EN 8/9

EN8 and EN9 Alloy Steel Product Overview

EN8 and EN9 are medium-carbon, unalloyed steels under the BS 970 standard, widely used for their good tensile strength, machinability, and versatility in engineering applications. EN8 (080M40) is a medium-carbon steel with good strength and ductility, suitable for components requiring moderate wear resistance. EN9 (070M55) has a higher carbon content, offering greater hardness and strength but slightly reduced ductility. Both are typically supplied in the annealed or normalised condition (EN8: max 207 HB, EN9: max 255 HB) and can achieve 22–28 HRC (EN8) or 28–35 HRC (EN9) after quenching and tempering. These steels are cost-effective and widely used for general-purpose engineering components.

Applications

EN8 and EN9 are used in a variety of engineering and industrial applications requiring moderate to high strength:

EN8 Applications:

• Shafts, axles, and spindles for automotive and machinery.
• Bolts, studs, and high-tensile fasteners.
• Crankshafts, connecting rods, and gear components.
• General-purpose machine parts like couplings and bushings.

EN9 Applications:

• High-strength components like gears, sprockets, and pinions.
• Forging dies, punches, and tool holders for moderate wear.
• Heavy-duty machinery parts in construction and mining.
• Camshafts, rollers, and high-load structural components.

Common Uses:

• Agricultural equipment, hydraulic components, and jigs.
• Medium-duty engineering parts requiring good machinability and strength.

Chemical Composition

The chemical compositions of EN8 and EN9 provide their strength, hardness, and machinability:

EN8 (080M40)

EN9 (070M55)

• Carbon (C): Provides hardness and strength (higher in EN9 for greater hardness).
• Manganese (Mn): Enhances strength and hardenability.
• Silicon (Si): Improves strength and elasticity.
• Phosphorus (P) and Sulfur (S): Kept low to minimise brittleness and improve machinability.

Supply Size

EN8 and EN9 are 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.