Grade 8.8 Steel Cylindrical Roller Bearing — ISO / DIN (Series 139) pairs the standard ISO / DIN with a Grade 8.8 Steel base material. The sections below cover why engineers select this grade for cylindrical roller bearing — iso / din (series 139), its corrosion and temperature behavior, and the sizes available.
Why Choose Grade 8.8 Steel for Cylindrical Roller Bearing — ISO / DIN (Series 139)
The workhorse medium-carbon alloy grade for structural joints. For cylindrical roller bearing — iso / din (series 139), 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 |
Corrosion Behavior in Service
Carbon and alloy steel cylindrical roller bearing — iso / din (series 139) 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 Cylindrical Roller Bearing — ISO / DIN (Series 139), 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 Cylindrical Roller Bearing — ISO / DIN (Series 139) Available in Grade 8.8 Steel
| Bore d (mm) | Outer diameter D (mm) | Width B (mm) | Dynamic load C (kN) | Limit speed (rpm) | Reference standard |
|---|---|---|---|---|---|
| 20 | 47 | 14 | 28.4 | 11000 | ISO 246 / GB/T 283 |
| 25 | 52 | 15 | 33.5 | 10000 | ISO 246 / GB/T 283 |
| 30 | 62 | 16 | 49.5 | 8500 | ISO 246 / GB/T 283 |
| 35 | 72 | 17 | 67.0 | 7500 | ISO 246 / GB/T 283 |
| 40 | 80 | 18 | 78.0 | 6700 | ISO 246 / GB/T 283 |
| 50 | 90 | 20 | 93.0 | 6000 | ISO 246 / GB/T 283 |
| 60 | 110 | 22 | 138 | 5000 | ISO 246 / GB/T 283 |
| 75 | 130 | 25 | 180 | 4300 | ISO 246 / GB/T 283 |
| 90 | 160 | 30 | 238 | 3600 | ISO 246 / GB/T 283 |