Quenched & Tempered Alloy Steel Socket Set Screws
ASTM F912 specification covers the requirements for quenched and tempered alloy steel socket-set screws (SSS) in nominal diameters #0 through 2 inch in imperial and M1.6 to M48 in metric series having hardnesses 45 to 53 HRC. These set screws are intended for compression applications only and are not customarily subjected to embrittlement tests. The screws shall be fabricated from alloy steel made to fine grain practice. In the event of controversy over grain size, referee tests on finished screws conducted in accordance with Test Methods E112 shall prevail. The screws may be forged, formed, extruded, machined, or ground to meet the dimensional characteristics and performance requirements. Set screws shall be heat treated by quenching in oil from above the transformation temperature and then tempered by reheating to meet the hardness range. Unless otherwise specified, the screws shall be furnished with one of the following standard surfaces as manufactured, at the option of the manufacturer; (1) bright uncoated; (2) thermal black oxide; or (3) chemical black oxide. Hydrogen embrittlement tests shall not be required for screws furnished in these conditions.
| Element | Composition, % | |
|---|---|---|
| Heat Analysis | Product Analysis | |
| C | 0.30 to 0.48 | 0.28 to 0.50 |
| P, max | 0.035 | 0.040 |
| S, max | 0.040 | 0.045 |
| Nominal Size | Shortest Nominal Screw Lengths Subject to Torque Testing for | Test Torque | |||
|---|---|---|---|---|---|
| Cup and Flat Points | Cone and Oval Points | Half Dog Points | in.-lb, min | ||
| 0 | 0.060 | 0.109 | 0.125 | 0.109 | 1.1 |
| 1 | 0.073 | 0.125 | 0.141 | 0.125 | 2.1 |
| 2 | 0.086 | 0.125 | 0.141 | 0.141 | 2.1 |
| 3 | 0.099 | 0.141 | 0.156 | 0.156 | 6.0 |
| 4 | 0.112 | 0.141 | 0.172 | 0.156 | 6.0 |
| 5 | 0.125 | 0.156 | 0.188 | 0.172 | 11 |
| 6 | 0.138 | 0.172 | 0.203 | 0.188 | 11 |
| 8 | 0.164 | 0.188 | 0.219 | 0.203 | 23 |
| 10 | 0.190 | 0.188 | 0.250 | 0.234 | 40 |
| 1/4 | 0.250 | 0.250 | 0.312 | 0.297 | 94 |
| 5/16 | 0.312 | 0.312 | 0.391 | 0.359 | 183 |
| 3/8 | 0.375 | 0.375 | 0.438 | 0.438 | 317 |
| 7/16 | 0.437 | 0.438 | 0.547 | 0.484 | 502 |
| 1/2 | 0.500 | 0.500 | 0.609 | 0.547 | 750 |
| 5/8 | 0.625 | 0.625 | 0.766 | 0.672 | 1460 |
| 3/4 | 0.750 | 0.750 | 0.906 | 0.797 | 2520 |
| 7/8 | 0.875 | 0.875 | 1.125 | 0.984 | 5750 |
| 1 | 1.000 | 1.000 | 1.266 | 1.125 | 8000 |
| 11/8 | 1.125 | 1.125 | 1.391 | 1.188 | 8000 |
| 11/4 | 1.250 | 1.250 | 1.500 | 1.312 | 11 000 |
| 13/8 | 1.375 | 1.375 | 1.656 | 1.438 | 11 000 |
| 11/2 | 1.500 | 1.500 | 1.797 | 1.562 | 18 100 |
| 13/4 | 1.750 | 1.750 | 2.219 | 1.953 | 38 000 |
| 2 | 2.000 | 2.000 | 2.391 | 2.078 | 38 000 |
Product Shall be Marked with our manufacturing trade mark "TorqBolt" or "TB" along with the designated Grade.
Grade and manufacturer’s identification symbols shall be applied to one end of studs and to the heads of bolts and screws of all sizes. (If the available area is inadequate, the grade symbol may be marked on one end and the manufacturer’s identification symbol marked on the other end.) For bolts and screws smaller than 1⁄4 in. [6 mm] in diameter and studs smaller than 3⁄8 in. [10 mm] in diameter and for 1⁄4 in. [6 mm] in diameter studs requiring more than a total of three symbols, the marking shall be a matter of agreement between the purchaser and the manufacturer.
B18.3 Socket Cap, Shoulder and Set Screw, Inch Series
A751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel Products
E3 Guide for Preparation of Metallographic Specimens
E112 Test Methods for Determining Average Grain Size
E384 Test Method for Microindentation Hardness of Materials
F606/F606M Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets
F2328 Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts, Screws, Studs, and Nuts