Heat Treatment of EN24

EN24 steel is a popular alloy known for its exceptional strength and durability, making it a preferred choice for various industrial applications. One of the key factors responsible for its outstanding properties is the heat treatment process.

In this blog post, we will explore the heat treatment techniques employed for EN24 steel and their impact on its mechanical characteristics.

EN24 Steel Chemical Compositions

The chemical composition of EN24 steel are:

ElementPercentage Range
Carbon (C)0.36 – 0.44%
Silicon (Si)0.10 – 0.35%
Manganese (Mn)0.45 – 0.70%
Phosphorus (P)0.035% max
Sulfur (S)0.040% max
Chromium (Cr)1.00 – 1.40%
Molybdenum (Mo)0.20 – 0.35%
Nickel (Ni)1.30 – 1.70%

Hardening EN24 Steel

To achieve optimal hardness and strength, the EN24 steel is heated uniformly to a temperature range of 823-850°C. It is crucial to ensure thorough heating throughout the material. Once heated through, the steel is rapidly quenched in oil. This quenching process facilitates the transformation of the steel’s microstructure, resulting in increased hardness.

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Hardening EN24 steel involves a specific set of steps to achieve the desired hardness and strength. Here is a breakdown of the process:

  1. Heating: Heat the EN24 steel further to the hardening temperature range of 830-850°C. It is crucial to maintain a uniform and consistent temperature throughout the steel.
  2. Soaking: Once the steel has reached the desired hardening temperature, allow it to soak at this temperature for a sufficient period. The recommended soaking time is generally around 1 hour per inch of the thickest section of the steel.
  3. Quenching: After the soaking period, it’s time to rapidly quench the EN24 steel. The recommended quenching medium for EN24 steel is oil, as it provides a suitable balance of cooling rate and uniformity.
  4. Post-Quenching Tempering: Following the quenching process, the EN24 steel may be subjected to tempering to relieve internal stresses and improve toughness. Tempering typically involves reheating the steel to a lower temperature range, such as 250-375°C, depending on the desired properties. 
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Tempering EN24 Steel

Following the hardening process, tempering plays a vital role in relieving internal stresses and enhancing the toughness of the steel. The EN24 steel is heated uniformly to the desired tempering temperature, typically up to 660°C.

It is important to hold the steel at this temperature for a specific duration, typically two hours per inch of total thickness. However, it is advised to avoid tempering temperatures between 250-375°C, as it may adversely affect the impact value of the steel.

Stress Relieving of EN24 Steel

EN24 steel can undergo stress relieving to alleviate any residual stresses that may have developed during the manufacturing or heat treatment processes. The steel is gradually heated to a temperature range of 650-670°C and soaked for an adequate period. Subsequently, the EN24 tool is cooled either in a controlled furnace environment or by air cooling.

Annealing EN24

In certain cases, where hardening from the T condition is required, a full annealing process is recommended prior to heat treatment. Standard annealing for EN24T involves a slow and uniform heating process to a temperature range of 840-860°C, followed by controlled cooling in the furnace to 580°C. Finally, the steel is allowed to cool to room temperature naturally.

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Tailoring Heat Treatment

It is important to note that heating, cooling, and soaking times may vary depending on factors such as the size and shape of the component. Therefore, it is advisable to consult heat treatment providers who can offer a comprehensive range of heat treatment processes tailored to specific requirements.

These processes may include hardening and tempering, plasma nitriding, nitriding, case hardening, carburizing, nitrocarburizing, induction hardening, flame hardening, stress relieving, and annealing.


Heat treatment plays a crucial role in unlocking the full potential of EN24 steel. By carefully controlling the heating, quenching, and tempering processes, the mechanical properties of EN24 can be optimized to meet the specific demands of various industrial applications.

Whether it’s enhancing hardness, improving toughness, or relieving internal stresses, the right heat treatment strategy can significantly enhance the strength and performance of EN24 steel, making it a reliable choice for critical components in industries ranging from automotive to aerospace.