• May 26th 2023

When selecting the appropriate steel for a specific application, it is crucial to consider factors such as strength, ductility, and hardness. Two types of carbon steels, 1018 and 1045, are commonly used in various industries, including automotive, construction, and manufacturing. This essay will explore the differences between 1018 and 1045 steels in terms of chemical composition, mechanical properties, and applications, as well as provide a comprehensive summary of their key differences.

Table of Contents

  1. Introduction
  2. Chemical Composition
  3. Mechanical Properties
  4. Applications
  5. Summary


Carbon steel is an iron alloy that contains varying amounts of carbon, which is the primary determinant of its mechanical properties. 1018 and 1045 steels are two types of medium-carbon steels, each containing different carbon percentages. They are both known for their strength, ductility, and weldability, though they have distinct characteristics that make them suitable for specific applications.

Chemical Composition

The chemical composition of steel has a significant effect on its properties, and it is essential to understand the differences between 1018 and 1045 steels to make an informed decision.

1018 Steel

1018 steel is a low-carbon steel with a carbon content of approximately 0.18%. The low carbon content makes it more ductile and more easily welded than higher carbon steels. The other elements in 1018 steel include:

  • Manganese: 0.60-0.90%
  • Phosphorus: 0.04% max
  • Sulfur: 0.05% max

1045 Steel

1045 steel is a medium-carbon steel containing approximately 0.45% carbon. The higher carbon content, compared to 1018 steel, gives it more strength and hardness, but it also makes it less ductile and more challenging to weld. The other elements in 1045 steel include:

  • Manganese: 0.60-0.90%
  • Phosphorus: 0.04% max
  • Sulfur: 0.05% max

Mechanical Properties

The mechanical properties of steel are influenced by its chemical composition and processing methods. This section will compare the mechanical properties of 1018 and 1045 steels regarding tensile strength, yield strength, elongation, hardness, and impact resistance.

Tensile Strength

Tensile strength is the maximum stress that a material can withstand before breaking when stretched. 1045 steel has a higher tensile strength than 1018 steel, making it more suitable for applications that require high strength.

  • 1018 Steel: 440-540 MPa
  • 1045 Steel: 640-700 MPa

Yield Strength

Yield strength is the stress at which a material begins to deform plastically, meaning it will not return to its original shape when the stress is removed. 1045 steel has a higher yield strength compared to 1018 steel.

  • 1018 Steel: 370-420 MPa
  • 1045 Steel: 410-490 MPa


Elongation is a measure of a material's ductility, or its ability to be stretched without breaking. 1018 steel has a higher elongation percentage, making it more ductile and easier to shape than 1045 steel.

  • 1018 Steel: 15-20%
  • 1045 Steel: 10-14%


Hardness is the resistance of a material to deformation, indentation, or scratching. 1045 steel has a higher hardness than 1018 steel, making it more suitable for applications that require wear resistance.

  • 1018 Steel: 120-170 Brinell
  • 1045 Steel: 180-220 Brinell

Impact Resistance

Impact resistance is a measure of a material's ability to absorb energy without breaking or fracturing. 1018 steel has better impact resistance than 1045 steel due to its lower carbon content and greater ductility.

AISI 1018 Steel Equivalent Material

AISI 1045 Steel Equivalent Material


The differences in chemical composition and mechanical properties make 1018 and 1045 steels suitable for various applications.

1018 Steel

  • Automotive components: Due to its excellent ductility, 1018 steel is used in the production of automotive parts such as gears, shafts, and tie rods.
  • Construction: 1018 steel is commonly used in the construction industry for making steel bars, rods, and sheets.
  • Manufacturing: The excellent weldability of 1018 steel makes it a popular choice for manufacturing equipment and machinery components. All About 1018 Steel You Must Know

1045 Steel

  • Gears and shafts: The high strength and hardness of 1045 steel make it suitablefor manufacturing heavy-duty gears and shafts used in various industrial applications.
  • Machine parts: 1045 steel is used in the production of machine parts that require high strength and wear resistance, such as bushings, rollers, and bearings.
  • Tooling: Due to its high hardness, 1045 steel is also used in the production of cutting tools, dies, and molds.


In conclusion, 1018 and 1045 steels are medium-carbon steels with distinct chemical compositions and mechanical properties that make them suitable for various applications. 1018 steel has a lower carbon content, which results in higher ductility, better weldability, and better impact resistance. It is commonly used for automotive components, construction materials, and manufacturing equipment.

On the other hand, 1045 steel has a higher carbon content, leading to increased strength, hardness, and wear resistance. However, it has lower ductility and weldability compared to 1018 steel. 1045 steel is often used for heavy-duty gears, shafts, machine parts, and tooling.

When selecting between 1018 and 1045 steels, it is essential to consider the specific requirements of the application, such as strength, ductility, and weldability, to ensure that the chosen material meets the desired performance characteristics.