EN24, also known as 817M40 or AISI 4340, is a high-strength, nickel-chromium-molybdenum alloy steel widely used in engineering, aerospace, automotive, die-making, and heavy industrial components. One of the most frequently searched topics about this alloy is its EN 24 hardness in HRC—a crucial property for applications that demand exceptional strength and wear resistance.
EN24 is a high-tensile alloy steel known for:
Due to its ability to attain high hardness through heat treatment, EN24 is commonly used in:
The hardness of EN24 steel varies depending on its condition and heat treatment process. Below are typical hardness ranges:
Hardness: 217 HB – 250 HB (approx. 20–25 HRC)
Hardness: 28–32 HRC
This is the most important category when searching for EN24 hardness in HRC.
Heat EN24 to 820–850°C, furnace cool. Produces machinable hardness around 20–25 HRC.
Heat to 840–880°C and air cool. Results in hardness of around 28–32 HRC.
To achieve maximum EN24 hardness:
Resulting HRC: 50–55 HRC
Tempering reduces brittleness while retaining strength. The final EN24 hardness depends on the tempering temperature:
| Tempering Temperature (°C) | Typical Hardness (HRC) |
|---|---|
| 200°C | 48–50 HRC |
| 300°C | 44–46 HRC |
| 400°C | 38–42 HRC |
| 500°C | 32–36 HRC |
EN24 is chosen where high hardness and strength are mandatory. Applications requiring:
The EN24 hardness in HRC directly determines the performance of the final product.
EN24 remains one of the most widely used high-strength engineering alloy steels due to its excellent hardenability and performance. Understanding the EN 24 hardness in HRC based on various heat treatment conditions helps manufacturers, engineers, and heat treatment companies achieve optimal mechanical properties for precision applications.
Whether you require EN24 in pre-hardened, normalized, or fully hardened & tempered condition, the hardness values play a crucial role in component performance and durability.