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Product Overview
EN 24 (4340 Equivalent) washers are high-strength alloy steel flat or shaped washers manufactured from EN 24 (AISI 4340) bar or plate, conforming to BS 970 and ASTM A322 standards. This alloy is renowned for its excellent toughness, high tensile strength, and fatigue resistance, making it ideal for critical bolted joints in demanding mechanical and structural applications.
EN 24 washers are typically supplied in the hardened and tempered condition (usually 32-38 HRC), providing superior load distribution and resistance to embedding under high clamp loads. They are widely specified in heavy engineering, automotive, and aerospace assemblies where standard carbon steel washers would fail due to deformation or wear.
| Material | EN 24 (AISI 4340 Equivalent) |
| UNS Number | G43400 |
| DIN Number | 1.6511 |
| Material Standard | BS 970:1991 / ASTM A322 |
| Washer Standard (Metric) | DIN 125 / DIN 127 / DIN 7989 |
| Washer Standard (Inch) | ASME B18.22.1 |
| Type | Flat, Spring, Taper, Spherical |
| Diameter Range | M6-M100 / ¼"-4" |
| Tensile Strength | 850-1000 MPa (123-145 ksi) |
| Yield Strength | 680 MPa (99 ksi) min |
| Hardness | 32-38 HRC |
Complete the Fastener Set
Technical Data
| Size (M) | Inner Dia (mm) | Outer Dia (mm) | Thickness (mm) |
|---|---|---|---|
| M6 | 6.4 | 12 | 1.6 |
| M8 | 8.4 | 16 | 1.6 |
| M10 | 10.5 | 20 | 2.0 |
| M12 | 13.0 | 24 | 2.5 |
| M16 | 17.0 | 30 | 3.0 |
| M20 | 21.0 | 37 | 3.0 |
| M24 | 25.0 | 44 | 4.0 |
| M30 | 31.0 | 56 | 4.0 |
| M36 | 37.0 | 66 | 5.0 |
| M42 | 43.0 | 78 | 6.0 |
| M48 | 49.0 | 92 | 6.0 |
| M56 | 57.0 | 105 | 8.0 |
| M64 | 65.0 | 115 | 8.0 |
| M72 | 73.0 | 130 | 10.0 |
| M80 | 81.0 | 140 | 10.0 |
| M100 | 101.0 | 180 | 12.0 |
| Standard | Covers | Type |
|---|---|---|
| DIN 125 | Flat washers | Metric |
| DIN 127 | Spring lock washers | Metric |
| DIN 7989 | Heavy-duty structural washers | Metric |
| ASME B18.22.1 | Plain & lock washers | Inch |
| BS 4320 | Metric & inch washers | Metric/Inch |
| Material Standard | Requirement |
|---|---|
| BS 970:1991 | EN 24 bar/plate |
| ASTM A322 | 4340 alloy steel |
| EN 10204 3.1 | Mill test certificate |
| EN 10204 3.2 | TPI-witnessed MTC |
Material Chemistry
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.36-0.44 |
| Silicon (Si) | 0.10-0.35 |
| Manganese (Mn) | 0.45-0.70 |
| Nickel (Ni) | 1.30-1.80 |
| Chromium (Cr) | 0.50-1.00 |
| Molybdenum (Mo) | 0.20-0.35 |
| Sulphur (S) | 0.035 max |
| Phosphorus (P) | 0.035 max |
| Iron (Fe) | Balance |
Fastener Performance
| Bolt Size | Recommended Washer OD (mm) | Recommended Thickness (mm) | Max Clamp Load (kN) |
|---|---|---|---|
| M12 | 24 | 2.5 | 60 |
| M16 | 30 | 3.0 | 95 |
| M20 | 37 | 3.0 | 150 |
| M24 | 44 | 4.0 | 210 |
| M30 | 56 | 4.0 | 340 |
| M36 | 66 | 5.0 | 490 |
| M42 | 78 | 6.0 | 670 |
| M48 | 92 | 6.0 | 870 |
Industry Applications
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