Description
Overview
DIN 912 (equivalent to ISO 4762) defines a hexagon socket cap screw with a cylindrical head and full thread. The internal hex drive allows high tightening torque while requiring minimal clearance around the head, making it one of the most widely used fasteners in machinery and precision engineering.
This selected size is specified with diameter M3, length 40 mm, thread M3, pitch 0.5 mm.
Sold in multiples of '100 pieces. 1 Box = '100 pieces.
Material, Grade & Strength
Grade 12.9 is an ultra-high strength alloy steel property class with approximately 1200 MPa tensile strength and 1080 MPa yield strength, widely used for precision machinery and demanding mechanical assemblies.
Finish & Corrosion Protection
Plain finish fasteners are intended for protected environments.
Typical Uses
Commonly used in machine tools, moulds, dies, automation equipment, fixtures, hydraulic systems and industrial machinery.
Technical Tips
- Use the correct hex key or socket bit.
- Counterbored holes provide full seating.
- Follow recognised torque charts for the selected size and grade.
Selection Advice
Select DIN 912 where high tightening torque and a compact head design are required.
Frequently Asked Questions
What is the difference between DIN 912 and ISO 4762? ISO 4762 replaced DIN 912 internationally and the dimensions are generally interchangeable.
Dimensions – DIN 912 / ISO 4762 M3 x 40
| Standard | DIN 912 / ISO 4762 |
|---|---|
| Product | Hexagon socket head cap screw |
| Thread | M3 x 0.5 |
| Length (l) | 40 mm |
| Head diameter (dk) | 5.5 mm |
| Head height (k) | 3 mm |
| Hex key (s) | 2.5 mm |
| Thread length (b) | 18 mm (ref.) |
| Weight (calculated) | 2.49 kg per 1 000 pieces |
Material, Grade & Strength
| Material | High tensile alloy steel, property class 12.9 |
|---|---|
| Property class | 12.9 |
| Tensile strength Rm (min) | 1220 MPa |
| Yield / 0.2% proof Rp0.2 (min) | 1100 MPa |
| Proof load stress | 970 MPa |
| Hardness | 385-435 HV |
| Elongation after fracture (min) | 8 % |
| Matching nut | property class 12 (ISO 898-2) |
Finish & Corrosion Protection
Plain / self colour: No applied coating. Stainless, brass and nylon parts are supplied plain; plain steel parts need oil, paint or protected environments.
DIN 912 data sheet – all sizes
| Size | Thread | Head diameter (dk) | Head height (k) | Hex key (s) | Thread length (b) |
|---|---|---|---|---|---|
| M2 | M2 x 0.4 | 3.8 mm | 2 mm | 1.5 mm | full thread |
| M2.5 | M2.5 x 0.45 | 4.5 mm | 2.5 mm | 2 mm | full thread |
| M3 | M3 x 0.5 | 5.5 mm | 3 mm | 2.5 mm | 18 mm (ref.) |
| M4 | M4 x 0.7 | 7 mm | 4 mm | 3 mm | 20 mm (ref.) |
| M5 | M5 x 0.8 | 8.5 mm | 5 mm | 4 mm | 22 mm (ref.) |
| M6 | M6 x 1 | 10 mm | 6 mm | 5 mm | 24 mm (ref.) |
| M8 | M8 x 1.25 | 13 mm | 8 mm | 6 mm | 28 mm (ref.) |
| M10 | M10 x 1.5 | 16 mm | 10 mm | 8 mm | 32 mm (ref.) |
| M12 | M12 x 1.75 | 18 mm | 12 mm | 10 mm | 36 mm (ref.) |
| M14 | M14 x 2 | 21 mm | 14 mm | 12 mm | 40 mm (ref.) |
| M16 | M16 x 2 | 24 mm | 16 mm | 14 mm | 44 mm (ref.) |
| M18 | M18 x 2.5 | 27 mm | 18 mm | 14 mm | 48 mm (ref.) |
| M20 | M20 x 2.5 | 30 mm | 20 mm | 17 mm | 52 mm (ref.) |
| M22 | M22 x 2.5 | 33 mm | 22 mm | 17 mm | 56 mm (ref.) |
| M24 | M24 x 3 | 36 mm | 24 mm | 19 mm | 60 mm (ref.) |
| M27 | M27 x 3 | 40 mm | 27 mm | 19 mm | 66 mm (ref.) |
| M30 | M30 x 3.5 | 45 mm | 30 mm | 22 mm | 72 mm (ref.) |
| M33 | M33 x 3.5 | 50 mm | 33 mm | 24 mm | 78 mm (ref.) |
| M36 | M36 x 4 | 54 mm | 36 mm | 27 mm | 84 mm (ref.) |
Nominal dimensions per DIN 912 / ISO 4762. Weights are calculated from nominal dimensions and are a guide only (±10%). Values for fit and strength should be confirmed against the standard for critical applications.
Specifications
| Measurement Type | Metric |
|---|---|
| Thread Size | M3 |
| Thread Pitch | 0.5 mm |
| Thread Style | Partial Thread |
| Drive Size | 2.5 mm |
| Drive Type | Hex |
| Head Style | Cap |
| Diameter | M3 |
| Length | 40 mm |
| Material | Hi - Tensile Steel |
| Finish | Plain |
| Grade | Grade 12.9 |
| Standards Met | DIN 912, BS 4168, ISO 4762 |
| Package Quantity | 100 |
| Package Type | Box |