1. EN8 (080M40)
Type: Medium Carbon Steel
Composition:
Carbon: 0.35–0.45%
Manganese: 0.60–1.00%
Silicon: up to 0.05%
Tensile Strength: 550–700 MPa
Hardness: 200–250 HB
Applications: Shafts, studs, bolts, axles, keys, general engineering parts.
Features: Good tensile strength, can be surface-hardened.
⚙️ 2. EN9 (070M55)
Type: Medium Carbon Steel (Higher carbon than EN8)
Composition:
Carbon: 0.50–0.60%
Manganese: 0.50–0.80%
Tensile Strength: 600–800 MPa
Hardness: 200–300 HB
Applications: Gears, crankshafts, cams, rollers, and springs.
Features: Tough and wear-resistant; can be flame or induction hardened.
3. EN19 (708M40 / AISI 4140 equivalent)
Type: Alloy Steel (Chromium-Molybdenum)
Composition:
Carbon: 0.35–0.45%
Chromium: 0.90–1.20%
Molybdenum: 0.20–0.40%
Tensile Strength: 850–1000 MPa (heat-treated)
Applications: High-stress parts like shafts, gears, connecting rods, spindles.
Features: Excellent toughness, fatigue strength, and wear resistance.
⚙️ 4. EN24 (817M40 / AISI 4340 equivalent)
Type: Nickel-Chromium-Molybdenum Steel
Composition:
Carbon: 0.36–0.44%
Nickel: 1.30–1.80%
Chromium: 0.90–1.40%
Molybdenum: 0.25–0.35%
Tensile Strength: 850–1000 MPa (quenched & tempered)
Applications: Aircraft shafts, heavy-duty gears, bolts, and couplings.
Features: Very high tensile strength, toughness, and shock resistance.
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⚙️ 5. EN31
Type: High Carbon Alloy Steel (Bearing steel)
Composition:
Carbon: 0.95–1.20%
Chromium: 1.00–1.60%
Tensile Strength: up to 750–1000 MPa
Applications: Bearings, rollers, ball races, dies, punches.
Features: High hardness and wear resistance after heat treatment.
