1018 Steel vs 4140 Steel – What’s the Difference

1018 Steel vs 4140 Steel

Steel is an essential material in manufacturing, engineering, and construction. However, not all steel is the same, and differences in steel properties can significantly impact their intended application. Two popular types of steel are 1018 and 4140 steel. While both are widely used, understanding their variations is crucial for making informed decisions for your application. In this blog post, we’ll look at the differences between 1018 and 4140 steel to help you choose the right one for your next project.

Difference Between 1018 Steel and 4140 Steel

Chemical Composition

Chemical composition is the primary differentiating factor between 1018 and 4140 steel. 1018 steel is a plain-carbon steel with 0.18% carbon content and low amounts of other elements. In contrast, 4140 steel contains 0.8% to 1.1% chromium, 0.15% to 0.25 % molybdenum, and 0.1% to 0.2% manganese. The higher concentration of alloying elements in 4140 steel results in higher strength, toughness, and wear resistance.

Mechanical Properties

Mechanical properties are crucial to determine the suitability of steel for a specific application. The mechanical properties of 1018 steel include a tensile strength of 420 MPa, yield strength of 350 MPa, and a Brinell Hardness of 126. On the other hand, 4140 steel has a higher tensile strength of 655 MPa, a yield strength of 415 MPa, and a Rockwell hardness of 92. The superior mechanical properties of 4140 steel make it ideal for heavy-duty and high-strength applications.


Machinability refers to the ease of altering the steel’s shape and giving it a specific form. Generally, steel with low carbon content is easy to machine, while high-carbon steel is more challenging. 1018 steel has high machinability due to its low carbon content. The machinability of 4140 steel is lower than 1018 steel due to the presence of alloying elements. However, 4140 steel can still be machined effectively with the right tooling.


Weldability is essential to consider if you plan to weld the steel. 1018 steel has excellent weldability since it contains no significant alloying elements. Welding 4140 steel can be more challenging due to the alloying elements, which can result in cracking. However, 4140 steel can be welded by preheating the steel, using low-hydrogen welding consumables, and post-weld heat treatment.


Cost is another factor that many people consider when choosing between steel types. 1018 steel is typically less expensive than 4140 steel due to its simpler composition. However, the cost difference is application-dependent and may vary depending on the specific requirements.


Choosing the right steel for your application is critical for ensuring safety and optimal performance. While 1018 and 4140 steels have unique characteristics, they differ significantly in chemical composition, mechanical properties, machinability, weldability, and cost. By understanding these differences, you can make an informed decision that best suits your project’s requirements. Always consult a reliable supplier or a steel expert to determine which steel is best for your application.

Harsh Jain

Harsh Jain

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