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 flanged button head socket screws 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 Flanged Button Head Socket Screws
The highest common strength class, for high-load machine assembly. For flanged button head socket screws, 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 flanged button head socket screws 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 flanged button head socket screws 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 Flanged Button Head Socket Screws Available in Property Class 12.9 Steel
| Thread size | Pitch (mm) | Flange diameter dc (mm) | Head height k (mm) | Hex socket s (mm) | Bearing area vs plain button | Common length range (mm) | Property class |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 7.6 | 1.65 | 2.0 | approx. 1.9x | 5~25 | 10.9 |
| M4 | 0.7 | 9.4 | 2.20 | 2.5 | approx. 1.9x | 6~30 | 10.9 |
| M5 | 0.8 | 11.8 | 2.75 | 3.0 | approx. 2.0x | 8~40 | 10.9 |
| M6 | 1.0 | 14.2 | 3.30 | 4.0 | approx. 2.0x | 10~50 | 10.9 |
| M8 | 1.25 | 18.0 | 4.40 | 5.0 | approx. 2.0x | 12~60 | 10.9 |
| M10 | 1.5 | 22.0 | 5.50 | 6.0 | approx. 2.1x | 16~60 | 10.9 |
Dimensions are independent of the material: every size above is available in Property Class 12.9 Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
Grade 12 9 Steel is one of the grades the catalog describes. Thread size and pitch, length, property class, drive form, head geometry and head marking are all specifiable — the standard part is where it starts, not where it stops. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
