Grade 8.8 Steel (class 8.8) is the workhorse medium-carbon alloy grade for structural joints. When needle roller bearing are specified in this grade, the dimensions remain per ISO / DIN; the material determines corrosion behavior (requires plating (zinc) for corrosion protection) and the service temperature range (up to approx. +300 °C). Both are covered below with the size table.
Why Choose Grade 8.8 Steel for Needle Roller Bearing — ISO / DIN (Series 134)
The workhorse medium-carbon alloy grade for structural joints. For needle roller bearing — iso / din (series 134), 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 needle roller bearing — iso / din (series 134) 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 Needle Roller Bearing — ISO / DIN (Series 134), 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 Needle Roller Bearing — ISO / DIN (Series 134) Available in Grade 8.8 Steel
| Bore d (mm) | Outer diameter D (mm) | Width B (mm) | Dynamic load C (kN) | Reference standard |
|---|---|---|---|---|
| 8 | 15 | 12 | 7.2 | ISO 1206 / GB/T 309 |
| 10 | 17 | 12 | 8.3 | ISO 1206 / GB/T 309 |
| 12 | 19 | 12 | 9.65 | ISO 1206 / GB/T 309 |
| 15 | 23 | 12 | 12.5 | ISO 1206 / GB/T 309 |
| 20 | 28 | 16 | 18.7 | ISO 1206 / GB/T 309 |
| 25 | 33 | 16 | 22.8 | ISO 1206 / GB/T 309 |
| 30 | 40 | 20 | 33.0 | ISO 1206 / GB/T 309 |
| 40 | 50 | 20 | 42.5 | ISO 1206 / GB/T 309 |