Steel is an iron and carbon alloy that is stronger and more fracture-resistant than other types of iron. Due to its great tensile strength and inexpensive cost, steel is one of the most frequently created materials in the world.
Buildings, bridges, infrastructure, tools, automobiles, trains, bikes, machinery, electrical appliances, furniture, and weaponry are all made of steel, as well as concrete reinforcing rods and other building materials.
Steel always has iron as the primary component, yet it can also include or be enriched with many other elements. The corrosion and oxidation resistance of stainless steel usually requires an extra 11% of chromium.
In this reading, we will delve into the definition of steel, its composition, and its manufacturing process. We’ll also explore the advantages and disadvantages of steel in their various applications.
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Related: What is Stainless Steel? Its Properties, Types & How it is Made
What is Steel?
Iron is produced by removing oxygen and other impurities from iron ore. Iron, carbon, recycled steel, and trace elements make steel. Steel is an iron-carbon alloy with trace silicon, phosphorus, sulfur, oxygen, and less than 2% carbon and 1% manganese.
Steel leads building and engineering globally. Our cars, building materials, washing machines, refrigerators, cargo ships, and healthcare scalpels include it.
Iron is steel’s basis. It crystallizes into body-centered cubic or face-centered cubic allotropic forms depending on temperature. The way iron allotropes interact with alloying elements, particularly carbon, gives steel and cast iron unique properties.
Pure iron is soft and easily produced because its crystal structure allows iron atoms to move past each other. Small quantities of carbon, other elements, and iron inclusions harden steel to prevent dislocations.
Applications
Steel is widely used today across various industries for wide variety of applications. below are the uses of steel:
- Automotive
- Construction
- Infrastructure
- Energy and Power
- Manufacturing & Machinery
- Shipbuilding
- Aerospace
- Consumer Goods
- Defence
- Medical & Healthcare
- Electronics
- Domestic Appliances
Related: The Various Types of Stainless Steel Finishes and Their Applications
What are the Properties of Steel?
The properties of steel include strength, hardness, ductility, toughness, corrosion resistance, thermal conductivity, electrical conductivity, weldability, magnetic properties, and recyclability.
1. Ductility:
Steel is easily built or shaped without breaking because of its ductility. This characteristic makes a variety of production techniques possible, including bending, forging, and rolling.
2. Toughness:
Steel is able to absorb energy and sustain impact without breaking, indicating that the material has strong toughness. The safety and dependability of steel constructions are enhanced by this characteristic.
3. Thermal Conductivity:
Steel can transport heat well because of its comparatively high thermal conductivity. Applications like heat exchangers and cooking utensils benefit from this feature.
4. Electrical Conductivity:
Steel nevertheless has electrical conductivity, even if it isn’t as conductive as copper or aluminum. This property makes steel helpful in situations that need for electrical conductivity or grounding.
5. Corrosion Resistance:
The presence of alloying metals like chromium gives certain forms of steel, notably stainless steel, excellent resistance to corrosion. Steel is able to withstand corrosion and deterioration in corrosive environments and damp conditions because of its features.
6. Strength:
Steel is well known for its exceptional strength, which offers superior load-bearing capability and structural integrity. Its strength makes it possible to build sturdy, long-lasting buildings.
7. Hardness:
By alloying it or applying heat treatment, steel can become harder, increasing its resistance to abrasion, wear, and deformation.
8. Recyclability:
Steel is very recyclable, which contributes to its sustainability and friendliness to the environment. Its qualities allow for recycling and reuse without sacrificing it, which lowers the need for raw materials and energy usage.
9. Weldability:
Steel’s excellent weldability makes it possible to join steel components together effectively using various welding techniques. This feature simplifies the assembly and manufacturing of steel structures.
10. Magnetic properties:
Steel may exhibit magnetic characteristics depending on its manufacturing and processing methods. Electrical transformers and motors employ special kinds of steel, such as electrical steel, because of its magnetic properties.
Related: 13 Different Types of Steel and Their Uses
Physical Properties of Steel
The Table below Shows the Physical Properties of Steel:
| Properties | Typical Value Range | Unit | Examples |
| Hardness | 40 – 70 HRC | Rockwell hardness scale | D2 Tool Steel, 4140 Alloy Steel |
| Tensile Strength | 370 – 2,070 MPa | Megapascals | 304 Stainless Steel, 4340 Alloy Steel |
| Thermal Conductivity | 15 – 50 W/m·K | Watts per meter·Kelvin | Carbon Steel, 316 Stainless Steel |
| Thermal Expansion | 10.8 – 13.5 µm/m·K | Micrometers per meter·Kelvin | Medium Carbon Steel, Alloy Steel |
| Young’s Modulus | 190 – 210 GPa | Gigapascals | Low Carbon Steel, Tool Steel |
| Melting Point | 1,370 – 1,540°C | Degrees Celsius | High Carbon Steel, Stainless Steel |
| Density | 7,700 – 8,050 kg/m³ | Kilograms per cubic meter | Carbon Steel, Alloy Steel |
| Crystal Structure | Face-centered cubic (FCC) or body-centered cubic (BCC) | N/A | Carbon Steel, Stainless Steel |
Chemical Properties of Steel
The Table below Shows the Chemical Properties of steel.
| Steel Type | Corrosion Resistance | Oxidation | Reactivity | Magnetism | Stability |
| Carbon Steel | Moderate to low | Prone | Reacts with certain chemicals | Non-magnetic | Stable |
| Stainless Steel | High | Resistant | Resists chemical reactions | Non-magnetic (some types can be slightly magnetic) | Stable |
| Alloy Steel | Varies based on alloying elements | Varies based on alloying elements | Varies based on alloying elements | Varies based on alloying elements | Varies based on alloying elements |
Related: What is Cast Iron? its Applications, Properties, & Types
What are the Types of Steel?
Below are the list of the various types of steel:
1. Carbon Steel
2. Stainless Steel
3. Alloy Steel
4. Tool Steel
5. High-Strength Low-Alloy (HSLA) Steel
6. Electrical Steel
7. Weathering Steel
8. Galvanized Steel
9. Maraging Steel
10. Dual-Phase Steel
11. Electrical Transmission and Distribution Steel
12. Spring Steel
13. Nitriding Steel
Material Used in Steelmaking
Carbon, which typically contributes up to 2%, and iron, the base metal, make up the majority of steel. Steel contains smaller amounts of other elements, such as silicon, phosphorus, sulfur, oxygen, chromium, and manganese.
These additional elements may be included deliberately to change the properties of the steel, such as strengthening it, increasing its durability against corrosion, or simplifying specific production processes.
Because iron and carbon are combined, as well as these alloying elements are present in controlled amounts, steel has a unique range of mechanical and chemical properties. Because of this, steel is a flexible material used in a wide range of industries.
How Do We Make Steel?
Steelmaking is the process of producing steel through a series of stages. The most used method is the basic oxygen furnace (BOF) process, which involves melting iron ore in a blast furnace to produce pig iron.
Thereafter, excess carbon and impurities are blown out of the molten iron using a high-pressure oxygen jet in a basic oxygen furnace to refine the pig iron. At this stage, the necessary composition and qualities can be obtained by adding other components like manganese, chromium, or nickel.
Another technique that uses recovered steel waste as the primary raw material for pig iron is the electric arc furnace (EAF) process. An electric arc formed between electrodes melts the scrap metal in the EAF. Thereafter, the scrap metal undergoes further purification with the addition of other alloys and suitable chemical modifications.
After the steelmaking process, the molten steel is formed into billets, slabs, or blooms. It may undergo additional processing procedures such as rolling, forging, or heat treatment to further enhance its properties before being used in a range of applications.
Related: How Steel Is Produced? 6 Steps Of Steel Manufacturing Process
How to Heat Treat Steel
In the metal industry, heat treatment plays a crucial role as it heats steel beyond its austenite transition point to martensite.
This procedure increases steel brittleness, strength, and form retention. Hardening, annealing, normalizing, tempering, and case hardening are heat treatments.
Hardening a metal increases its hardness and strength by heating and cooling it quickly. However, annealing reduces internal tensions, making metal more ductile and improving grain structures. Normalizing ferrous metal relieves internal strains and strengthens it.
Tempering lowers internal tensions and brittleness, improving steel toughness.
Depending on the alloy and application, the procedure involves heating steel below the lower critical temperature and above it. It generates soft or rigid metal depending on the cooling rate. Controlled heat makes high-speed steel.
Advantages of Steel
The following explains the benefits of steel in their various applications:
Steel is a versatile material known for its exceptional strength and durability, with high tensile strength and resistance to bending, cracking, and deformation. It can be shaped, welded, and formed into various shapes, allowing for customization and flexibility in design.
Stainless steel, a type of steel, exhibits excellent corrosion resistance due to its chromium content, which prevents rust and corrosion. Steel is also considered a sustainable material, being 100% recyclable, reducing the need for raw materials and energy consumption.
Its elevated melting point guarantees both fire protection and structural integrity in structural applications.
Steel is cost-effective, offering a balance between cost and performance, with low maintenance requirements and long-term cost savings. Its thermal conductivity allows for efficient heat transfer, making it suitable for applications like heat exchangers, cookware, and heating systems.
Lastly, steel’s aesthetic appeal, with its sleek, modern appearance, is often desired in architectural and design applications.
Disadvantages of Steel
The following explains the limitations of steel in their various applications:
Steel grades, including stainless steel, have varying levels of corrosion resistance, requiring proper maintenance and protective coatings. Steel is a dense material, making it heavy and potentially prone to fatigue, which can lead to structural failure.
Brittle fractures can occur under certain conditions, especially at low temperatures, causing sudden failure without significant deformation or warning signs.
Steel production also has a significant environmental impact, with greenhouse gas emissions and the extraction of raw materials.
Although steel is recyclable, the recycling process still requires energy and resources.
Additionally, steel’s high conductivity may not be desirable in applications like electrical transmission lines or thermal bridges, necessitating additional insulation or measures to mitigate heat transfer.
Therefore, while stainless steel is a desirable material, other steel grades may require alternative materials for applications requiring weight reduction.
Related: What is Iron (FE)? its Properties, Types & Raw Materials
FAQs
What Is Steel?
Compared to other kinds of iron, steel, an alloy of iron and carbon, has superior strength and fracture resistance. It could also include other elements including silicon, manganese, and chromium.
What Is Steel Made of?
Iron, which acts as the base metal, and carbon, with a normal carbon content that ranges up to 2 percent, make up the majority of steel. Smaller quantities of a wide range of other elements, like silicon, phosphorus, sulfur, oxygen, chromium, and manganese, are present in steel.
How Is Steel Made?
Steelmaking, a series of steps, often produces steel. The most often used technique is the basic process of a basic oxygen furnace (BOF).
What Color Is the Steel?
Usually, steel has a silvery or metallic gray color. It’s important to remember, though, that various elements, like surface polish, coatings, and lighting, can affect how steel looks.
What Does Steel Look Like?
Steel usually has a gray or silver color and a metallic element. Its surface is reflective and smooth, particularly after polishing or other treatment. The surface finish, coatings, treatments, and other manufacturing processes may all affect how steel is textured.
What Types of Steel?
The different types of steel are carbon steel, alloy steel, stainless steel, electrical steel, galvanized steel, maraging steel, tool steel, HSLA steel, weathering steel, dual-phase steel, electrical transmission and distribution steel, spring steel, and nitriding steel.
What Are the Properties of Steel?
The properties of steel include strength, hardness, ductility, toughness, corrosion resistance, thermal conductivity, electrical conductivity, weldability, magnetic properties, and recyclability.