Property Class 8.8 Steel Slotted Oval Head Machine Screws, UNC 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 Slotted Oval Head Machine Screws, UNC
The workhorse medium-carbon alloy class for structural joints. For slotted oval head machine screws, unc, 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 slotted oval head machine screws, unc 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 slotted oval head machine screws, unc 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 Slotted Oval Head Machine Screws, UNC Available in Property Class 8.8 Steel
| Size | Pitch P (mm) | Head diameter dk (mm) | A_mean (mm) | Head height k (mm) | C (mm) | J_min (mm) | T_mean (mm) | Length range l (in) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|
| #0 | 0.318 | 2.845 | 2.642 | 0.889 | 0.533 | 0.406 | 0.699 | 1/16"~1 1/2" | ASME B18.6.3 |
| #1 | 0.397 | 3.48 | 3.264 | 1.092 | 0.635 | 0.483 | 0.876 | 1/16"~1 1/2" | ASME B18.6.3 |
| #2 | 0.454 | 4.115 | 3.886 | 1.295 | 0.737 | 0.584 | 1.041 | 1/16"~2 1/2" | ASME B18.6.3 |
| #3 | 0.529 | 4.75 | 4.496 | 1.499 | 0.838 | 0.686 | 1.206 | 1/8"~2 1/2" | ASME B18.6.3 |
| #4 | 0.635 | 5.385 | 5.118 | 1.702 | 0.94 | 0.787 | 1.372 | 1/8"~4" | ASME B18.6.3 |
| #5 | 0.635 | 6.02 | 5.74 | 1.905 | 1.041 | 0.889 | 1.549 | 3/16"~4" | ASME B18.6.3 |
| #6 | 0.794 | 6.655 | 6.35 | 2.108 | 1.143 | 0.991 | 1.702 | 1/8"~4" | ASME B18.6.3 |
| #8 | 0.794 | 7.925 | 7.582 | 2.54 | 1.321 | 1.143 | 2.032 | 1/8"~5" | ASME B18.6.3 |
| #10 | 1.058 | 9.195 | 8.826 | 2.946 | 1.524 | 1.27 | 2.375 | 3/16"~8" | ASME B18.6.3 |
| #12 | 1.058 | 10.465 | 10.058 | 3.353 | 1.727 | 1.422 | 2.705 | 1/4"~8" | ASME B18.6.3 |
| 1/4" | 1.27 | 12.116 | 11.671 | 3.886 | 2.007 | 1.626 | 3.15 | 3/8"~10" | ASME B18.6.3 |
| 5/16" | 1.411 | 15.164 | 14.643 | 4.851 | 2.515 | 1.829 | 3.962 | 1/2"~10" | ASME B18.6.3 |
| 3/8" | 1.587 | 18.212 | 17.615 | 5.842 | 2.972 | 2.057 | 4.775 | 1/2"~12" | ASME B18.6.3 |
| 7/16" | 1.814 | 19.304 | 18.733 | 5.664 | 3.099 | 2.057 | 4.877 | 3/4"~12" | ASME B18.6.3 |
| 1/2" | 1.954 | 20.701 | 20.066 | 5.664 | 3.327 | 2.311 | 4.978 | 3/4"~12" | ASME B18.6.3 |
| 9/16" | 2.117 | 23.673 | 22.987 | 6.604 | 3.81 | 2.591 | 5.804 | 3/4"~12" | ASME B18.6.3 |
| 5/8" | 2.309 | 26.67 | 25.908 | 7.569 | 4.293 | 2.946 | 6.604 | 3/4"~14" | ASME B18.6.3 |
| 3/4" | 2.54 | 32.639 | 31.75 | 9.449 | 5.232 | 3.327 | 8.204 | 1"~14" | 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. 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.
