How is Steel Made? A Deep Dive into the Composition of Steel and Stainless Steel

Posted on August 01, 2025 at 05:01 PM

Steel is the silent giant of our civilization. It forms the skeletons of our cities, the bodies of our vehicles, and the tools in our hands. Yet, for a material so integral to our lives, many questions remain. What is it made of? How is it produced? And what is the real difference in the steel vs stainless steel debate?

As leaders in the steel industry, Amardeep Steel is here to provide clear answers. This guide will walk you through everything you need to know about this essential alloy.

The History of Steel Manufacturing

Iron was mined by mankind for almost 5000 years before steel was invented. The game-changer came in the 5th century B.C.E. when Indian craftspeople melted iron and mixed it with charcoal. Iron and charcoal melted to answer the question: what is steel made of? Steel is an iron-carbon alloy that is stronger than iron. Knowing this simple composition of steel laid the path for changes, no one could proceed past slow, small-scale steelmaking for generations.

The Industrial Revolution would bring even significant modifications to the steelmaking process. The 1850s saw a revolution in steel production, regardless of how it was created. In the 1850s, the Bessemer process produced vast amounts of steel by forcing air into molten iron to make it purer but lesser quality. The Open-Hearth technique extended melting time to control steel quality and produce superior steel.

Alloy steels changed modern steelmaking in the 20th century. All other metals are raw. By adding chromium or nickel to the steel-making process to enhance corrosion resistance, steel might become exceedingly hard.

What Is Steel Made Of?

Steel is primarily an alloy of iron and carbon, with other elements like manganese, silicon, phosphorus, and sulfur present in varying amounts depending on the desired properties. The composition of steel is carefully controlled during manufacturing to produce grades suitable for structural, mechanical, and industrial use.

Key Raw Materials in Steel Production

The main materials involved in making steel are:

Iron Ore – The main source of iron in the alloy
Coke or Coal – Acts as both a fuel and a reducing agent to turn iron ore into molten iron
Limestone – Functions as a flux, helping to eliminate impurities by forming slag

Steel Manufacturing Techniques: How Is Steel Made?

There are three principal processes used in steelmaking today, each tailored to specific use cases and production needs.

Basic Oxygen Steelmaking (BOS)
Also known as the Linz-Donawitz process, Basic Oxygen Steelmaking is one of the most common modern methods. It starts with molten iron produced in a blast furnace. This molten iron is transferred to a converter, where a jet of pure oxygen is blown through it. The oxygen reacts with impurities like carbon, silicon, and manganese, oxidizing them and separating them out as gas or slag. The result is high-quality steel with controlled chemical characteristics.
Electric Arc Furnace (EAF)
The Electric Arc Furnace method is generally preferred for production of steel as a method to utilize scrap material. By melting scrap steel, the Electric Arc Furnace melts recycled steel by dissolving scrap steel with electrical energy from the arcs of carbon electrodes. In the process of steelmaking, Electric Arc Furnaces allow for a more sustainable and cleaner way of producing steel by recycling; additionally, Electric Arc Furnaces enable steelmakers to make adjustments in the composition of steel by adding specific alloying elements as opposed to relying on melting the right mix of scrap materials.
Open Hearth Process (Historic)
Once widely used in the later 19th and early 20th Century, the Open Hearth Method has been all but used extinct. This method, developed by Siemens and Martin, blended pig iron, scrap, and flux in a rather large reverberatory furnace; although slow, it allowed for large batches to be processed while maintaining a degree of control of refinement process. Unlike the oxygen converter and Electric Arc Furnace projects and while slower, it did a better job of allowing steelmakers to make adjustments in the mix of materials. However, the method was soon replaced by the oxygen converter and Electric Arc Furnaces; by the 1990's, the Open Hearth Method saw little growth and was on par with calmer methods of producing steel in terms of decarbonization and environmental footprint.

Steel Production Workflow: From Ore to Final Product

This is the starting point in the production process, where raw materials are converted into crude steel. Both the BOS and EAF methods fall under primary steelmaking and form the backbone of modern steel production.

Primary Steelmaking

Creating steel involves several phases, from raw materials to the final rolled or formed product.

Secondary Steelmaking

Once crude steel is made, it is refined further to achieve the required steel composition. Secondary processes like:

Ladle Furnace (LF) treatment – where additional elements are added or removed
Vacuum Oxygen Decarburization (VOD) – used to lower carbon levels and control impurities

These steps fine-tune the final properties of the steel to match different industrial specifications.

Casting

The refined molten steel is then cast into intermediate forms like ingots, billets, or blooms. Casting can be done in two ways:

Ingot Casting – pouring into molds for traditional shaping
Continuous Casting – more efficient and widely used today for uniformity

Rolling and Forming

In the final stages, the steel is rolled into flat products like plates, coils, or strips, or formed into structural components using processes such as:

Hot Rolling or Cold Rolling
Forging
Extrusion or Stamping

This stage defines the steel's final geometry and mechanical behavior depending on where and how it will be used.

An Overview of Steel Types and Their Properties

Steel encompasses a wide range of types, each with distinct characteristics tailored for specific applications. The most common is Carbon Steel, an affordable alloy of iron and carbon known for its strength. Alloy Steel enhances this base by adding elements like chromium or nickel to improve properties such as heat or corrosion resistance. A prominent example is Stainless Steel, which includes chromium for superior corrosion resistance.

Other specialized types include Tool Steel, which is formulated to endure high temperatures, and Weathering Steel, which forms a protective rust-like layer for weather resistance without needing paint. Finally, Structural Steel is a broad category used in construction, valued for its load-bearing strength and versatility.

Carbon Steel

Carbon steel is a widely used material in construction, automotive, and manufacturing as a very versatile material whose properties are defined by the amount of carbon in steel classified as either low, medium, or high levels.

Low-Carbon Steel: low-carbon steel is often called mild steel which has a low percentage of carbon (under 0.30%) and aspects like weldability, ductility and simple fabrication make it a popular choice due to its quality in design, and because the relatively low percentage of carbon in the mild steel when compared to its alloyed cousins, is not as strong as them but will form well, heavily used in the automotive body parts, furniture, general purpose machinery as well as many other products.
Medium-Carbon Steel: medium-carbon steel is characterized as having a carbon content between 0.30% and 0.60%. Medium-carbon steel offers a good balance between strength, ductility and toughness and exploiting through heat treatment if hardness is required. Medium-carbons steel is best to use for parts that have moderate strength and wear from workability stresses such as gears, axels, crankshafts, etc.
High-Carbon Steel: high-carbon steel has a carbon content normally over 0.60% possessing exceptional hardness, tensile strength and wear resistance but more brittle than other types of carbon based steels. High-carbon steel is good for cut edges and knives and heavy duty spring manufacturing.

Alloy Steel

Alloy steel is created by adding specific elements to the base iron-carbon mixture to achieve enhanced properties. Common alloying elements include chromium (for hardness and corrosion resistance), nickel (for toughness), manganese (for strength and wear resistance), and tungsten (for hardness at high temperatures).

Low-Alloy Steel: This type contains a small percentage of alloying elements. It offers improved strength and toughness over carbon steel without sacrificing too much ductility, making it useful for structural parts and automotive components.
High-Alloy Steel: Containing a significant amount of alloying elements (often over 10%), this steel exhibits exceptional properties like extreme strength, heat resistance, and corrosion resistance. It is used in demanding environments for components like aerospace parts and turbine blades.

Stainless Steel

Stainless steel is a type of alloy steel renowned for its signature resistance to corrosion and its aesthetic appeal. The stainless steel composition, primarily iron and a minimum of 10.5% chromium, creates a passive oxide layer on the surface that protects it from rust. This makes it valuable in industries from food processing to medicine. Different grades are suited for different uses

Austenitic: The most common type, it has high levels of chromium and nickel, providing excellent corrosion resistance and formability. It's used for kitchenware, medical equipment, and architectural details.
Ferritic: With high chromium and little to no nickel, this magnetic steel has good corrosion and heat resistance. It is often used for automotive exhaust systems and appliances.
Martensitic: Known for its high carbon content, this grade is heat-treated to achieve extreme hardness and strength, making it ideal for cutlery, surgical tools, and industrial blades.
Duplex: A combination of austenitic and ferritic structures, this steel offers both high strength and excellent corrosion resistance. It is used in chemical processing, marine, and oil and gas applications.
Precipitation-Hardening (PH): This specialized steel achieves its superior strength and toughness through a specific heat treatment process. It is used in harsh environments for aerospace parts and drilling equipment.

Other Major Steel Categories

Tool Steel: A category of steel engineered for its high hardness and wear resistance, allowing it to hold a cutting edge and maintain its shape under heat and pressure. It is used to make cutting tools, molds, and dies.
Weathering Steel (COR-TEN): This unique steel is designed to form a stable, rust-like patina when exposed to the atmosphere. This layer protects the steel from further corrosion, eliminating the need for paint and making it a low-maintenance choice for outdoor bridges and sculptures.
Structural Steel: This refers to steel designed for construction. Its exceptional strength-to-weight ratio allows for the creation of robust yet lightweight building frameworks. It is easily fabricated and is a key component in efficient, modern construction.

What is Stainless Steel Made Of? A Guide to Stainless Steel Composition

So, what is stainless steel made of to give it that signature, rust-proof shine? The secret lies in its unique stainless steel composition.

The defining element is chromium (Cr). To be classified as stainless, the steel must contain a minimum of 10.5% chromium. This element creates a thin, passive, and self-repairing oxide layer on the surface that protects the iron from rust and corrosion.

The stainless steel composition is often enhanced with other elements for superior performance:

Nickel (Ni): Improves toughness, stability, and formability.
Molybdenum (Mo): Provides superior corrosion resistance, especially against chlorides found in marine and chemical environments.

Explore our full range of stainless steel products to find the ideal material for your application.

Steel vs Stainless Steel: Which is Right for Your Project?

One of the most common decisions in material selection is the steel vs stainless steel debate. Choosing the right one is critical for your project's longevity and performance.

Corrosion Resistance: This is the primary difference. Stainless steel is inherently resistant to rust. Carbon steel must be painted or coated for protection.
Cost: The addition of valuable alloys like chromium and nickel makes stainless steel more expensive than carbon steel.
Strength: Both materials are incredibly strong, but different grades excel in different ways. Certain high-carbon steels can be harder, while many stainless steels offer a better combination of strength and ductility.
Appearance: Stainless steel provides a modern, clean finish, while carbon steel has a matte appearance and is typically used where aesthetics are less of a concern.

Ultimately, the choice in the steel vs stainless steel comparison comes down to your application's environment, budget, and required physical properties.

Key Applications of Steel Across Industries

Steel is certainly versatile and strong, it is also durable and an essential part of the modern world. Steel drives the future for production across all industries. Consider the following uses of steel and how they push operations forward.

Construction: Steel is the foundation of modern construction and accounts for over 50% of global demand. Structural steel makes up the beams and columns of buildings, while rebar strengthens concrete. Deposit stainless steel to create aesthetic facades.
Automotive: High strength steels are used to manufacture automotive frames and body to obtain strength while also minimizing weight and maximizing fuel economy and safety.
Aerospace: High-strength, heat resistant, steel alloys are essential to produce aircraft frames and bodies, landing gear and engine components. In aerospace, steel must withstand extreme stress during operation.
Energy: Steel is the primary material for any type of energy component. Steel is used to build the structure of oil and gas pipelines, wind turbines and power generation plants. All energy components are used in strange environments for operations. Steel is the material of choice for structural integrity and reliability.
Medical Equipment: Stainless steel surgical instruments, implants and hospital equipment provide corrosion resistance and sterilization.
Shipping & Marine: The ability of steel to resist saltwater corrosion, the bulk of weight steel ships breakwater vessels, steel is the industry standard for everything from cargo ships to yachts.
Consumer Goods: Stainless steel has become the benchmark for kitchen appliances and cutlery, while common framework materials for furniture are steel. Steel is part of life!

The Advantages of Using Steel

The Benefits of Steel

Exceptional Strength: Steel's strength-to-weight ratio allows it to support heavy loads and span long distances without bending. Thus, it is often the material of choice for heavy construction and heavy machinery.
Superior Durability: Steel will not rot, warp nor crack like two other common construction materials, wood and concrete. When correctly wet and maintained, steel maintains its integrity for decades, resulting in an extremely serviceable life and lower maintenance costs in the long run.
Recyclable Infinite: Steel is iconic for the environment because it can be recycled endlessly without any degradation of quality. Furthermore, the recycling process conserves natural resources and generates substantially less energy than creating new steel, thereby reducing carbon fixation.
Value for Money: Steel is seen as having a high initial cost and is extremely cost-effective over time. Its durability produces fewer repairs, its available for pre-fabrication and is more efficient to ship, which ultimately reduces labor and shipping costs.

Partner with the Experts at Amardeep Steel

Whether your project requires the foundational strength of carbon steel or the lasting durability of stainless steel, understanding the material is key. At Amardeep Steel, we don't just supply steel; we provide solutions.

Contact us today for a quote, and let our team of experts help you select the perfect, high-quality material to ensure your project's success.