Socket Head Cap Screws manufactured in Grade 12.9 Steel (class 12.9) are dimensioned to ISO 4762 / DIN 912. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose Grade 12.9 Steel for Socket Head Cap Screws
The highest common strength class, for high-load machine assembly. For socket head cap 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 |
Corrosion Behavior in Service
Carbon and alloy steel socket head cap screws require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Comparable Grades
For Socket Head Cap 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 Head Cap Screws Available in Grade 12.9 Steel
| Size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Hex key s (mm) | Socket depth t min (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M1 | 0.25 | 1.9 | 1.0 | 0.7 | 0.5 | ISO 4762 / DIN 912 |
| M1.2 | 0.25 | 2.3 | 1.2 | 0.9 | 0.6 | ISO 4762 / DIN 912 |
| M1.4 | 0.3 | 2.6 | 1.4 | 1.0 | 0.7 | ISO 4762 / DIN 912 |
| M1.6 | 0.35 | 3.0 | 1.6 | 1.5 | 0.7 | ISO 4762 / DIN 912 |
| M2 | 0.4 | 3.8 | 2.0 | 1.5 | 1.0 | ISO 4762 / DIN 912 |
| M2.5 | 0.45 | 4.5 | 2.5 | 2.0 | 1.1 | ISO 4762 / DIN 912 |
| M3 | 0.5 | 5.5 | 3.0 | 2.5 | 1.3 | ISO 4762 / DIN 912 |
| M4 | 0.7 | 7.0 | 4.0 | 3.0 | 2.0 | ISO 4762 / DIN 912 |
| M5 | 0.8 | 8.5 | 5.0 | 4.0 | 2.5 | ISO 4762 / DIN 912 |
| M6 | 1.0 | 10.0 | 6.0 | 5.0 | 3.0 | ISO 4762 / DIN 912 |
| M8 | 1.25 | 13.0 | 8.0 | 6.0 | 4.0 | ISO 4762 / DIN 912 |
| M10 | 1.5 | 16.0 | 10.0 | 8.0 | 5.0 | ISO 4762 / DIN 912 |
| M12 | 1.75 | 18.0 | 12.0 | 10.0 | 6.0 | ISO 4762 / DIN 912 |
| M14 | 2.0 | 21.0 | 14.0 | 12.0 | 7.0 | ISO 4762 / DIN 912 |
| M16 | 2.0 | 24.0 | 16.0 | 14.0 | 8.0 | ISO 4762 / DIN 912 |
| M18 | 2.5 | 27.0 | 18.0 | 14.0 | 9.0 | ISO 4762 / DIN 912 |
| M20 | 2.5 | 30.0 | 20.0 | 17.0 | 10.0 | ISO 4762 / DIN 912 |
| M22 | 2.5 | 33.0 | 22.0 | 17.0 | 11.0 | ISO 4762 / DIN 912 |
| M24 | 3.0 | 36.0 | 24.0 | 19.0 | 12.0 | ISO 4762 / DIN 912 |
| M27 | 3.0 | 40.0 | 27.0 | 19.0 | 13.5 | ISO 4762 / DIN 912 |
| M30 | 3.5 | 45.0 | 30.0 | 22.0 | 15.5 | ISO 4762 / DIN 912 |
| M33 | 3.5 | 50.0 | 33.0 | 24.0 | 17.5 | ISO 4762 / DIN 912 |
| M36 | 4.0 | 54.0 | 36.0 | 27.0 | 19.0 | ISO 4762 / DIN 912 |
| M42 | 4.5 | 63.0 | 42.0 | 32.0 | 21.0 | ISO 4762 / DIN 912 |
| M48 | 5.0 | 72.0 | 48.0 | 36.0 | 25.0 | ISO 4762 / DIN 912 |