SS 321 Socket Head Cap ScrewASTM A193 · ASME B18.3 · Manufacturer, trader & exporter, India
AISI 321 · UNS S32100
An SS 321 socket head cap screw is a screw with a cylindrical head and hexagon socket. ASTM A193 B8T where specified; confirm grade and class in the purchase specification. Allen-type cap screws are used where the head must sit flush or space is tight.
- ASTM A193
- ASME B18.3
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 321 Socket Head Cap Screw?
- What it is
- A screw with a cylindrical head and hexagon socket
- Finished spec
- ASTM A193 B8T where specified
- Material / feedstock
- Within the finished specification (A193 B8T)
- Dimensions
- ASME B18.3 · ISO 4762 · DIN 912 (legacy DIN)
- Grade
- SS 321 · UNS S32100
- Best at
- High-temperature service between 425 and 815 °C
SS 321 Socket Head Cap Screw Specification
| Product | SS 321 Socket Head Cap Screw |
|---|---|
| Finished fastener specification | ASTM A193 B8T where specified |
| Material / feedstock specification | Within the finished specification (A193 B8T) |
| Dimensional standard | ASME B18.3 · ISO 4762 · DIN 912 (legacy DIN) |
| Manufacturing route | To the finished specification and purchase specification |
| Project / purchase specification | Yes — finished fastener requirements are to the purchase specification or project drawing |
| Sizes | M10 – M64 · ½" – 4" (others on request) |
| Threads | UNC · UN-8 · metric coarse |
| Testing | PMI (as specified in the PO) · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 or 3.2 on request / as specified in the PO |
When to Choose a Socket Head Cap Screw
Allen-type cap screws are used where the head must sit flush or space is tight.
- Hex socket drive
- ASME B18.3 · DIN 912
- Metric and inch
More on choosing: Socket head cap screw guide.
SS 321 Socket Head Cap Screw: Why 321 for socket head cap screws
Allen-type cap screws are used where the head must sit flush or space is tight. In SS 321, the choice usually comes down to the medium and temperature — the rows here are the points buyers check for this exact combination.
| Why this grade | Stainless fasteners resist atmospheric and process corrosion. SS 321 is picked for high-temperature service between 425 and 815 °C. |
|---|---|
| Typical service | Aircraft exhaust — Manifolds, bellows and exhaust systems. |
| Bolting | ASTM A193 B8T studs with A194 8T nuts |
SS 321 Socket Head Cap Screw Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Titanium | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Nitrogen | As specified |
| Phosphorus | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS S32100.
SS 321 Socket Head Cap Screw Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A240 for UNS S32100 — Annealed plate & sheet.
Full chemistry, properties and equivalents are on the SS 321 grade page.
Other SS 321 fasteners
SS 321 Socket Head Cap Screw — questions buyers ask
DIN 912 and ISO 4762 — are they the same?
Yes, ISO 4762 replaced DIN 912 with the same main dimensions.
What nut is used with SS 321 socket head cap screws?
ASTM A194 8T heavy hex nuts.
Which standard covers SS 321 socket head cap screws?
Finished fastener specification: ASTM A193 B8T where specified. Material / feedstock: Within the finished specification (A193 B8T). Dimensions: ASME B18.3 · ISO 4762 · DIN 912 (legacy DIN). State the finished specification, material and dimensions on your purchase order or project drawing.
What decides the price of a SS 321 socket head cap screw?
The alloy price, the size and dimensions, quantity, and the testing and documents required. Send your list and we quote the same working day.
What documents do you supply?
EN 10204 3.1 or 3.2 certificates available on request / as specified in the PO; dimensional reports as required. PMI can be arranged depending on product and requirements, as specified in the PO.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026