Material specification page for torsion springs in Grade 8.8 Steel. Covers the grade designation (class 8.8), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to DIN 2089.
Why Choose Grade 8.8 Steel for Torsion Springs
The workhorse medium-carbon alloy grade for structural joints. For torsion springs, 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 torsion springs 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 Torsion Springs, 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 Torsion Springs Available in Grade 8.8 Steel
| Wire dia d (mm) | Inner diameter Di (mm) | Outer diameter De (mm) | Length Lo (mm) | Coils n | Torque range | Material | Reference standard |
|---|---|---|---|---|---|---|---|
| 0.5 | 4.0 | 5.0 | 10 | 6 | 5~15Nmm | Spring steel | DIN 2089 |
| 0.6 | 5.0 | 6.2 | 12 | 6 | 8~25Nmm | Spring steel | DIN 2089 |
| 0.8 | 6.0 | 7.6 | 15 | 6 | 18~55Nmm | Spring steel | DIN 2089 |
| 1.0 | 8.0 | 10.0 | 18 | 6 | 35~100Nmm | Spring steel | DIN 2089 |
| 1.2 | 9.0 | 11.4 | 20 | 6 | 65~190Nmm | Spring steel | DIN 2089 |
| 1.5 | 12.0 | 15.0 | 25 | 6 | 150~420Nmm | Spring steel | DIN 2089 |
| 2.0 | 15.0 | 19.0 | 30 | 6 | 380~1100Nmm | Spring steel | DIN 2089 |
| 2.5 | 20.0 | 25.0 | 35 | 6 | 900~2500Nmm | Spring steel | DIN 2089 |
| 3.0 | 25.0 | 31.0 | 40 | 6 | 1800~5000Nmm | Spring steel | DIN 2089 |
| 4.0 | 32.0 | 40.0 | 50 | 6 | 5500~15000Nmm | Spring steel | DIN 2089 |