Grade 12.9 Steel Socket Set Screws pairs the standard ISO 4026 / ISO 4029 / DIN 913-916 with a Grade 12.9 Steel base material. The sections below cover why engineers select this grade for socket set screws, its corrosion and temperature behavior, and the sizes available.
Why Choose Grade 12.9 Steel for Socket Set Screws
The highest common strength class, for high-load machine assembly. For socket set screws, this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | class 12.9 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | up to approx. +300 °C |
| Corrosion characteristic | Requires plating or black-oxide protection |
Galvanic & Galling Considerations
For socket set screws 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 Socket Set Screws, class 8.8 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 Socket Set Screws Available in Grade 12.9 Steel
| Size | Pitch (mm) | Hex socket s (mm) | Engagement depth t min (mm) | Point diameter dp (mm) | End type | Reference standard |
|---|---|---|---|---|---|---|
| M1.6 | 0.35 | 0.7 | 0.7 | 0.8 | Flat point | ISO 4026 / DIN 913-916 |
| M1.6 | 0.35 | 0.7 | 0.7 | 0.8 | Cone point | ISO 4027 / DIN 913-916 |
| M1.6 | 0.35 | 0.7 | 0.7 | 0.8 | Dog point | ISO 4028 / DIN 913-916 |
| M1.6 | 0.35 | 0.7 | 0.7 | 0.8 | Cup point | ISO 4029 / DIN 913-916 |
| M2 | 0.4 | 0.9 | 0.9 | 1.0 | Flat point | ISO 4026 / DIN 913-916 |
| M2 | 0.4 | 0.9 | 0.9 | 1.0 | Cone point | ISO 4027 / DIN 913-916 |
| M2 | 0.4 | 0.9 | 0.9 | 1.0 | Dog point | ISO 4028 / DIN 913-916 |
| M2 | 0.4 | 0.9 | 0.9 | 1.0 | Cup point | ISO 4029 / DIN 913-916 |
| M2.5 | 0.45 | 1.3 | 1.1 | 1.5 | Flat point | ISO 4026 / DIN 913-916 |
| M2.5 | 0.45 | 1.3 | 1.1 | 1.5 | Cone point | ISO 4027 / DIN 913-916 |
| M2.5 | 0.45 | 1.3 | 1.1 | 1.5 | Dog point | ISO 4028 / DIN 913-916 |
| M2.5 | 0.45 | 1.3 | 1.1 | 1.5 | Cup point | ISO 4029 / DIN 913-916 |
| M3 | 0.5 | 1.5 | 1.4 | 2.0 | Flat point | ISO 4026 / DIN 913-916 |
| M3 | 0.5 | 1.5 | 1.4 | 2.0 | Cone point | ISO 4027 / DIN 913-916 |
| M3 | 0.5 | 1.5 | 1.4 | 2.0 | Dog point | ISO 4028 / DIN 913-916 |
| M3 | 0.5 | 1.5 | 1.4 | 2.0 | Cup point | ISO 4029 / DIN 913-916 |
| M4 | 0.7 | 2.0 | 2.0 | 2.5 | Flat point | ISO 4026 / DIN 913-916 |
| M4 | 0.7 | 2.0 | 2.0 | 2.5 | Cone point | ISO 4027 / DIN 913-916 |
| M4 | 0.7 | 2.0 | 2.0 | 2.5 | Dog point | ISO 4028 / DIN 913-916 |
| M4 | 0.7 | 2.0 | 2.0 | 2.5 | Cup point | ISO 4029 / DIN 913-916 |
| M5 | 0.8 | 2.5 | 2.5 | 3.5 | Flat point | ISO 4026 / DIN 913-916 |
| M5 | 0.8 | 2.5 | 2.5 | 3.5 | Cone point | ISO 4027 / DIN 913-916 |
| M5 | 0.8 | 2.5 | 2.5 | 3.5 | Dog point | ISO 4028 / DIN 913-916 |
| M5 | 0.8 | 2.5 | 2.5 | 3.5 | Cup point | ISO 4029 / DIN 913-916 |
| M6 | 1.0 | 3.0 | 3.0 | 4.0 | Flat point | ISO 4026 / DIN 913-916 |
| M6 | 1.0 | 3.0 | 3.0 | 4.0 | Cone point | ISO 4027 / DIN 913-916 |
| M6 | 1.0 | 3.0 | 3.0 | 4.0 | Dog point | ISO 4028 / DIN 913-916 |
| M6 | 1.0 | 3.0 | 3.0 | 4.0 | Cup point | ISO 4029 / DIN 913-916 |
| M8 | 1.25 | 4.0 | 4.0 | 5.5 | Flat point | ISO 4026 / DIN 913-916 |
| M8 | 1.25 | 4.0 | 4.0 | 5.5 | Cone point | ISO 4027 / DIN 913-916 |