ASTM A574 Socket Head Cap Screws
ASTM A574 socket head cap screws are high-strength alloy steel fasteners with a hexagon socket drive, designed for applications requiring reliable clamping force and compact installation. The screws are manufactured with a cylindrical head and recessed hexagonal socket, allowing them to be installed where space around the fastener is limited.
At Ningbo Teng Qi Fasteners, we manufacture and supply ASTM A574 socket head cap screws in alloy steel with controlled dimensions, thread accuracy, heat treatment, and mechanical properties. Our production includes multi-station cold heading, thread rolling, heat treatment, and precision inspection to maintain consistent quality from forming to finished threads. Screws can be supplied according to ASTM A574 requirements and customer drawings, with different sizes, lengths, finishes, and packaging options available.
Material Chemical Composition:
ASTM A574 socket head cap screws are manufactured from alloy steel selected to meet the material and chemical composition requirements of the specification. The chemical composition controls the basic characteristics of the steel and provides a suitable foundation for achieving the required mechanical properties after heat treatment.
| Grade Designation | 4137 | 4142 | 4145 | 4340 | 8740 | 5137M | 51B37M |
|---|---|---|---|---|---|---|---|
| Carbon | 0.33–0.42 | 0.38–0.47 | 0.41–0.50 | 0.36–0.45 | 0.36–0.45 | 0.33–0.42 | 0.31–0.42 |
| Manganese | 0.67–0.93 | 0.71–1.04 | 0.71–1.04 | 0.57–0.83 | 0.71–1.04 | 0.27–0.53 | 0.27–0.53 |
| Phosphorus | 0.040 | 0.040 | 0.040 | 0.040 | 0.040 | 0.040 | 0.040 |
| Sulfur | 0.045 | 0.045 | 0.045 | 0.045 | 0.045 | 0.045 | 0.045 |
| Silicon | 0.13–0.37 | 0.13–0.37 | 0.13–0.37 | 0.13–0.37 | 0.13–0.37 | 0.13–0.37 | 0.13–0.37 |
| Nickel | … | … | … | 1.65–2.05 | 0.37–0.73 | … | … |
| Chromium | 0.75–1.15 | 0.75–1.15 | 0.75–1.15 | 0.67–0.93 | 0.37–0.63 | 0.85–1.25 | 0.90–1.30 |
| Molybdenum | 0.13–0.27 | 0.13–0.27 | 0.13–0.27 | 0.18–0.32 | 0.18–0.32 | … | … |
| Boron | … | … | … | … | … | … | B |
Mechanical Property:
ASTM A574 socket head cap screws are heat treated to achieve the high strength and hardness required for demanding fastening applications. The specification establishes mechanical property requirements for the finished screws, including tensile strength, hardness, and torsional performance. These requirements help ensure that the screws can withstand high clamping loads and resist failure during installation and service.
Our ASTM A574 socket head cap screws are heat treated under controlled conditions, with mechanical properties checked according to the applicable requirements of the specification. Depending on the order requirements, testing and inspection can include hardness testing, tensile testing, and torsional testing. The mechanical property requirements are summarized in the table below.
| Property | ≤0.5 in. Nom. Dia. | >0.5 in. and < 1.0 in. Nom. Dia. | ≥1.0 in. Nom. Dia. |
|---|---|---|---|
| Tensile strength | 180 | 170 | 170 |
| Proof load (stress), ksi | 140 | 135 | 135 |
| Hardness: (HRC) | 39–44 | 37–44 | 37–44 |
Tension Requirement for Coarse Thread :
| Screw Dia (D), in. | Threads/in. | Tensile Load, min, lbf A | Stress Area, in.² B | Proof Load, min, lbf C |
|---|---|---|---|---|
| 0.073 | 64 | 473 | 0.00263 | 368 |
| 0.086 | 56 | 666 | 0.00370 | 518 |
| 0.099 | 48 | 877 | 0.00487 | 682 |
| 0.112 | 40 | 1090 | 0.00604 | 846 |
| 0.125 | 40 | 1430 | 0.00796 | 1110 |
| 0.138 | 32 | 1640 | 0.00909 | 1270 |
| 0.164 | 32 | 2520 | 0.0140 | 1960 |
| 0.190 | 24 | 3150 | 0.0175 | 2450 |
| 0.216 | 24 | 4350 | 0.0242 | 3380 |
| 0.250 | 20 | 5730 | 0.0318 | 4450 |
| 0.3125 | 18 | 9440 | 0.0524 | 7340 |
| 0.375 | 16 | 13900 | 0.0775 | 10800 |
| 0.4375 | 14 | 19100 | 0.1063 | 14900 |
| 0.500 | 13 | 25500 | 0.1419 | 19900 |
| 0.5625 | 12 | 30900 | 0.182 | 24600 |
| 0.625 | 11 | 38400 | 0.226 | 30500 |
| 0.750 | 10 | 56800 | 0.334 | 45100 |
| 0.875 | 9 | 78500 | 0.462 | 62400 |
| 1.000 | 8 | 103000 | 0.606 | 81800 |
| 1.125 | 7 | 129000 | 0.763 | 103000 |
| 1.250 | 7 | 165000 | 0.969 | 131000 |
| 1.375 | 6 | 196000 | 1.155 | 156000 |
| 1.500 | 6 | 239000 | 1.405 | 190000 |
| 1.750 | 5 | 323000 | 1.90 | 256000 |
| 2.000 | 4½ | 425000 | 2.50 | 338000 |
| 2.250 | 4½ | 552000 | 3.25 | 439000 |
| 2.500 | 4 | 680000 | 4.00 | 540000 |
| 2.750 | 4 | 838000 | 4.93 | 666000 |
| 3.000 | 4 | 1010000 | 5.97 | 806000 |
| 3.250 | 4 | 1210000 | 7.10 | 958000 |
| 3.500 | 4 | 1420000 | 8.33 | 1120000 |
| 3.750 | 4 | 1640000 | 9.66 | 1300000 |
| 4.000 | 4 | 1880000 | 11.08 | 1500000 |
Tension Requirement for Fine Thread：
| Screw Dia (D), in. | Threads/in. | Tensile Load, min, lbf A | Stress Area, in.² B | Proof Load , min, lbf C |
|---|---|---|---|---|
| 0.060 | 80 | 324 | 0.00180 | 252 |
| 0.073 | 72 | 500 | 0.00278 | 389 |
| 0.086 | 64 | 709 | 0.00394 | 552 |
| 0.099 | 56 | 941 | 0.00523 | 732 |
| 0.112 | 48 | 1190 | 0.00661 | 925 |
| 0.125 | 44 | 1490 | 0.00830 | 1160 |
| 0.138 | 40 | 1830 | 0.01015 | 1420 |
| 0.164 | 36 | 2650 | 0.01474 | 2060 |
| 0.190 | 32 | 3600 | 0.0200 | 2800 |
| 0.250 | 28 | 6500 | 0.0364 | 5100 |
| 0.216 | 28 | 4600 | 0.0258 | 3600 |
| 0.3125 | 24 | 10400 | 0.0580 | 8120 |
| 0.375 | 24 | 15800 | 0.0878 | 12300 |
| 0.4375 | 20 | 21400 | 0.1187 | 16600 |
| 0.500 | 20 | 28800 | 0.1599 | 22400 |
| 0.5625 | 18 | 34500 | 0.203 | 27400 |
| 0.625 | 18 | 43500 | 0.256 | 34600 |
| 0.750 | 16 | 63400 | 0.373 | 50600 |
| 0.875 | 14 | 86500 | 0.509 | 68700 |
| 1.000 | 12 | 113000 | 0.663 | 89500 |
| 1.125 | 12 | 146000 | 0.856 | 116000 |
| 1.250 | 12 | 182000 | 1.073 | 145000 |
| 1.375 | 12 | 224000 | 1.315 | 178000 |
| 1.500 | 12 | 269000 | 1.581 | 213000 |
| 2.000 | 4½ | 425000 | 2.50 | 338000 |
| 2.250 | 4½ | 552000 | 3.25 | 439000 |
| 2.500 | 4 | 680000 | 4.00 | 540000 |
| 2.750 | 4 | 838000 | 4.93 | 666000 |
| 3.000 | 4 | 1010000 | 5.97 | 806000 |
| 3.250 | 4 | 1210000 | 7.10 | 958000 |
| 3.500 | 4 | 1420000 | 8.33 | 1120000 |
| 3.750 | 4 | 1640000 | 9.66 | 1300000 |
| 4.000 | 4 | 1880000 | 11.08 | 1500000 |