Property Class 8.8 Steel 12-Point Flange Screws are supplied to ISO 898-1 property class 8.8. Corrosion behaviour is requires plating (zinc) for corrosion 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 workhorse medium-carbon alloy class for structural joints.
- Grade
- ISO 898-1 property class 8.8
- Corrosion resistance
- Requires plating (zinc) for corrosion 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.
Material specification page for 12-point flange screws in Property Class 8.8 Steel. Covers the grade designation (ISO 898-1 property class 8.8), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to ASME B18.2.3.11M.
Why Choose Property Class 8.8 Steel for 12-Point Flange Screws
The workhorse medium-carbon alloy class for structural joints. For 12-point flange screws, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 8.8 |
|---|
| Magnetic response | Magnetic |
|---|
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
|---|
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
|---|
Corrosion Behavior in Service
Carbon and alloy steel 12-point flange 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 12-Point Flange Screws, class 10.9 or 12.9 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 12-Point Flange Screws Available in Property Class 8.8 Steel
| Thread size | Pitch (mm) | Wrenching size across corners (mm) | Flange diameter dc (mm) | Head height k (mm) | Common length range (mm) | Property class | Reference standard |
|---|
| M6 | 1.0 | 9.0 | 13.0 | 5.4 | 16~60 | 10.9 / 12.9 | ASME B18.2.3.11M |
| M8 | 1.25 | 11.0 | 16.6 | 7.2 | 20~80 | 10.9 / 12.9 | ASME B18.2.3.11M |
| M10 | 1.5 | 13.0 | 20.5 | 9.0 | 25~100 | 10.9 / 12.9 | ASME B18.2.3.11M |
| M12 | 1.75 | 16.0 | 24.4 | 10.8 | 30~120 | 10.9 / 12.9 | ASME B18.2.3.11M |
| M14 | 2.0 | 18.0 | 28.0 | 12.6 | 35~140 | 10.9 / 12.9 | ASME B18.2.3.11M |
| M16 | 2.0 | 21.0 | 32.2 | 14.4 | 40~160 | 10.9 / 12.9 | ASME B18.2.3.11M |
| M20 | 2.5 | 27.0 | 40.0 | 18.0 | 50~200 | 10.9 / 12.9 | ASME B18.2.3.11M |
Dimensions are independent of the material: every size above is available in Property Class 8.8 Steel.
Custom manufacturing · Made to drawing
Need this bolt in a grade that is not listed?
Grade 8 8 Steel is one of the grades the catalog describes. Lengths and thread lengths outside the standard table are the commonest request, followed by a drive the standard does not offer and a head marked with your own part number. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom bolt manufacturingSend a drawing
Applications & Industries
Where 12-Point Flange Screws are used, and what decides the specification in each case. Stocked from M6 to M20.
Industries that specify 12-Point Flange Screws
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Engine & powertrain
Connecting-rod, main-bearing and flywheel bolts torqued in a confined recess.
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Motorsport & performance
High-preload joints where a socket must enter at a shallow angle.
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Hydraulic & press equipment
Cylinder heads and tie rods at class 12.9.
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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.
Typical applications
- high-preload joints in a counterbore a hex socket cannot reach
- twelve engagement points give access every 30°, not every 60°
- integral flange replaces the washer under the head
- 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 12-Point Flange Screws are used, how to specify them, and the cases they are wrong for
