Specifying Studs & Threaded Rods in Grade 12.9 Steel pairs the dimensional form of Studs & Threaded Rods (DIN 939 / DIN 975) with the engineering properties of Grade 12.9 Steel. This page explains when to choose the grade, how it behaves in service, and which grades to compare it against.
Why Choose Grade 12.9 Steel for Studs & Threaded Rods
The highest common strength class, for high-load machine assembly. For studs & threaded rods, this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | class 12.9 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | up to approx. +300 °C |
| Corrosion characteristic | Requires plating or black-oxide protection |
Galvanic & Galling Considerations
For studs & threaded rods 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 Studs & Threaded Rods, class 8.8 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 Studs & Threaded Rods Available in Grade 12.9 Steel
| Thread size | Pitch (mm) | Point type | Common lengths (mm) | Reference standard | Notes |
|---|---|---|---|---|---|
| M4 | 0.7 | M4 | 10~100 | DIN 939 | Stud, equal thread both ends |
| M5 | 0.8 | M5 | 10~120 | DIN 939 | Stud, equal thread both ends |
| M6 | 1.0 | M6 | 12~160 | DIN 939 | Stud, equal thread both ends |
| M8 | 1.25 | M8 | 16~200 | DIN 939 | Stud, equal thread both ends |
| M10 | 1.5 | M10 | 20~250 | DIN 939 | Stud, equal thread both ends |
| M12 | 1.75 | M12 | 25~300 | DIN 939 | Stud, equal thread both ends |
| M14 | 2.0 | M14 | 30~300 | DIN 939 | Stud, equal thread both ends |
| M16 | 2.0 | M16 | 35~300 | DIN 939 | Stud, equal thread both ends |
| M18 | 2.5 | M18 | 40~300 | DIN 939 | Stud, equal thread both ends |
| M20 | 2.5 | M20 | 45~300 | DIN 939 | Stud, equal thread both ends |
| M22 | 2.5 | M22 | 50~300 | DIN 939 | Stud, equal thread both ends |
| M24 | 3.0 | M24 | 50~300 | DIN 939 | Stud, equal thread both ends |
| M27 | 3.0 | M27 | 55~300 | DIN 939 | Stud, equal thread both ends |
| M30 | 3.5 | M30 | 60~300 | DIN 939 | Stud, equal thread both ends |
| M36 | 4.0 | M36 | 70~300 | DIN 939 | Stud, equal thread both ends |
| M42 | 4.5 | M42 | 80~300 | DIN 940 | Stud, equal thread both ends |
| M48 | 5.0 | M48 | 90~300 | DIN 940 | Stud, equal thread both ends |
| M4 | 0.7 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M5 | 0.8 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M6 | 1.0 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M8 | 1.25 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M10 | 1.5 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M12 | 1.75 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M16 | 2.0 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M20 | 2.5 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M24 | 3.0 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |
| M30 | 3.5 | Fully threaded | 1000/2000/3000 | DIN 975 | Fully threaded rod, cut to length |