OEM manufacturer ASME B18.3 · ISO 4762 · DIN 912 · ASTM A574 · ASTM F837
Socket Head Cap Screws (Allen Bolts) — ASME B18.3 & ISO 4762
Socket head cap screws, also called Allen bolts, are cylindrical-head screws driven by a hexagon key in a recessed socket. Teshi Group manufactures them to ASME B18.3 and ISO 4762 / DIN 912 in high-strength alloy steel and stainless steel.
Also called: Allen bolts, Allen cap screws, SHCS, DIN 912 bolts, socket cap screws, hex socket bolts
What are Socket Head Cap Screws?
A socket head cap screw has a round, upright head with an internal hexagon socket. Because the tool works inside the head, the screw can sit in a counterbore or in tight spaces where a spanner will not fit, leaving a flush surface. Alloy steel versions are through-hardened to high strength, so a smaller screw can carry the same load as a larger hex bolt. They are used in machinery, valve actuators, instrument fittings and dies, where compact, high-strength fastening is needed.
Key features
- Inch sizes to ASME B18.3; metric to ISO 4762 / DIN 912
- Alloy steel to ASTM A574 and ISO 898-1 property class 12.9
- Stainless steel to ASTM F837 and ISO 3506 A2-70 / A4-70 / A4-80
- Black oxide, zinc or plain finish
- Low-head and button/flat head socket screws on request
Specification
| Supply | OEM manufacturer — Teshi Group, India |
|---|---|
| Standard | ASME B18.3 (inch), ISO 4762 / DIN 912 (metric) |
| Grades — carbon steel | ASTM A307 Gr A / B, ASTM A563 nuts, SAE J429 Gr 2 / 5 / 8, ISO 898-1 class 4.6, 5.6, 8.8, 10.9, 12.9; ASTM F3125 (A325, A490) |
| Grades — alloy steel | ASTM A193 B7, B7M, B16; nuts ASTM A194 2H, 2HM, 3, 7, 7M, 16 |
| Grades — low-temperature | ASTM A320 L7, L7M, L43; nuts ASTM A194 7 / 7M with S3 impact test |
| Grades — high-temperature | ASTM A453 Gr 660 (A286, UNS S66286); ASTM A193 B16 |
| Grades — stainless steel | ASTM A193 / A320 B8, B8M, B8T, B8C (Class 1 and Class 2); nuts ASTM A194 8, 8M, 8T, 8C, 8F; ISO 3506 A2-70, A4-70, A4-80; ASTM F593 / F594 |
| Grades — 904L and 6Mo | 904L (UNS N08904), 254 SMO / 6Mo (UNS S31254) |
| Grades — duplex and super duplex | Duplex UNS S31803 / S32205 and super duplex UNS S32750 / S32760 (ASTM A1082 bolting, A276 / A479 bar) |
| Grades — nickel alloys | Monel 400 (ASTM B164, N04400), Monel K-500 (B865, N05500), Inconel 600 (B166, N06600), Inconel 625 (B446, N06625), Inconel 718 (B637, N07718), Incoloy 825 (B425, N08825), Hastelloy C276 (B574, N10276), Alloy 20 (B473, N08020) |
| Grades — titanium | ASTM B348 Grade 1, 2, 5 (Ti-6Al-4V), 7, 12 |
| Grades — copper-nickel | Cu-Ni 90/10 (C70600) and 70/30 (C71500) against order |
| Grade availability | Every grade listed is made or supplied against order, with EN 10204 3.1 certificates (3.2 / third-party inspection when specified) and PMI on alloy, stainless, duplex and nickel grades. |
| Drive | Internal hexagon socket |
| Threads | UNC / UNF class 3A; ISO metric coarse and fine |
| Finish | Black oxide (thermal), zinc electroplated, plain |
| Testing | Tensile, hardness, proof load; PMI on stainless |
| Documents | EN 10204 3.1 mill test certificate (3.2 / third-party inspection when specified), dimensional inspection report |
Applications
- Valve actuator and gearbox mounting
- Machinery, jigs and dies
- Instrument and control panels
- Pump and compressor assemblies
- Counterbored joints needing flush heads
FAQ
Socket Head Cap Screws: common questions
Is an Allen bolt the same as a socket head cap screw?
Yes. Allen bolt is the trade name commonly used in India and elsewhere for a socket head cap screw, after the Allen key used to drive it.
What is DIN 912?
DIN 912 is the German standard for metric socket head cap screws. It has been replaced by ISO 4762, which has the same basic dimensions, and both designations are still used on orders.
What strength is a 12.9 socket cap screw?
Property class 12.9 under ISO 898-1 means nominal tensile strength of 1200 MPa with a yield-to-tensile ratio of 0.9. It is the usual grade for alloy steel socket cap screws.
Are stainless socket head cap screws as strong as alloy steel?
No. Stainless A2-70 or A4-80 socket screws have lower tensile strength than class 12.9 alloy steel screws, but they resist corrosion. Choose the grade by the joint load and the service environment.
Need a size or grade not listed here?
Our engineering team manufactures against your drawing or datasheet, with dimensional sign-off before dispatch.
Send us your specificationTraceability
From mill heat to your site
- 01
Approved mill material
Received against the mill certificate; heat number registered.
- 02
Forging & machining
Heat number carried through every stage in our Indian works.
- 03
PMI, dimensional & NDT
Every lot inspected to the governing standard; TPI witness on request.
- 04
Stamped & certified dispatch
Hard-stamped pieces with EN 10204 3.1 / 3.2 certificates.
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