How Steel is Made, Step by Step

Chances are, you’ve already encountered steel in countless ways today – from the car you drove to work to the kitchen knife you used for lunch. Steel is everywhere, and life as we know it would be unrecognizable without it. Yet, most of us remain clueless about how this remarkable material is actually made.

Fear not! At Clickmetal, we’re here to demystify the process. Below, we’ll walk you through the step-by-step journey of how steel is crafted, starting from its raw materials and ending in the various forms it takes across industries.

Before We Begin...

Steel production is a complex process that can vary depending on the type of steel and the method used. While this guide focuses on the widely-used basic oxygen steelmaking technique, keep in mind that some steel is refined using electric arc furnaces or other methods. Now, let’s dive into how the standard process unfolds.

1. Gathering Raw Materials

The steel-making process kicks off by collecting essential raw materials: iron ore, coal, and limestone.

• Iron Ore: The primary source of iron, the key component in steel. Hematite and magnetite are among the most common types used.
• Coking Coal: This coal is transformed into coke, which generates the intense heat required to reduce iron ore into a usable form.
• Limestone: This acts as a flux, helping to remove impurities like silica, sulfur, and phosphorus during processing.

Other alloying elements, such as magnesium or nickel, may also be collected for later stages of refinement. These materials are mined from vast deposits and transported to steel mills, where the transformation into steel begins.

2. Turning Coal Into Coke

The next step involves converting coal into coke. This process takes place in a coke oven, where coal is heated in an oxygen-deprived environment. The result? Coke, a carbon-rich fuel that burns hotter and cleaner than regular coal. Coke is vital because it provides the immense heat needed in the blast furnace to melt the iron ore.

3. The Blast Furnace

With the coke prepared, the next phase is producing molten iron in a blast furnace—a towering structure that can reach heights of 100 to 200 feet. Here’s how it works:

• Iron ore, coke, and limestone are layered inside the furnace, which is lined with heat-resistant bricks.
• Extremely hot air, around 1,500–2,200°C, is blasted into the furnace from the bottom. This extreme heat ignites the coke, creating carbon monoxide gas that reacts with the iron ore, reducing it to molten iron.
• As the iron ore melts, impurities like silica form a liquid slag that floats on top of the molten iron. The purified iron, now in liquid form, sinks to the bottom of the furnace and is tapped off.

This molten iron, known as pig iron, still contains a high level of carbon and impurities, making it brittle. It requires further refinement to become steel.

Fun Fact: Pig iron earned its name due to the way the molds were arranged during casting. The molds resembled a mother pig with her piglets, with the larger mold for pouring the molten iron called the "sow," and the smaller ingots flowing from it called "pigs"!

4. Basic Oxygen Steelmaking (BOS)

The pig iron from the blast furnace is then transported to a basic oxygen furnace for refining into steel. This process reduces the carbon content and removes impurities, making the iron stronger and more versatile.

• Molten pig iron is poured into the furnace, and pure oxygen is blown in at high pressure. The oxygen reacts with the carbon in the pig iron, forming carbon dioxide and lowering the carbon content.
• Fluxes like limestone are added to help eliminate impurities. As the oxygen and fluxes interact with the carbon and other impurities, they form slag, which is removed.
• The amount of oxygen injected and the timing of the process are carefully adjusted to achieve the desired carbon level for the specific type of steel being produced (e.g., 0.3% for mild steel) while maintaining the steel’s essential properties.
• At this stage, alloying elements like manganese, chromium, or nickel can be added to impart specific characteristics, such as enhanced strength or corrosion resistance. This results in different types of steel, with stainless steel being one of the most famous examples.

The outcome is high-quality liquid steel with significantly reduced carbon levels compared to the initial pig iron.

5. Casting

Once refined, the molten steel is ready to be cast. The steel is poured into molds to form slabs, billets, or blooms, depending on the intended shape.

Most modern steel plants utilize continuous casting. In this process, molten steel is continuously poured into a water-cooled mold, where it solidifies as it moves downward. This produces long strands of steel that are cut to the desired length. Although ingot casting is still used in some cases, it’s less common today.

6. Forming and Shaping

After the steel solidifies, it undergoes additional shaping to create the final product. This is typically done through hot or cold rolling:

• Hot Rolling: The steel is heated above its recrystallization temperature and passed through large rollers to achieve the desired thickness. This method is used for products like steel sheets, beams, and rails.
• Cold Rolling: For certain applications, the steel is rolled at room temperature. This results in a smoother surface and more precise dimensions, making it ideal for products requiring a high-quality finish.

7. Finishing Processes

The final step in steel production involves a series of finishing treatments that prepare the steel for use in construction, manufacturing, and other industries. These processes include:

• Acid baths (called 'pickling') to remove surface impurities like rust or scale.
• Galvanization, which coats the steel with zinc to prevent rusting.
• Heat treatment to enhance strength, ductility, or toughness.
• Applying protective coatings or colorful paint finishes.
• Cutting to meet specific requirements.

8. Quality Control and Testing

Before steel products are dispatched, they undergo rigorous quality control checks to ensure they meet necessary mechanical properties, chemical compositions, and dimensional tolerances. Common tests include:

• Tensile testing to evaluate the steel’s strength.
• Hardness testing to assess its resistance to indentation.
• Ultrasonic testing to detect internal flaws or cracks.

Once the steel passes these tests and meets the standards, it’s ready to be utilized in a variety of products—from tools and machinery to vehicle frames, furniture, medical equipment, and nearly everything else imaginable!

Choose Clickmetal for Premium Steel and Aluminum

As one of the UK’s leading suppliers of steel and aluminum, we at Clickmetal are deeply committed to the role quality metal plays in shaping the world around us, whether for small DIY projects or large-scale developments. That’s why we source our metals exclusively from trusted suppliers and subject all our custom-cut pieces to meticulous quality control to meet the highest standards. If you’re seeking premium-quality metal for your project, you can count on us to deliver precisely what you need—quickly and at some of the best prices in the UK. Explore our complete range here!