Property Class 12.9 Steel (ISO 898-1 property class 12.9) is the highest common strength class, for high-load machine assembly. Specified on foundation bolts, l and j form it determines the corrosion behaviour (requires plating or black-oxide protection) and the service temperature range (commonly limited to approx. +300 °C; confirm against the coating and the load); the dimensions are ours rather than a standard's, and are listed in full below.
Why Choose Property Class 12.9 Steel for Foundation Bolts, L and J Form
The highest common strength class, for high-load machine assembly. For foundation bolts, l and j form, 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 foundation bolts, l and j form 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 foundation bolts, l and j form 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 Foundation Bolts, L and J Form Available in Property Class 12.9 Steel
| Thread size | Form | Overall length L (mm) | Hook length (mm) | Thread length (mm) | Projection above concrete (mm) | Material | Finish |
|---|---|---|---|---|---|---|---|
| M12 | L | 300 | 50 | 60 | 60 | Class 4.6 / 8.8 steel | Hot-dip galvanised |
| M16 | L | 400 | 65 | 80 | 80 | Class 4.6 / 8.8 steel | Hot-dip galvanised |
| M16 | J | 400 | 80 | 80 | 80 | Class 4.6 / 8.8 steel | Hot-dip galvanised |
| M20 | L | 500 | 80 | 100 | 100 | Class 4.6 / 8.8 steel | Hot-dip galvanised |
| M20 | J | 500 | 100 | 100 | 100 | Class 4.6 / 8.8 steel | Hot-dip galvanised |
| M24 | L | 600 | 100 | 120 | 120 | Class 4.6 / 8.8 steel | Hot-dip galvanised |
| M30 | L | 750 | 120 | 150 | 150 | Class 4.6 steel | Hot-dip galvanised |
Dimensions are independent of the material: every size above is available in Property Class 12.9 Steel.
Custom manufacturing · Made to drawing
Need this bolt in a grade that is not listed?
Grade 12 9 Steel is one of the grades the catalog describes. Dimensions, material, finish and form are specified from the drawing — a bolt outside the standard range is a variation on existing tooling rather than a new design. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
