Material specification page for hex keys (allen keys) in Grade 12.9 Steel. Covers the grade designation (class 12.9), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to ISO 2936.
Why Choose Grade 12.9 Steel for Hex Keys (Allen Keys)
The highest common strength class, for high-load machine assembly. For hex keys (allen keys), 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 hex keys (allen keys) 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 Hex Keys (Allen Keys), 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 Hex Keys (Allen Keys) Available in Grade 12.9 Steel
| Wrench size s (mm) | Common bolt sizes | Short leg (mm) | Long leg (mm) | Reference standard |
|---|---|---|---|---|
| 0.7 | M1 | 28 | 51 | ISO 2936 / DIN 911 |
| 0.9 | M1.1 | 28 | 56 | ISO 2936 / DIN 911 |
| 1.0 | M1.2 | 32 | 56 | ISO 2936 / DIN 911 |
| 1.3 | M1.6 | 36 | 63 | ISO 2936 / DIN 911 |
| 1.5 | M2 | 40 | 71 | ISO 2936 / DIN 911 |
| 2.0 | M2.5 | 50 | 90 | ISO 2936 / DIN 911 |
| 2.5 | M3 | 56 | 100 | ISO 2936 / DIN 911 |
| 3.0 | M4 | 63 | 112 | ISO 2936 / DIN 911 |
| 4.0 | M5 | 71 | 125 | ISO 2936 / DIN 911 |
| 5.0 | M6 | 80 | 140 | ISO 2936 / DIN 911 |
| 6.0 | M8 | 90 | 160 | ISO 2936 / DIN 911 |
| 7.0 | --- | 100 | 180 | ISO 2936 / DIN 911 |
| 8.0 | M10 | 112 | 200 | ISO 2936 / DIN 911 |
| 9.0 | --- | 112 | 200 | ISO 2936 / DIN 911 |
| 10.0 | M12 | 125 | 224 | ISO 2936 / DIN 911 |
| 12.0 | M14 | 140 | 250 | ISO 2936 / DIN 911 |
| 14.0 | M16 | 160 | 280 | ISO 2936 / DIN 911 |
| 17.0 | M20 | 180 | 315 | ISO 2936 / DIN 911 |
| 19.0 | M22 | 200 | 355 | ISO 2936 / DIN 911 |
| 22.0 | M24 | 224 | 400 | ISO 2936 / DIN 911 |
| 24.0 | M27 | 250 | 450 | ISO 2936 / DIN 911 |
| 27.0 | M30 | 280 | 500 | ISO 2936 / DIN 911 |
| 32.0 | M36 | 315 | 560 | ISO 2936 / DIN 911 |
| 36.0 | M42 | 355 | 630 | ISO 2936 / DIN 911 |
| 41.0 | M48 | 400 | 710 | ISO 2936 / DIN 911 |
| 46.0 | --- | 450 | 800 | ISO 2936 / DIN 911 |
| 50.0 | --- | 500 | 900 | ISO 2936 / DIN 911 |
| 55.0 | --- | 500 | 900 | ISO 2936 / DIN 911 |
| 60.0 | --- | 560 | 1000 | ISO 2936 / DIN 911 |