SS 321 Machine ScrewUNS S32100 · ASME B18.6.3 · Manufacturer, trader & exporter, India
AISI 321 · UNS S32100
An SS 321 machine screw is a small-diameter screw for equipment assembly. Finished fastener specification not asserted; UNS S32100 material — requirements to the purchase specification or project drawing. Machine screws assemble instruments, panels and equipment. Pan, countersunk and cheese heads.
- UNS S32100
- ASME B18.6.3
- 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 Machine Screw?
- What it is
- A small-diameter screw for equipment assembly
- Finished spec
- Not asserted
- Material / feedstock
- UNS S32100 material; product form to the purchase specification
- Dimensions
- ASME B18.6.3 · DIN 84 / 963 (legacy DIN)
- Grade
- SS 321 · UNS S32100
- Best at
- High-temperature service between 425 and 815 °C
SS 321 Machine Screw Specification
| Product | SS 321 Machine Screw |
|---|---|
| Finished fastener specification | Not asserted |
| Material / feedstock specification | UNS S32100 material; product form to the purchase specification |
| Dimensional standard | ASME B18.6.3 · DIN 84 / 963 (legacy DIN) |
| Manufacturing route | Route dependent on product design 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 Machine Screw
Machine screws assemble instruments, panels and equipment. Pan, countersunk and cheese heads.
- Pan, flat and cheese heads
- Slotted or Phillips
- M2 – M10 typical
More on choosing: Machine screw guide.
SS 321 Machine Screw: Why 321 for machine screws
Machine screws assemble instruments, panels and equipment. Pan, countersunk and cheese heads. 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 Machine 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 Machine 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.
Standards on this page
Other SS 321 fasteners
SS 321 Machine Screw — questions buyers ask
What sizes are machine screws?
Usually small diameters, M2 to M10 or #2 to 3/8".
What nut is used with SS 321 machine screws?
ASTM A194 8T heavy hex nuts.
Which standard covers SS 321 machine screws?
Finished fastener specification: Not asserted. Material / feedstock: UNS S32100 material; product form to the purchase specification. Dimensions: ASME B18.6.3 · DIN 84 / 963 (legacy DIN). State the finished specification, material and dimensions on your purchase order or project drawing.
What decides the price of a SS 321 machine 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