1018 carbon steel, also known as AISI 1018 steel, is a popular low-carbon steel alloy with a wide range of applications. It is often used in structural components, machinery parts, and general engineering applications. In this article, we will explore the properties of 1018 carbon steel, its composition, mechanical characteristics, and common uses.


1018 carbon steel contains primarily iron (Fe) and carbon ©, with trace amounts of other elements. Its chemical composition is as follows:

  • Carbon ©: 0.15% – 0.20%
  • Manganese (Mn): 0.60% – 0.90%
  • Phosphorus (P): 0.04% (maximum)
  • Sulfur (S): 0.05% (maximum)

Mechanical Properties

  1. Tensile Strength: 1018 steel has a relatively low tensile strength compared to higher-carbon steels. Its typical tensile strength ranges from 410 MPa to 790 MPa.
  2. Yield Strength: The yield strength of 1018 carbon steel is around 370 MPa.
  3. Elongation: It exhibits good elongation properties, allowing it to deform significantly before fracture.
  4. Hardness: The hardness of 1018 steel depends on the heat treatment. In its annealed condition, it has a hardness of approximately 126 Brinell (HB). After cold working or heat treatment, the hardness can increase.

Heat Treatment

1018 carbon steel is often supplied in the annealed condition (soft and ductile). However, it can be heat-treated to improve its mechanical properties. Common heat treatments include:

  • Annealing: To soften the steel and improve machinability.
  • Normalizing: To refine the grain structure and enhance uniformity.
  • Quenching and Tempering: To increase hardness and strength.


One of the key advantages of 1018 steel is its excellent machinability. It can be easily machined using conventional methods, including turning, milling, drilling, and grinding. Its low carbon content reduces the risk of work hardening during machining.

Common Applications

  1. Shafts and Axles: 1018 steel is commonly used for making shafts, axles, and other rotating components due to its good machinability and moderate strength.
  2. Fasteners: Bolts, screws, and studs made from 1018 carbon steel are widely used in construction and manufacturing.
  3. General Engineering Components: It finds applications in various engineering components, such as gears, bushings, and couplings.
  4. Automotive Parts: 1018 steel is used in automotive parts like crankshafts, connecting rods, and suspension components.


In summary, 1018 carbon steel is a versatile and cost-effective material with favorable properties for a wide range of applications. Its low alloy content makes it suitable for machining, while its moderate strength ensures reliability in structural and mechanical components.

Next time you encounter 1018 steel, appreciate its simplicity and effectiveness in various industries!

Remember to consult material specifications and engineering guidelines for specific applications to ensure optimal performance.

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