile strength.

What is Tool Carbon Steel?

Tool carbon steel is a type of steel with high carbon content (0.7 – 1.4%) and low levels of impurities such as sulfur (S) and phosphorus (P) (< 0.025%). Although tool carbon steel has high hardness when heat-treated, it has low heat resistance, making it suitable for use in tools like chisels, files, measuring instruments, and various stamping dies.

According to Vietnamese standards (TCVN), tool carbon steel is designated by the letters CD, followed by a number indicating the carbon content per ten thousand, such as CD70, CD80, CD100.

Example: CD100 – where CD stands for tool carbon steel, and 100 indicates 1% average carbon content.

What is Alloy Steel?

Alloy steel contains, in addition to the two main elements, a combination of other elements ranging from 1% to 50% to alter the mechanical properties of the product.

Based on the total content of additional metal elements, alloy steel is classified into:

  • Low alloy steel: total content of other metal elements ≤ 2.5%
  • Medium alloy steel: total content of other metal elements 2.5% – 10%
  • High alloy steel: total content of other metal elements > 10%

In construction and domestic applications, low alloy steel is commonly used. Low alloy steel typically includes elements such as manganese, chromium, silicon, nickel, etc., in amounts not exceeding 10%. Each alloy element added to steel has a different function:

  • Chromium (Cr): The main component in creating stainless steel, with a chromium content ranging from 10.5% to 26%.
  • Nickel (Ni): Enhances the strength and toughness of the steel.
  • Manganese (Mn): Added to steel to deoxidize during melting, preventing the formation of iron sulfide impurities that can cause steel to crack. Manganese content is only 0.5% to 0.8%.
  • Silicon (Si) and Copper (Cu): Added in small amounts to resist sulfuric acid (H2SO4) corrosion.
  • Nitrogen (N): Increases the strength of the steel.
  • Molybdenum (Mo): Added to prevent pitting and cracking corrosion.
  • Sulfur (S): Improves machinability, but only a small amount is added to avoid sulfur brittleness.


What is Stainless Steel?

Stainless steel, also known as inox, is an iron alloy containing at least 10.5% chromium. Its most notable characteristic is its superior resistance to oxidation, making it less prone to discoloration or corrosion compared to other metals.

Chromium in stainless steel forms a protective oxide layer when exposed to air, known as chromium oxide. This very thin layer coats the material’s surface (often invisible to the naked eye).

The chromium oxide layer is inert to water and air, effectively protecting the underlying steel. This property makes stainless steel widely popular today, especially in household products.

There are four main types of stainless steel:

  • Austenitic
  • Ferritic
  • Austenitic-Ferritic (Duplex)
  • Martensitic


Types of Structural Steel Commonly Used

Structural steel refers to steel structures designed to bear loads. Each type of structural steel serves different functions and applications, necessitating informed selection based on specific needs.

  1. Plate Steel Plate steel is thin rolled steel (4-160 mm thick, 6-12 m long, 0.5-3.8 m wide), manufactured in sheet or coil form.
  2. H, I, U Shape Steel Shaped steel includes profiles like H, U, I, T sections, and steel tubes. These are formed through processes such as heat treatment (annealing, normalizing, quenching), hot mechanical processing (hot rolling, forging), and cold mechanical processing (cold rolling, drawing, forging).
    • Angle Steel: Also known as L or V steel, used in repairing machinery, main doors and windows corners, and as brackets.
    • U-shaped Steel: Widely used in workshops, truck bodies, and crane girders.
    • I-shaped Steel: Highly utilized in bridge construction, workshops, and mechanical engineering.
    • Thin U and I-shaped Steel: Various profiles used extensively in construction, shipbuilding, and automotive industries.
  3. Box Steel Box steel is formed from large steel (sheet metal) plates of customizable thicknesses, shaped into desired forms through molds. Types include square box steel and rectangular box steel.
  4. Hollow Round Steel (Steel Pipes) Hollow round steel pipes are hollow inside with relatively thin walls, offering high strength and flexibility. They are suitable for structures with bends.
  5. Sheet Steel (Coiled Steel) Coiled steel is a product rolled into smooth or ribbed coils, manufactured through a complex refining process requiring advanced technology. Hot rolled steel and cold rolled steel are its variants.
  6. Construction Steel (Solid Round Steel) Construction steel or solid round steel is processed into long cylindrical rods (12 m per rod), known for flexibility, bending resistance, and elongation capacity. It is commonly used in industrial or civil construction projects.
    • Plain Round Steel Bars: Smooth-surfaced, cylindrical bars typically 12 m long, with standard diameters like Ø14, Ø16, Ø18, Ø20, Ø22, Ø25 mm. They are supplied in bundles averaging 2000 kg/bundle and used in major construction pillars.
    • Ribbed Round Steel Bars: Also known as reinforced concrete steel bars with external ribs (grooves), commonly available in diameters like Ø10, Ø12, Ø14, Ø16, Ø18, Ø20, Ø22, Ø25, Ø28, Ø32 mm.
  7. Coiled Steel Bars Coiled or wire steel is a type of steel wire rolled into round coils, featuring smooth or ribbed surfaces with typical diameters of Ø6 mm, Ø8 mm, Ø10 mm, Ø12 mm, Ø14 mm. They are supplied in coils weighing approximately 200-459 kg/coil and used in wire drawing, construction, residential buildings, bridges, and tunnels.

>>> Read more: What Is the Difference between Titanium vs Stainless Steel?

Applications of Steel in Our Life

Today, steel has countless applications, making it indispensable in our daily lives.

In Construction 

The most significant application of steel in construction is its use as reinforced concrete. Incorporating steel enhances the durability and strength of buildings, ensuring their stability.

Furthermore, steel is utilized in constructing infrastructure and transportation projects to meet the needs of communities.

In Machinery Machining 

Steel finds extensive use in mechanical engineering for producing products such as corrosion-resistant flanges and machine components.

In the Shipbuilding Industry 

An indispensable application of steel is in the shipbuilding industry. Due to its high durability, heat and corrosion resistance, and ease of fabrication, steel is commonly used in ship construction. The hull, in particular, utilizes significant amounts of steel to prolong vessel lifespan.

Steel plays a crucial role across various sectors, contributing significantly to the reliability and advancement of modern infrastructure and technology.


Overall, MaTec Vietnam has helped you understand about steel, its classifications, and its applications in our daily lives. If you are seeking a manufacturer of parts and components using various types of steel with machines such as lathes and milling machines, MaTec Vietnam confidently presents itself as the perfect partner for you. 

With 10 years of experience in mechanical engineering, working with materials like stainless steel, steel plates, and round steel, we assure you of quality backed by ISO 9001:2015 certification. Contact us now for consultation and to receive the best price quote.

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