Property Class 8.8 Steel Oval-Head Machine 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.
Property Class 8.8 Steel Oval-Head Machine Screws are supplied to ASME B18.6.3. The grade provides requires plating (zinc) for corrosion protection and is magnetic; the practical service range is commonly limited to approx. +300 °C; confirm against the coating and the load. Property data, grade comparison and the full size table follow.
Why Choose Property Class 8.8 Steel for Oval-Head Machine Screws
The workhorse medium-carbon alloy class for structural joints. For oval-head machine 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 oval-head machine 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 oval-head machine 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 Oval-Head Machine Screws Available in Property Class 8.8 Steel
| Size example | Length (in) | Drive | Head form | Material options | Reference standard |
|---|
| #8-32 | 2 | Phillips | oval raised countersunk | 18-8 stainless steel / steel | ASME B18.6.3 |
| inch machine-screw sizes | | Phillips | oval raised countersunk | 18-8 stainless steel / steel | ASME B18.6.3 |
Dimensions are independent of the material: every size above is available in Property Class 8.8 Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
Grade 8 8 Steel is one of the grades the catalog describes. Head form and drive can be specified to the assembly rather than to a standard: a larger bearing face, a security drive, or a socket sized for the tool already on the bench. 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
Oval-Head Machine Screws are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from #8-32 to inch machine-screw sizes (nominal diameter).
Industries that specify Oval-Head Machine Screws
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Light fabrication
ASME B18.6.3 sizes fit inch machine-screw joints.
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Visible equipment
Oval heads provide a finished raised profile on covers and trim.
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Instrument panels
Phillips drive supports routine assembly in a low-profile raised seat.
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Appliance housings
Stainless and steel options match the enclosure material.
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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
- selecting steel or 18-8 stainless
- seating a raised oval head on a prepared countersink
- choosing the under-head length for the panel stack
- using a Phillips driver on a visible machine screw
- joints where the property class is stated on the drawing
- clamping two machined faces to a calculated preload
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 an oval head in a flat-bottom counterbore; the raised profile needs its matching seat.
- 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 Oval-Head Machine Screws are used, how to specify them, and the cases they are wrong for
