Steel

Steel is a metal alloy composed primarily of iron and carbon, often with added alloying elements to enhance its properties. For a metal to be classified as steel, the carbon content must remain below 2.14%. If the carbon content exceeds this threshold, the material is classified as cast iron.

How is Steel Made?

Modern steel is produced through metallurgical processes in which pig iron (obtained from a blast furnace) is refined. The carbon, sulfur, and phosphorus contents are reduced, and alloying elements such as nickel, chromium, aluminum, manganese, and silicon are added to improve strength, toughness, corrosion resistance, or other properties.

What is Chemical-Heat Treatment?

Chemical-heat treatment, also called thermo-chemical processing, alters the surface composition of steel components. The process involves exposing steel to elevated temperatures in an environment enriched with elements like carbon, nitrogen, or sulfur. The goal is to increase resistance to wear, fatigue, corrosion, or heat. Common methods include:

• Carburizing – adding carbon to the surface
• Nitriding – adding nitrogen
• Carbonitriding – adding both carbon and nitrogen
• Boriding, Sulfiding, Sherardizing – adding boron, sulfur, or zinc, respectively
• Sulfonitriding and Nitrocarburizing – combining nitrogen with sulfur or carbon

Physical and Mechanical Properties

Steel’s mechanical and thermal properties vary depending on its composition. Indicative values include:

• Density: ~7850 kg/m³
• Melting point: ~1539 °C
• Specific heat capacity: ~469 J·kg⁻¹·K⁻¹
• Elastic modulus (E): ~210,000 MPa
• Shear modulus (G): ~81,000 MPa
• Poisson’s ratio (v): ~0.3

Steel Classification by Composition

• Non-alloyed (carbon) steels: Basic steels with minimal alloy content, commonly heat-treated.
• Low-alloy steels: Contain less than 5% alloying elements, allowing for enhanced hardness and strength via heat treatment.
• High-alloy steels: Contain over 5% alloying elements; widely used for specialized functions like corrosion resistance or high-temperature performance.

Steel Classification by Application

• Damascus steel: Made by forging together multiple types of steel, known for strength and flexibility in blades.
• Tool steel: High-carbon and alloyed, ideal for manufacturing cutting and shaping tools.
• Stainless, heat-resistant, and acid-resistant steel: High in chromium (≥8%) and often nickel; resists corrosion and heat.
• Spring steel: Offers high fatigue strength for elastic components like springs and clips.
• Structural steel: Widely used in construction for beams, frames, and reinforcements.
• Electrotechnical steel: Used in transformer cores; contains silicon for improved magnetic properties.
• Deep-drawing and cementation steels: Engineered for forming and surface hardening applications.
• Free-cutting steel: Contains sulfur, manganese, or lead for improved machinability.

Where is Steel Used?

Steel is everywhere: in buildings, bridges, pipelines, tools, machinery, vehicles, and countless consumer products. It offers an exceptional balance of strength, durability, and cost-effectiveness. Its recyclability (saving up to 75% in energy use) makes it a cornerstone of sustainable industrial production.

Steel components are often used as connectors in mixed-material structures (e.g. glass, concrete, wood). Architects and engineers rely on it for projects requiring long spans, load-bearing capacity, or high aesthetic value.

Examples of Steel in Everyday Gear

On our e-shop, you'll find steel in many products—especially knives, multi-tools, machetes, and camp cookware. Common steel grades include:

• 440A, 440B, 440C
• 8CrMoV, AUS 8
• CrNi 18/10
• D2, Niolox, PGK, Sleipner

Note: Some knives may also feature ceramic blades.