Grade 8.8 Steel Extension Spring are stocked to ISO / DIN. The grade provides requires plating (zinc) for corrosion protection and is magnetic; the practical service range is up to approx. +300 °C. Property data, grade comparison and the full size table follow.
Why Choose Grade 8.8 Steel for Extension Spring — ISO / DIN (Series 143)
The workhorse medium-carbon alloy grade for structural joints. For extension spring — iso / din (series 143), 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 extension spring — iso / din (series 143) 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 extension spring — iso / din (series 143) 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 Extension Spring — ISO / DIN (Series 143) Available in Grade 8.8 Steel
| Wire dia d (mm) | Outer diameter De (mm) | Free length Lo (mm) | Initial tension F0 (N) | Rate k (N/mm) | Material | Reference standard |
|---|---|---|---|---|---|---|
| 0.8 | 6 | 30 | 2 | 2.5 | Music wire | DIN 2097 / GB/T 23935 |
| 1.0 | 8 | 40 | 4 | 4.0 | Music wire | DIN 2097 / GB/T 23935 |
| 1.2 | 10 | 50 | 6 | 6.5 | Music wire | DIN 2097 / GB/T 23935 |
| 1.6 | 14 | 70 | 10 | 12.0 | Music wire | DIN 2097 / GB/T 23935 |
| 2.0 | 18 | 90 | 18 | 20.0 | Music wire | DIN 2097 / GB/T 23935 |
| 2.5 | 22 | 120 | 28 | 32.0 | Music wire | DIN 2097 / GB/T 23935 |
| 3.0 | 28 | 150 | 45 | 55.0 | Music wire | DIN 2097 / GB/T 23935 |
| 4.0 | 40 | 200 | 90 | 110.0 | Music wire | DIN 2097 / GB/T 23935 |