Property Class 12.9 Steel Slotted Terminal Screws are supplied to ISO 898-1 property class 12.9. Corrosion behaviour is requires plating or black-oxide protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the highest common strength class, for high-load machine assembly.
- Grade
- ISO 898-1 property class 12.9
- Corrosion resistance
- Requires plating or black-oxide protection
- Magnetic response
- Magnetic
- Service temperature
- commonly limited to approx. +300 °C; confirm against the coating and the load
Property values are typical for the grade. Certified mechanical test data is available on request for production orders.
Slotted Terminal Screws manufactured in Property Class 12.9 Steel (ISO 898-1 property class 12.9) are dimensioned to DIN 84. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose Property Class 12.9 Steel for Slotted Terminal Screws
The highest common strength class, for high-load machine assembly. For slotted terminal 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 slotted terminal 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 Slotted Terminal 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 Slotted Terminal Screws Available in Property Class 12.9 Steel
| Thread size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Slot width n (mm) | Slot depth t (mm) | Common length range (mm) | Reference standard |
|---|
| M2.5 | 0.45 | 4.5 | 1.8 | 0.6 | 1.1 | 4~20 | DIN 84 |
| M3 | 0.5 | 5.5 | 2.0 | 0.8 | 1.2 | 4~25 | DIN 84 |
| M3.5 | 0.6 | 6.0 | 2.4 | 1.0 | 1.5 | 5~30 | DIN 84 |
| M4 | 0.7 | 7.0 | 2.6 | 1.2 | 1.6 | 5~35 | DIN 84 |
| M5 | 0.8 | 8.5 | 3.3 | 1.2 | 2.0 | 6~40 | DIN 84 |
| M6 | 1.0 | 10.0 | 3.9 | 1.6 | 2.4 | 8~50 | DIN 84 |
Dimensions are independent of the material: the table above lists the sizes supplied, and on this page every one of them is quoted in Property Class 12.9 Steel. The catalogue's default material column has been omitted here so it cannot be read as contradicting that.
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. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom screw manufacturingSend a drawing
Applications & Industries
Slotted Terminal Screws are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from M2.5 to M6.
Industries that specify Slotted Terminal Screws
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Food, pharma & cleanroom
Stainless assemblies that are washed down, where the finish matters as much as the strength.
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Machine building & OEM
The default fastener on production equipment: covers, brackets, motor mounts and sub-assemblies tightened to a specified torque.
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Automotive & transport
Chassis, driveline and body fixings that see vibration and are assembled to a controlled preload.
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Steel fabrication
Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.
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Energy & infrastructure
Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.
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Maintenance & MRO
Stocked replacements matched to an existing property class, thread and finish.
Typical applications
- joints where the property class is stated on the drawing
- clamping two machined faces to a calculated preload
- bolting brackets, motors and gearboxes to a frame
- assemblies that are dismantled for service and re-torqued
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Torque and preload
- The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.
Where to use something else
- Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.
Full application guide: where Slotted Terminal Screws are used, how to specify them, and the cases they are wrong for
