Material specification page for low cap (acorn) nuts in Property Class 12.9 Steel. Covers the grade designation (ISO 898-1 property class 12.9), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to DIN 917.
Why Choose Property Class 12.9 Steel for Low Cap (Acorn) Nuts
The highest common strength class, for high-load machine assembly. For low cap (acorn) nuts, this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 12.9 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
| Corrosion characteristic | Requires plating or black-oxide protection |
Corrosion Behavior in Service
Carbon and alloy steel low cap (acorn) nuts 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 Low Cap (Acorn) Nuts, 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 Low Cap (Acorn) Nuts Available in Property Class 12.9 Steel
| Size | Pitch P (mm) | g2 (mm) | h (mm) | r (mm) | Width across flats s (mm) | t (mm) | w (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|
| M4 | 0.7 | 1.05 | 5.5 | 8 | 7 | 4.16 | 1 | DIN 917 |
| M5 | 0.8 | 1.2 | 7 | 10 | 8 | 4.96 | 1 | DIN 917 |
| M6 | 1 | 1.5 | 9 | 12 | 10 | 6.71 | 1.5 | DIN 917 |
| M8 | 1.25 | 1.87 | 12 | 15 | 13 | 9.21 | 2 | DIN 917 |
| M10 | 1.5 | 2.25 | 14 | 20 | 17 | 10.65 | 2 | DIN 917 |
| M12 | 1.75 | 6.4 | 16 | 25 | 19 | 13.15 | 2 | DIN 917 |
| (M14) | 2 | 7.3 | 18 | 28 | 22 | 14.65 | 2 | DIN 917 |
| M16 | 2 | 7.3 | 20 | 30 | 24 | 16.65 | 2 | DIN 917 |
| (M18) | 2.5 | 9.3 | 22 | 32 | 27 | 18.58 | 2 | DIN 917 |
| M20 | 2.5 | 9.3 | 25 | 35 | 30 | 20.58 | 2.5 | DIN 917 |
| (M22) | 2.5 | 9.3 | 28 | 35 | 32 | 21.58 | 3 | DIN 917 |
| M24 | 3 | 10.7 | 30 | 40 | 36 | 23.58 | 3 | DIN 917 |
| M30 | 3.5 | 12.7 | 34 | 60 | 46 | 27.58 | 3 | DIN 917 |
| M36 | 4 | 14 | 44 | 70 | 55 | 35.5 | 4 | DIN 917 |
Dimensions are independent of the material: every size above is available in Property Class 12.9 Steel.
Custom manufacturing · Made to drawing
Need this nut in a grade that is not listed?
Grade 12 9 Steel is one of the grades the catalog describes. Thread size is the obvious variable and rarely the interesting one — height for clearance, across-flats for the tool already in the cell, and the locking feature for the vibration actually present. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
