Property Class 8.8 Steel (ISO 898-1 property class 8.8) is the workhorse medium-carbon alloy class for structural joints. When hex head bolts with reduced shank are specified in this grade, the dimensions remain per ISO 4015; the material determines corrosion behavior (requires plating (zinc) for corrosion protection) and the service temperature range (commonly limited to approx. +300 °C; confirm against the coating and the load). Both are covered below with the size table.
Why Choose Property Class 8.8 Steel for Hex Head Bolts with Reduced Shank
The workhorse medium-carbon alloy class for structural joints. For hex head bolts with reduced shank, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 8.8 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
Galvanic & Galling Considerations
For hex head bolts with reduced shank in steel, the dominant compatibility issue is hydrogen embrittlement at high property classes (10.9 and above) when electroplated. Plating must be followed by an appropriate baking treatment, or a non-electroplated finish (mechanical zinc, zinc flake) should be substituted.
Comparable Grades
For Hex Head Bolts with Reduced Shank, class 10.9 or 12.9 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.
Sizes of Hex Head Bolts with Reduced Shank Available in Property Class 8.8 Steel
| Size | Pitch P (mm) | b1 (mm) | b2 (mm) | c_max (mm) | d_a_max (mm) | d_s (mm) | d_w_min (mm) | Width across corners e (mm) | Head height k (mm) | k_max (mm) | k_min (mm) | k_w_min (mm) | r_min (mm) | Width across flats s (mm) | s_min (mm) | x_max (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 12 | 0 | 0.4 | 3.6 | 2.6 | 4.72 | 5.88 | 2 | 2.2 | 1.8 | 1.26 | 0.1 | 5.5 | 5.2 | 1.25 | 20~30 | ISO 4015 |
| (M3.5) | 0.6 | 13 | 0 | 0.4 | 4.1 | 3.05 | 5.22 | 6.44 | 2.4 | 2.6 | 2.2 | 1.54 | 0.1 | 6 | 5.7 | 1.5 | 20~35 | ISO 4015 |
| M4 | 0.7 | 14 | 0 | 0.4 | 4.7 | 3.5 | 6.06 | 7.5 | 2.8 | 3 | 2.6 | 1.82 | 0.2 | 7 | 6.64 | 1.75 | 20~40 | ISO 4015 |
| M5 | 0.8 | 16 | 0 | 0.5 | 5.7 | 4.4 | 7.06 | 8.63 | 3.5 | 3.74 | 3.26 | 2.28 | 0.2 | 8 | 7.64 | 2 | 25~50 | ISO 4015 |
| M6 | 1 | 18 | 0 | 0.5 | 6.8 | 5.3 | 8.74 | 10.89 | 4 | 4.24 | 3.76 | 2.63 | 0.25 | 10 | 9.64 | 2.5 | 25~60 | ISO 4015 |
| (M7) | 1 | 20 | 0 | 0.6 | 7.8 | 6.2 | 9.47 | 11.94 | 4.8 | 5.04 | 4.56 | 3.19 | 0.25 | 11 | 10.57 | 2.5 | 30~70 | ISO 4015 |
| M8 | 1.25 | 22 | 0 | 0.6 | 9.2 | 7.1 | 11.47 | 14.2 | 5.3 | 5.54 | 5.06 | 3.54 | 0.4 | 13 | 12.57 | 3.2 | 30~80 | ISO 4015 |
| M10 | 1.5 | 26 | 0 | 0.6 | 11.2 | 8.9 | 14.97 | 17.59 | 6.9 | 6.69 | 6.11 | 4.28 | 0.4 | 16 | 15.57 | 3.8 | 40~100 | ISO 4015 |
| M12 | 1.75 | 30 | 0 | 0.6 | 13.7 | 10.7 | 16.47 | 19.85 | 7.5 | 7.79 | 7.21 | 5.05 | 0.6 | 18 | 17.57 | 4.3 | 45~120 | ISO 4015 |
| (M14) | 2 | 34 | 40 | 0.6 | 15.7 | 12.5 | 19.15 | 22.78 | 8.8 | 9.09 | 8.51 | 5.96 | 0.6 | 21 | 20.16 | 5 | 50~140 | ISO 4015 |
| M16 | 2 | 38 | 44 | 0.8 | 17.7 | 14.5 | 22 | 26.17 | 10 | 10.29 | 9.71 | 6.8 | 0.6 | 24 | 23.16 | 5 | 55~150 | ISO 4015 |
| (M18) | 2.5 | 42 | 48 | 0.8 | 20.2 | 16.3 | 24.85 | 29.56 | 11.5 | 11.85 | 11.15 | 7.81 | 0.6 | 27 | 26.16 | 6.3 | 60~150 | ISO 4015 |
| M20 | 2.5 | 46 | 52 | 0.8 | 22.4 | 18.2 | 27.7 | 32.95 | 12.5 | 12.85 | 12.15 | 8.51 | 0.8 | 30 | 29.16 | 6.3 | 65~150 | ISO 4015 |
Dimensions are independent of the material: every size above is available in Property Class 8.8 Steel.
Custom manufacturing · Made to drawing
Need this bolt in a grade that is not listed?
Grade 8 8 Steel is one of the grades the catalog describes. Head form and drive can be specified to the assembly rather than to a standard: a larger bearing face, a security drive, or a socket sized for the tool already on the bench. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
