Hexagon Head Bolts With Shank Half Thread (DIN 931)
Precision-engineered metric hexagon bolts featuring an unthreaded cylindrical shank providing maximum shear capacity across joint planes. Certified under CE EN 15048 and compliant with ISO 4014, UNI 5737, and IS 4014 for structural framing, machinery, and civil engineering.
A DIN 931 bolt is a standardized metric hexagon head bolt engineered with a partially threaded shank. The smooth, unthreaded cylindrical body section under the head matches the nominal diameter, preventing thread notch fatigue and maximizing joint shear capacity across critical structural, civil, and machinery connection planes.
Preserves 100% full nominal shank area across the joint shear plane, avoiding the 20-30% area loss and notch stress concentrations caused by threads.
b = 2d + 6mm (L ≤ 125mm); b = 2d + 12mm (125 < L ≤ 200mm); b = 2d + 25mm (L > 200mm).
Internationally superseded by ISO 4014, EN 24014, and UNI 5737 with identical mechanical properties.
DIN 931 (With Shank) vs DIN 933 (Full Thread)
Features an unthreaded solid shank between the head and threads. Designed so the solid shank intersects the joint shear plane, delivering higher shear resistance and preventing thread shearing.
Threaded completely up to the underside of the head. Best for blind tapped holes in castings or clamping thin plates where thread engagement is needed throughout the entire length.
Technical Specifications (DIN 931 / ISO 4014)
All dimensions in millimeters (mm). Note: ISO 4014 modifies width across flats (s) for M10 (16mm), M12 (18mm), M14 (21mm), and M22 (34mm).
| Size | Pitch | DIN s (min-max) | ISO s (min-max) | Head k (min-max) | Thread b (L≤125) | Thread b (125<L≤200) | Thread b (L>200) | Torque 8.8 (Nm) |
|---|---|---|---|---|---|---|---|---|
| M6 | 1.0 | 9.78 - 10.0 | 9.78 - 10.0 | 3.85 - 4.15 | 18 | 24 | – | 10.1 |
| M8 | 1.25 | 12.73 - 13.0 | 12.73 - 13.0 | 5.15 - 5.45 | 22 | 28 | 41 | 24.6 |
| M10 * | 1.5 | 16.73 - 17.0 | 15.73 - 16.0 | 6.22 - 6.58 | 26 | 32 | 45 | 48.0 |
| M12 * | 1.75 | 18.67 - 19.0 | 17.73 - 18.0 | 7.32 - 7.68 | 30 | 36 | 49 | 84.0 |
| M14 * | 2.0 | 21.67 - 22.0 | 20.67 - 21.0 | 8.62 - 8.98 | 34 | 40 | 53 | 133.0 |
| M16 | 2.0 | 23.67 - 24.0 | 23.67 - 24.0 | 9.82 - 10.20 | 38 | 44 | 57 | 206.0 |
| M20 | 2.5 | 29.67 - 30.0 | 29.67 - 30.0 | 12.28 - 12.70 | 46 | 52 | 65 | 415.0 |
| M22 * | 2.5 | 31.61 - 32.0 | 33.38 - 34.0 | 13.78 - 14.20 | 50 | 56 | 69 | 565.0 |
| M24 | 3.0 | 35.38 - 36.0 | 35.38 - 36.0 | 14.78 - 15.20 | 54 | 60 | 73 | 714.0 |
| M30 | 3.5 | 45.0 - 46.0 | 45.0 - 46.0 | 18.28 - 19.10 | 66 | 72 | 85 | 1420.0 |
| M36 | 4.0 | 53.8 - 55.0 | 53.8 - 55.0 | 22.08 - 22.90 | 78 | 84 | 97 | 2480.0 |
Frequently Asked Questions
What is a DIN 931 hexagon head bolt with shank? ↓
DIN 931 is the German industrial standard (superseded internationally by ISO 4014) specifying hexagon head bolts with a partial thread and smooth unthreaded shank. The unthreaded section matches the full nominal bolt diameter to provide superior shear resistance across joint split lines.
What is the difference between DIN 931 and DIN 933? ↓
DIN 931 has a partial thread with a smooth unthreaded shank under the head. DIN 933 is fully threaded all the way to the head. DIN 931 is preferred for structural connections bearing shear loads, while DIN 933 is best for blind tapped holes.
How is thread length calculated for DIN 931 bolts? ↓
Thread length (b) is defined by standard formulas: for length L ≤ 125mm: b = 2d + 6mm; for 125mm < L ≤ 200mm: b = 2d + 12mm; for L > 200mm: b = 2d + 25mm.
Does BRK Industries provide CE Marking and 3.1 Test Certificates? ↓
Yes. All BRK Industries structural bolts are CE marked under EN 15048 and EN 14399. Every order is traceable with an official EN 10204 Type 3.1 Mill Test Certificate documenting chemical and mechanical verification.