Material specification page for wood screws in Grade 12.9 Steel. Covers the grade designation (class 12.9), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to DIN 96 / DIN 97 / DIN 7997.
Why Choose Grade 12.9 Steel for Wood Screws
The highest common strength class, for high-load machine assembly. For wood screws, 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 |
Corrosion Behavior in Service
Carbon and alloy steel wood 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.
Comparable Grades
For Wood Screws, 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 Wood Screws Available in Grade 12.9 Steel
| Nominal diameter (mm) | Head diameter dk (mm) | Head height k (mm) | Head type | Pilot hole (mm) | Common length range (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|
| 2.0 | 3.8 | 1.2 | Countersunk | 1.2 | 10~25 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |
| 2.5 | 4.7 | 1.5 | Countersunk | 1.5 | 12~30 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |
| 3.0 | 5.6 | 1.65 | Countersunk | 1.8 | 12~40 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |
| 3.5 | 6.5 | 1.93 | Countersunk | 2.0 | 16~50 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |
| 4.0 | 7.5 | 2.2 | Countersunk | 2.3 | 16~70 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |
| 4.5 | 8.5 | 2.5 | Countersunk | 2.5 | 20~80 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |
| 5.0 | 9.2 | 2.5 | Countersunk | 3.0 | 20~100 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |
| 6.0 | 11.0 | 3.0 | Countersunk | 3.5 | 30~120 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |
| 8.0 | 14.5 | 4.0 | Countersunk | 5.0 | 40~160 | DIN 97 / DIN 7997 | Slotted/cross wood screw, gimlet point |