+86 (0) 159 5016 9967
sales@fullerkr.com
FULLERKREG DIN 931 partially threaded hexagon bolts are manufactured from A2 stainless steel (SUS304) to Grade A2-70, with a whitened and passivated surface finish. The partially threaded shank — with a smooth unthreaded grip length beneath the head — provides precise shear load transfer through the bolt body, making DIN 931 the preferred choice for structural connections, flanged joints, machinery, and applications where the bolt passes through clearance holes and the thread engages only in the nut or tapped hole.
DIN 931 is the metric equivalent of ISO 4014 and is widely specified in European, Asian, and global engineering standards. Available in sizes M6 through M64 across a comprehensive range of lengths.
| Standard | DIN 931 ≡ ISO 4014 (Partially Threaded Hexagon Head Bolts) |
| Thread | Metric coarse per ISO 261 / DIN 13 |
| Thread Coverage | Partial thread — unthreaded grip length beneath head |
| Head Type | Hexagon head — driven by open-end wrench, ring spanner, or socket |
| Material | A2 Stainless Steel / SUS304 / 1.4301 |
| Grade | A2-70 |
| Surface Finish | Whitened & Passivated |
| Size Range | M6 – M64 |
| Length Range | 25 mm – 300 mm (size-dependent) |
| Related Standard | DIN 933 (fully threaded) | ISO 4017 (fully threaded) | ISO 4014 (partial thread) |
| [Product Photo 1] | [Product Photo 2] | [Product Photo 3] | [Product Photo 4] |
All dimensions in millimeters (mm). Data per DIN 931 / ISO 4014 standard.
| Thread (d) | Pitch (mm) | s — A/F (mm) | e — A/C (mm) | k — Head Height (mm) | ds — Shank Ø (mm) |
|---|---|---|---|---|---|
| M6 | 1.0 | 10 | 11.05 | 4.0 | 5.7 |
| M8 | 1.25 | 13 | 14.38 | 5.3 | 7.64 |
| M10 | 1.5 | 17 | 18.90 | 6.4 | 9.64 |
| M12 | 1.75 | 19 | 21.10 | 7.5 | 11.57 |
| M14 | 2.0 | 22 | 24.49 | 8.8 | 13.57 |
| M16 | 2.0 | 24 | 26.75 | 10.0 | 15.57 |
| M20 | 2.5 | 30 | 33.53 | 12.5 | 19.48 |
| M24 | 3.0 | 36 | 39.98 | 15.0 | 23.48 |
| M27 | 3.0 | 41 | 45.20 | 17.0 | 26.48 |
| M30 | 3.5 | 46 | 50.85 | 18.7 | 29.48 |
| M36 | 4.0 | 55 | 60.79 | 22.5 | 35.38 |
| M42 | 4.5 | 65 | 71.30 | 26.0 | 41.38 |
| M48 | 5.0 | 75 | 82.60 | 30.0 | 47.38 |
| M56 | 5.5 | 85 | 93.56 | 35.0 | 55.26 |
| M64 | 6.0 | 95 | 104.86 | 40.0 | 63.26 |
* s = across flats (A/F); e = across corners (A/C); k = head height; ds = unthreaded shank diameter (max). All dimensions per DIN 931 / ISO 4014.
The threaded length b depends on bolt diameter and nominal length L. Per DIN 931 / ISO 4014:
| Thread (d) | b — L ≤ 125 mm | b — 125 < L ≤ 200 mm | b — L > 200 mm |
|---|---|---|---|
| M6 | 18 | 24 | — |
| M8 | 22 | 28 | — |
| M10 | 26 | 32 | 45 |
| M12 | 30 | 36 | 49 |
| M14 | 34 | 40 | 53 |
| M16 | 38 | 44 | 57 |
| M20 | 46 | 52 | 65 |
| M24 | 54 | 60 | 73 |
| M27 | 60 | 66 | 79 |
| M30 | 66 | 72 | 85 |
| M36 | 78 | 84 | 97 |
| M42 | — | 96 | 109 |
| M48 | — | 108 | 121 |
| M56 | — | — | 137 |
| M64 | — | — | 153 |
* b = threaded length. Grip length = L − b − k (approximate). For short bolts where L ≤ b + k, the bolt may be fully threaded — verify with FULLERKREG for specific length requirements.
| Property | Value |
|---|---|
| Material Designation | A2 / SUS304 / 1.4301 / 0Cr18Ni9 |
| Property Class | A2-70 |
| Tensile Strength (Rm) | ≥ 700 MPa |
| 0.2% Proof Stress (Rp0.2) | ≥ 450 MPa |
| Stress Under Proof Load | ≥ 580 MPa (for d ≤ M39) |
| Hardness | ≤ 250 HV |
| Elongation at Break (A) | ≥ 0.4 d (min. elongation per ISO 3506) |
| Corrosion Resistance | Good — suitable for general outdoor, food-grade, and mild chemical environments |
| Magnetic | Slightly magnetic after cold working |
| Surface Finish | Whitened & Passivated |
| Temperature Range | −50°C to +300°C (continuous service) |
| Feature | DIN 931 (This Product) | DIN 933 / ISO 4017 |
|---|---|---|
| Thread coverage | Partial — unthreaded grip length beneath head | Full — threaded to within 2 pitches of head |
| Shear load transfer | Excellent — smooth shank carries shear through joint | Reduced — thread root is stress concentration under shear |
| Grip length flexibility | Fixed grip length per standard — less flexible | Maximum flexibility — any grip length possible |
| Structural connections | ✅ Preferred — shank in shear plane | ⚠️ Acceptable but not preferred for shear-critical joints |
| Tapped hole / blind hole | ✅ Suitable — thread engages in nut or tapped hole | ✅ Suitable — maximum thread engagement |
| Vibration resistance | Good — smooth shank reduces fretting | Standard |
| Typical use | Structural steel, flanged joints, machinery, bridges | General fastening, maximum thread engagement needed |
Approximate weights per 100 pieces for common sizes and lengths. Actual weight may vary slightly by batch.
| L (mm) | M6 | M8 | M10 | M12 | M16 | M20 | M24 | M30 | M36 |
|---|---|---|---|---|---|---|---|---|---|
| 25 | 0.14 | 0.29 | — | — | — | — | — | — | — |
| 30 | 0.16 | 0.35 | 0.62 | — | — | — | — | — | — |
| 35 | 0.19 | 0.41 | 0.73 | 1.10 | — | — | — | — | — |
| 40 | 0.22 | 0.47 | 0.84 | 1.27 | 2.50 | — | — | — | — |
| 45 | 0.24 | 0.53 | 0.95 | 1.44 | 2.84 | — | — | — | — |
| 50 | 0.27 | 0.59 | 1.06 | 1.61 | 3.18 | 5.60 | — | — | — |
| 60 | 0.32 | 0.71 | 1.28 | 1.95 | 3.86 | 6.80 | 11.2 | — | — |
| 70 | 0.37 | 0.83 | 1.50 | 2.29 | 4.54 | 8.00 | 13.2 | — | — |
| 80 | 0.43 | 0.95 | 1.72 | 2.63 | 5.22 | 9.20 | 15.2 | 28.0 | — |
| 90 | 0.48 | 1.07 | 1.94 | 2.97 | 5.90 | 10.4 | 17.2 | 31.8 | — |
| 100 | 0.53 | 1.19 | 2.16 | 3.31 | 6.58 | 11.6 | 19.2 | 35.6 | 60.0 |
| 120 | 0.64 | 1.43 | 2.60 | 3.99 | 7.94 | 14.0 | 23.2 | 43.2 | 72.8 |
| 140 | 0.74 | 1.67 | 3.04 | 4.67 | 9.30 | 16.4 | 27.2 | 50.8 | 85.6 |
| 160 | — | 1.91 | 3.48 | 5.35 | 10.66 | 18.8 | 31.2 | 58.4 | 98.4 |
| 180 | — | 2.15 | 3.92 | 6.03 | 12.02 | 21.2 | 35.2 | 66.0 | 111 |
| 200 | — | 2.39 | 4.36 | 6.71 | 13.38 | 23.6 | 39.2 | 73.6 | 124 |
| 220 | — | — | 4.80 | 7.39 | 14.74 | 26.0 | 43.2 | 81.2 | 137 |
| 240 | — | — | 5.24 | 8.07 | 16.10 | 28.4 | 47.2 | 88.8 | 150 |
| 260 | — | — | — | 8.75 | 17.46 | 30.8 | 51.2 | 96.4 | 163 |
| 280 | — | — | — | 9.43 | 18.82 | 33.2 | 55.2 | 104 | 176 |
| 300 | — | — | — | 10.11 | 20.18 | 35.6 | 59.2 | 112 | 189 |
* Weights are approximate (kg/100 pcs) based on A2 stainless steel density (7.93 g/cm³). Actual weights may vary slightly. Contact FULLERKREG for precise weight certificates.
Q: What is the difference between DIN 931 and DIN 933?
A: DIN 931 is partially threaded — it has an unthreaded smooth shank (grip length) beneath the head, with thread only at the end. DIN 933 is fully threaded from head to tip. DIN 931 is preferred for structural and shear-critical connections where the smooth shank should be in the shear plane. DIN 933 is preferred when maximum thread engagement or grip-length flexibility is needed.
Q: What is the equivalent international standard for DIN 931?
A: DIN 931 is equivalent to ISO 4014 (Hexagon head bolts — Product grades A and B). Both standards specify the same dimensions and thread lengths. DIN 931 is the German national standard; ISO 4014 is the international standard. FULLERKREG DIN 931 bolts are manufactured to both standards.
Q: How do I calculate the grip length for a DIN 931 bolt?
A: Grip length ≈ L − b − k, where L = nominal bolt length, b = threaded length (from the table above), k = head height. For example, M16 × 100: grip ≈ 100 − 44 − 10 = 46 mm. Always verify with the thread length table for the specific L range.
Q: Is A2-70 stainless suitable for structural applications?
A: Yes. A2-70 provides a minimum tensile strength of 700 MPa and proof stress of 450 MPa — suitable for most structural bolting applications. For higher-strength requirements, specify A4-80 or consult a structural engineer for load calculations.
Q: Can stainless steel bolts gall (seize) during installation?
A: Yes. Stainless steel is susceptible to galling (cold welding / thread seizure) when torqued against stainless nuts without lubrication. Apply a small amount of anti-seize compound (copper-based or nickel-based) to threads before installation, especially for larger sizes (M20 and above).
Q: What nut and washer should I use with DIN 931 A2-70 bolts?
A: Use A2 stainless steel hexagon nuts (DIN 934 / ISO 4032) and A2 stainless plain washers (DIN 125 / ISO 7089) to maintain material compatibility and avoid galvanic corrosion. For structural applications, use A2 stainless structural nuts (ISO 4033) as specified.
20% off all Cordless tool kits.
Fresh picks for your outdoor space, just in.