Specifying Split Cotter Pins in Grade 12.9 Steel pairs the dimensional form of Split Cotter Pins (ISO 1234 / DIN 94) with the engineering properties of Grade 12.9 Steel. This page explains when to choose the grade, how it behaves in service, and which grades to compare it against.
Why Choose Grade 12.9 Steel for Split Cotter Pins
The highest common strength class, for high-load machine assembly. For split cotter pins, 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 split cotter pins 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 Split Cotter Pins, 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 Split Cotter Pins Available in Grade 12.9 Steel
| Nominal diameter (mm) | Hole dia min (mm) | Hole dia max (mm) | Common length range (mm) | Material | Reference standard |
|---|---|---|---|---|---|
| 0.6 | 0.7 | 0.9 | 6~16 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 0.8 | 0.9 | 1.1 | 6~20 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 1.0 | 1.1 | 1.3 | 8~25 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 1.2 | 1.3 | 1.5 | 8~30 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 1.6 | 1.7 | 1.9 | 10~40 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 2.0 | 2.1 | 2.4 | 12~50 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 2.5 | 2.7 | 3.0 | 14~63 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 3.2 | 3.4 | 3.8 | 18~80 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 4.0 | 4.3 | 4.8 | 22~100 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 5.0 | 5.4 | 5.9 | 25~125 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 6.3 | 6.7 | 7.4 | 32~160 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 8.0 | 8.5 | 9.3 | 40~200 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 10.0 | 10.6 | 11.5 | 50~250 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |
| 13.0 | 13.8 | 14.9 | 63~315 | Low-carbon steel / stainless | ISO 1234 / DIN 94 |