EN8 vs EN24: Strength, Hardness & Machinability Comparison | Moksh Tubes

EN8 is a medium carbon engineering steel (BS 970 080M40) widely recognized for its excellent machinability, good tensile strength, moderate hardness, and cost-effectiveness. It is one of the most commonly used engineering steels in manufacturing because it offers an ideal balance between mechanical performance and affordability.

Due to its medium carbon content, EN8 can be induction hardened and heat treated to improve its surface hardness while maintaining a tough core. This makes it suitable for a wide range of engineering components subjected to moderate stress and wear.

EN8 is commonly supplied as round bars, bright bars, black bars, flats, shafts, and custom-machined components for automotive, construction, agricultural, and general engineering industries.

EN24 (BS 970 817M40) is a premium nickel-chromium-molybdenum alloy steel designed for high-performance engineering applications. Compared to EN8, EN24 offers significantly higher tensile strength, outstanding toughness, excellent fatigue resistance, and superior wear resistance.

Its alloy composition enables exceptional hardenability, allowing it to maintain high strength even after heat treatment. These characteristics make EN24 the preferred material for manufacturing heavy-duty engineering components that operate under high loads, shock, and continuous stress.

EN24 is widely used in aerospace, automotive, mining, oil & gas, marine, defense, and heavy engineering industries where reliability and long service life are essential.

The chemical composition of engineering steel directly influences its strength, hardness, wear resistance, machinability, and heat treatment response. While EN8 and EN24 share a similar carbon content, the major difference lies in the alloying elements present in EN24. Nickel, chromium, and molybdenum significantly enhance its mechanical properties, making it suitable for high-performance engineering applications.

EN8 is a medium carbon steel that provides a good balance of strength and machinability, making it ideal for general engineering components. EN24, on the other hand, is an alloy steel specifically developed for heavy-duty applications where superior strength, toughness, and fatigue resistance are required.

Key Difference: The presence of nickel, chromium, and molybdenum in EN24 provides superior hardenability, increased tensile strength, enhanced toughness, and better wear resistance. These alloying elements enable EN24 to maintain excellent mechanical properties even after heat treatment, making it suitable for critical engineering applications.

EN8 does not contain these alloying elements, making it easier to machine and more economical, but less suitable for extremely demanding environments.

Mechanical properties determine how a steel grade performs under different loading conditions. Tensile strength, hardness, toughness, fatigue resistance, and wear resistance all play a vital role in selecting the right engineering steel for industrial applications.

EN24 consistently outperforms EN8 in most mechanical properties due to its alloy composition. However, EN8 remains one of the best choices for medium-duty applications because of its excellent machinability and lower manufacturing costs.

Summary: If your project requires high mechanical performance, EN24 is the preferred option. If cost, machining efficiency, and general engineering performance are more important, EN8 offers excellent value.

Strength is often the deciding factor when selecting an engineering steel. EN24 provides substantially higher tensile and yield strength than EN8 due to the addition of nickel, chromium, and molybdenum. These alloying elements improve the steel's ability to withstand heavy loads, impact, and cyclic stresses.

EN24 is widely used for manufacturing crankshafts, transmission shafts, aerospace components, heavy-duty gears, mining equipment, and oil & gas machinery because it maintains excellent strength under demanding operating conditions.

EN8, although not as strong as EN24, offers sufficient strength for a wide range of general engineering applications such as shafts, bolts, pins, studs, and machine components.

Winner: EN24 - If your application requires maximum strength, long service life, and reliable performance under heavy loads, EN24 is the better choice.

Hardness determines how well a material resists wear, scratching, abrasion, and surface deformation. EN24 can achieve significantly higher hardness after heat treatment, making it ideal for high-performance engineering components exposed to severe operating conditions.

EN8 can also be induction hardened, but its maximum achievable hardness is lower than that of EN24. As a result, EN24 offers superior wear resistance and longer service life in abrasive environments.

Winner: EN24 - Choose EN24 for gears, pinions, heavy-duty shafts, mining equipment, and industrial machinery where high hardness and wear resistance are essential.

Machinability refers to how easily a material can be cut, drilled, turned, milled, or threaded during manufacturing. EN8 is widely recognized for its excellent machinability, making it one of the most economical engineering steels for machining operations.

Its lower alloy content reduces cutting forces, improves tool life, and allows manufacturers to achieve better surface finishes while reducing production costs.

EN24 is more difficult to machine because of its higher alloy content and increased strength. Although it can be machined effectively using appropriate cutting tools and machining parameters, it generally requires more time and higher tooling costs than EN8.

Winner: EN8 - If your manufacturing process involves extensive machining operations and cost efficiency is a priority, EN8 is the better option.

Heat treatment is used to improve the mechanical properties of engineering steels by increasing hardness, strength, toughness, and wear resistance.

Both EN8 and EN24 can be heat treated, but EN24 responds significantly better because of its nickel-chromium-molybdenum alloy composition.

EN8 Heat Treatment: EN8 is commonly subjected to Annealing, Normalizing, Tempering, Flame Hardening, and Induction Hardening. These processes improve surface hardness while maintaining a tough core, making EN8 suitable for general engineering applications.

EN24 Heat Treatment: EN24 is typically heat treated through Annealing, Oil Quenching, Tempering, and Stress Relieving. These treatments significantly increase strength, toughness, and fatigue resistance, enabling EN24 to perform reliably in demanding industrial environments.

EN8 steel is widely used in general engineering applications where a combination of good strength, excellent machinability, moderate hardness, and cost-effectiveness is required. Its balanced mechanical properties make it one of the most popular engineering steels for manufacturing machine components that operate under medium loads and moderate wear conditions.

Because EN8 can be induction hardened, it is suitable for components requiring improved surface hardness while maintaining a tough core. Industries such as automotive, construction, agriculture, manufacturing, and industrial machinery extensively use EN8 steel for producing reliable engineering components.

EN24 is designed for heavy-duty engineering applications where superior tensile strength, excellent toughness, and outstanding fatigue resistance are essential. Due to its nickel-chromium-molybdenum alloy composition, EN24 performs exceptionally well under high loads, impact, cyclic stress, and harsh operating conditions.

Its excellent hardenability and wear resistance make it one of the most preferred engineering steels for critical industrial applications where failure is not an option.

Many engineers compare EN grades with international standards before selecting materials. The following table provides commonly accepted equivalent grades for EN8 and EN24.

Note: Equivalent grades may have slight variations in chemical composition and mechanical properties depending on the applicable international standard and manufacturer.

Choosing between EN8 and EN24 depends on your project requirements rather than simply selecting the stronger material. Consider the following factors before making your decision.