ASTM F912 Alloy Steel Socket Set Screws
The socket set screw specification: alloy steel through hardened to 45 to 53 HRC, torque tested rather than tensile tested, with cup, flat, cone, oval and half-dog points — black oxide finished.
What F912 is.
ASTM F912 covers socket set screws in alloy steel, hardened to 45 to 53 HRC so that the point bites into a shaft and holds. Because a set screw carries torque rather than tension, the specification is written around a torsional strength test by size, from 1.1 in·lbf at #0 to 38 000 in·lbf at 2 in., and around point geometry: cup, flat, cone, oval and half dog. Dimensions are per ASME B18.3.
We machine F912 set screws in special lengths, points and threads from certified alloy bar, heat treated and black oxided, and can supply them with nylon patches or pellets for vibration service.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | 0.30 | 0.48 |
| Phosphorus | P | — | 0.035 |
| Sulfur | S | — | 0.040 |
| Alloying elements | — | required | — |
Values per ASTM F912-11 Table 1 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
Mechanical properties.
| Nominal size | Test torque, min (in·lbf) | Hardness | — | — | — |
|---|---|---|---|---|---|
| #4 (0.112 in.) | 6.0 | 45–53 HRC | |||
| #10 (0.190 in.) | 40 | 45–53 HRC | |||
| ¼ in. | 94 | 45–53 HRC | |||
| ⅜ in. | 317 | 45–53 HRC | |||
| ½ in. | 750 | 45–53 HRC | |||
| ¾ in. | 2 520 | 45–53 HRC | |||
| 1 in. | 8 000 | 45–53 HRC | |||
| 1½ in. | 18 100 | 45–53 HRC | |||
| 2 in. | 38 000 | 45–53 HRC |
Values per ASTM F912-11 Table 2 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. The full table runs from #0 to 2 in.; shortest lengths subject to torque testing depend on the point style.
Specifications that apply.
How F912 ships from Houston.
- Hex and heavy hex bolts and cap screws
- Studs and threaded rod
- Nuts and washers to match
- Machined specials to drawing
F912 fasteners we make.
Every item is manufactured to your drawing or standard in F912, imperial or metric, with an EN 10204 3.1 certificate.
How set screws are specified
A set screw does its job by pressing a hardened point into a shaft, so the specification tests what matters: hardness of the point and the torque the screw can take without the socket stripping or the screw twisting off. F912 sets 45 to 53 HRC and a minimum test torque for every size. Point style sets the holding power and the damage to the shaft: cup points bite hardest, flat points protect the shaft, cone points seat in a drilled hole, and half-dog points locate in a slot or groove.
Testing, certification and marking
- Hardness and torsional strength per lot
- Manufacturer's identification on the package; screws are not individually marked
- Certificate of conformance or test report with heat number
ASTM F880 Stainless Steel Socket Set Screws
The stainless socket set screw specification: 303, 304, 316 and related austenitic grades in annealed or cold-worked condition, torque tested by size, passivated — for shafts and collars in corrosive and food service.
ASTM A574 · ASME B18.3ASTM A574 Alloy Steel Socket Head Cap Screws (170–180 ksi)
The socket head cap screw specification: alloy steel quenched and tempered to 180 ksi in ½ in. and smaller and 170 ksi above, 37 to 44 HRC, black oxide — the standard for tooling, machinery and die work.
ASTM F835 · ASME B18.3ASTM F835 Alloy Steel Socket Button and Flat Head Cap Screws
The low-head socket screws: button and flat countersunk heads in alloy steel at 144 ksi (½ in. and smaller) and 136 ksi above, 37 to 44 HRC — rated below A574 because the shallow head, not the shank, limits the load.