Grade 8.8 Steel Retaining Ring (Circlip) — ISO / DIN (Series 147) pairs the standard ISO / DIN with a Grade 8.8 Steel base material. The sections below cover why engineers select this grade for retaining ring (circlip) — iso / din (series 147), its corrosion and temperature behavior, and the sizes available.
Why Choose Grade 8.8 Steel for Retaining Ring (Circlip) — ISO / DIN (Series 147)
The workhorse medium-carbon alloy grade for structural joints. For retaining ring (circlip) — iso / din (series 147), this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | class 8.8 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | up to approx. +300 °C |
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
Galvanic & Galling Considerations
For retaining ring (circlip) — iso / din (series 147) 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 Retaining Ring (Circlip) — ISO / DIN (Series 147), 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 Retaining Ring (Circlip) — ISO / DIN (Series 147) Available in Grade 8.8 Steel
| Nominal diameter (mm) | Ring diameter d1 (mm) | Groove diameter d2 (mm) | Thickness s (mm) | Type | Reference standard |
|---|---|---|---|---|---|
| 8 | 7.4 | 7.1 | 0.8 | External | DIN 471 / GB/T 894 |
| 10 | 9.3 | 9.0 | 1.0 | External | DIN 471 / GB/T 894 |
| 12 | 11.1 | 10.8 | 1.0 | External | DIN 471 / GB/T 894 |
| 16 | 15.0 | 14.7 | 1.0 | External | DIN 471 / GB/T 894 |
| 20 | 19.0 | 18.7 | 1.2 | External | DIN 471 / GB/T 894 |
| 25 | 23.9 | 23.6 | 1.2 | External | DIN 471 / GB/T 894 |
| 30 | 28.9 | 28.6 | 1.5 | External | DIN 471 / GB/T 894 |
| 40 | 38.5 | 38.2 | 1.75 | External | DIN 471 / GB/T 894 |
| 50 | 48.5 | 48.2 | 2.0 | External | DIN 471 / GB/T 894 |
| 60 | 58.3 | 58.0 | 2.0 | External | DIN 471 / GB/T 894 |
| 80 | 78.0 | 77.7 | 2.5 | External | DIN 471 / GB/T 894 |
| 100 | 98.0 | 97.7 | 3.0 | External | DIN 471 / GB/T 894 |