EN24 Alloy Steel - 817M40

EN24 (817M40, W.Nr 1.6565) is a nickel chromium molybdenum alloy steel that conforms to the BS 970 standards. It is the British Standard equivalent to the 4340 alloy steel, as it has a very similar composition and mechanical properties, thus replacing 4340 in several applications.

The strength of EN24 is acquired by quench and temper heat treatment. With the T temper, it has a tensile strength of 850 MPa and proof stress of 680 MPa and is applicable in applications requiring high strength steels. Higher strength temper conditions can be achieved by increased heat treatment, giving up to a tensile strength of 1550 MPa in structural applications. The nickel content (1.30-1.70%) increases the toughness and impact resistance, chromium (1.00-1.40%) hardenability and molybdenum (0.20-0.35%) increases strength and temper brittleness resistance.

Due to its very good hardenability, EN24 retains the same mechanical properties throughout larger sections, which is an important feature in shafts, gears and other structural parts. Due to the properties of high strength, toughness and fatigue resistance, EN24 is one of the most widely used alloy steels in UK engineering.

EN24 is offered in bar, sheet and plate form by Dynamic Metals in various sizes suitable for prototyping or production.