For flat plain washer in Grade 8.8 Steel, the controlling selection factors are corrosion exposure, strength requirement and service temperature. The grade data for Grade 8.8 Steel (class 8.8) is summarized below together with every size supplied.
Why Choose Grade 8.8 Steel for Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079)
The workhorse medium-carbon alloy grade for structural joints. For flat plain washer — gb/t 95 / iso 7091 (series 079), 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 flat plain washer — gb/t 95 / iso 7091 (series 079) 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.
Galvanic & Galling Considerations
For flat plain washer — gb/t 95 / iso 7091 (series 079) 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.
Sizes of Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079) Available in Grade 8.8 Steel
| For bolt size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness t (mm) | Reference standard |
|---|---|---|---|---|
| M3 | 3.2 | 7.0 | 0.5 | ISO 7089 / GB/T 97.1 |
| M4 | 4.3 | 9.0 | 0.8 | ISO 7089 / GB/T 97.1 |
| M5 | 5.3 | 10.0 | 1.0 | ISO 7089 / GB/T 97.1 |
| M6 | 6.4 | 12.0 | 1.6 | ISO 7089 / GB/T 97.1 |
| M8 | 8.4 | 16.0 | 1.6 | ISO 7089 / GB/T 97.1 |
| M10 | 10.5 | 20.0 | 2.0 | ISO 7089 / GB/T 97.1 |
| M12 | 13.0 | 24.0 | 2.5 | ISO 7089 / GB/T 97.1 |
| M14 | 15.0 | 28.0 | 2.5 | ISO 7089 / GB/T 97.1 |
| M16 | 17.0 | 30.0 | 3.0 | ISO 7089 / GB/T 97.1 |
| M18 | 19.0 | 34.0 | 3.0 | ISO 7089 / GB/T 97.1 |
| M20 | 21.0 | 37.0 | 3.0 | ISO 7089 / GB/T 97.1 |
| M24 | 25.0 | 44.0 | 4.0 | ISO 7089 / GB/T 97.1 |
| M30 | 31.0 | 56.0 | 4.0 | ISO 7089 / GB/T 97.1 |
| M36 | 37.0 | 66.0 | 5.0 | ISO 7089 / GB/T 97.1 |