Steel - Types, Designations, Classification, and Standards

Steel is one of the most important engineering materials, widely used in various industries. Its mechanical and chemical properties can be modified through appropriate production and processing techniques, allowing for the creation of steel with diverse characteristics. In this article, we will discuss the types of steel, their designations, classification, and the standards regulating their production and use.

Types of Steel

Carbon Steel

Carbon steel primarily contains iron and carbon, without significant amounts of other alloying elements. Depending on the carbon content, carbon steel can be divided into:

• Low Carbon Steel (up to 0.3% C): characterized by good ductility and ease of machining.
• Medium Carbon Steel (0.3% - 0.6% C): has higher strength and hardness but less ductility.
• High Carbon Steel (above 0.6% C): is very hard and strong, used for tools and components under high loads.

Alloy Steel

Alloy steel contains alloying elements such as chromium, nickel, molybdenum, or vanadium, which enhance its properties. It can be divided into:

• Stainless Steel: contains a minimum of 10.5% chromium, which provides corrosion resistance.
• Tool Steel: contains alloying elements that increase its hardness and wear resistance.
• Structural Steel: has good strength and ductility, used in construction and mechanical engineering.

Steel Designations

In Poland and Europe, the designation system conforms to the PN-EN 10027 standard. These designations provide information about the chemical composition and mechanical properties of the steel. Example designations:

• Low Carbon Steel: S235JR – where "S" stands for structural steel, "235" is the minimum yield strength in MPa, and "JR" denotes impact properties at 20°C.
• Stainless Steel: X5CrNi18-10 – where "X" denotes high-alloy steel, "5" indicates the carbon content in hundredths of a percent, and "CrNi18-10" specifies the chromium and nickel content in percent.

Steel Classification

Steel can be classified in various ways, depending on the division criterion:

• By Chemical Composition: carbon steel, alloy steel.
• By Application: structural steel, tool steel, stainless steel.
• By Processing Methods: hot-rolled steel, cold-rolled steel.

Steel Standards

Standards regulating the production and use of steel aim to ensure high quality and safety. In Europe, the main standard is EN 10025, which specifies requirements for structural steels. Other important standards include:

• EN 10088: concerning stainless steels.
• EN 10132: concerning cold-rolled steels.
• ISO 4957: concerning tool steels.

Adherence to Standards and Quality

Knowledge of the types, designations, classifications, and standards of steel is crucial for engineers and specialists in the metal industry. Proper selection of steel ensures the durability, strength, and safety of structures and machine components. Compliance with quality standards and norms is fundamental in the production and processing of steel, translating to the quality and reliability of the final products.

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