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| Property | Value |
|---|---|
| DIN Number | DIN EN ISO 898-1, Class 12.9 |
| Tensile Strength | 1220 MPa min |
| Yield Strength | 1100 MPa min (0.2% offset) |
| Hardness | 39-44 HRC |
| Density | 7.85 g/cm³ |
| Maximum Service Temperature | 300°C |
| Element | Composition (%) |
|---|---|
| C | 0.28–0.50 |
| Cr | 0.50–1.20 |
| Mo | 0.15–0.40 |
| Mn | 0.50–1.20 |
| Si | 0.10–0.40 |
| P | ≤0.025 |
| S | ≤0.025 |
Metric Grade 12.9 fasteners are manufactured from medium carbon alloy steel, typically containing chromium, molybdenum, and manganese as primary alloying elements. Chromium enhances hardenability and wear resistance, while molybdenum improves strength retention at elevated temperatures and reduces temper embrittlement. Manganese contributes to deep hardenability during quenching, ensuring uniform mechanical properties throughout the fastener cross-section. Trace additions of boron in some variants further increase hardenability without compromising ductility, allowing the material to achieve the demanding strength requirements specified under ISO 898-1.
These alloying characteristics enable Grade 12.9 fasteners to deliver exceptional tensile and yield strength, making them ideal for high-load structural, automotive, and machinery applications. The quenched and tempered microstructure provides excellent fatigue resistance and dimensional stability under cyclic loading. Although corrosion resistance is limited compared to stainless alternatives, protective coatings such as zinc-flake or phosphate finishes are commonly applied. Combined with reliable heat resistance up to 300°C, this makes Grade 12.9 the preferred choice for demanding high-strength fastening applications.
Specifications
Metric Grade 12.9 Fasteners are high-strength metric components defined by precise dimensional specifications and demanding mechanical properties, including tensile and yield performance suitable for critical assemblies. Designed to align with ISO property class 12.9 requirements, they deliver reliable technical data for engineered fastening applications.
| Property | Value |
|---|---|
| Tensile Strength | 1220 MPa min |
| Yield Strength | 1100 MPa min |
| Elongation | 9% min |
| Reduction of Area | 48% min |
| Hardness | 39-44 HRC |
| Modulus of Elasticity | 200 GPa |
| Thermal Expansion | 11.5 x10⁻⁶/°C |
| Thermal Conductivity | 46 W/m·K |
| Density | 7.85 g/cm³ |
| Melting Range | 1420-1460°C |
| Heat Treatment | Quenched and Tempered |
| Maximum Service Temperature | 300°C |
| Standard | Details |
|---|---|
| Bolt Standard | DIN 931, DIN 933, ISO 4014/4017 |
| Stud Bolt Standard | DIN 976, DIN 938/939 |
| Nut Standard | DIN 934, ISO 4032 |
| Washer Standard | DIN 125, DIN 127 |
| Thread Form | Metric Coarse and Fine (ISO 261/262) |
| Diameter Range | M3 to M100 |
| Length Range | 10mm to 500mm |
| Available Product Forms | Hex Bolts, Studs, Nuts, Washers |
| Custom Sizes | Available on request |
| Manufacturing Standards | ISO 898-1, DIN EN ISO 3506 |
| Inspection Standards | ISO 6157, EN 10204 3.1 |
Applications
