EN24

EN24 Alloy Steel Product Overview

EN24, also known as 817M40 or AISI 4340, is a high-strength, low-alloy nickel-chromium-molybdenum steel under the BS 970 standard. Renowned for its exceptional toughness, high tensile strength, and excellent fatigue resistance, EN24 is ideal for applications requiring robust performance under high stress and dynamic loads. Typically supplied in the annealed condition (max 248 HB) or hardened and tempered (28–36 HRC), it offers good machinability, wear resistance, and shock resistance. Its high alloy content ensures deep hardenability, making it suitable for large components in demanding environments.

Applications

EN24 is widely used in industries requiring high-strength, durable components:

Engineering Components:

• Gears, pinions, and sprockets for heavy machinery and automotive applications.
• Crankshafts, axles, and propeller shafts.
• High-strength bolts, studs, and couplings.

Aerospace:

• Landing gear components, structural parts, and engine mounts.
• High-load fittings and fasteners.

Oil and Gas:

• Drill collars, pump shafts, and valve components for high-pressure environments.
• Heavy-duty components in exploration and production equipment.

Other Uses:

• Power generation components, such as turbine shafts and rotors.
• Tool holders, forging dies, and die blocks.
• Heavy-duty machinery parts in mining and construction, like spindles and rams.

Chemical Composition

The chemical composition of EN24 ensures its strength, toughness, and hardenability:

• Nickel (Ni): Enhances toughness, fatigue resistance, and impact strength.
• Chromium (Cr): Improves hardenability, wear resistance, and corrosion resistance.
• Molybdenum (Mo): Increases strength and resistance to tempering.
• Carbon (C): Provides hardness while maintaining ductility.

Supply Size

EN24 is available in various forms and sizes to meet industrial requirements:

• Round Bars: Diameter 16 mm to 700 mm.
• Flat Bars: Minimum: 10 mm thickness x 80 mm width. Maximum: 500 mm thickness x 2000 mm width.