SS 304 FastenersASTM A193 B8 · Manufacturer, stockist & exporter, India
Also sold as AISI 304 · UNS S30400 · W.Nr 1.4301 · 18/8 stainless
SS 304 fasteners — stud bolts, hex bolts, nuts and washers — are made from ASTM A193 B8 · A194 8 bar stock to ASME B18 dimensions. It is a austenitic chromium-nickel stainless steel, chosen for general corrosion resistance, food, water and architectural work. Kanak Steel & Engineering Co. supplies it with EN 10204 3.1 mill certificates from Mumbai to buyers across India, the Gulf, South-East Asia, South America, Europe, the UK and the USA.
- Stock & mill supply
- EN 10204 3.1 / 3.2
- PMI on every heat
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is SS 304 Fasteners?
SS 304 fasteners is an austenitic chromium-nickel stainless steel supplied as fasteners to ASTM A193 B8 (UNS S30400). Buyers specify it for general corrosion resistance, food, water and architectural work. It is also sold as AISI 304, UNS S30400, W.Nr 1.4301.
- What it is
- Austenitic chromium-nickel stainless steel
- Bar stock
- ASTM A193 B8 · A194 8
- Dimensions
- ASME B18.2.1 · B18.2.2 · B18.31.2
- Threads
- UNC · UN-8 · metric
- Sizes
- M10 – M64 · ½" – 4"
- Best at
- General corrosion resistance, food, water and architectural work
SS 304 Fasteners Specification & Sizes
| Material | ASTM A193 B8 · A194 8 |
|---|---|
| Dimensional standards | ASME B18.2.1 (bolts) · B18.2.2 (nuts) · B18.31.2 (studs) · DIN 931 / 933 / 934 |
| Types | Stud bolt · Hex bolt · Heavy hex nut · Hex nut · Washer · Threaded rod · U-bolt · Eye bolt · Anchor bolt · Foundation bolt · Socket head cap screw · Machine screw |
| Threads | UNC, UN-8 and metric coarse |
| Coating | Plain · PTFE on request |
| Documents | EN 10204 3.1 |
SS 304 Stud Bolts: Grade & Nut Pairing
Pressure bolting in this material is ASTM A193 B8 studs with ASTM A194 8 heavy hex nuts. A193 B8-series bolting comes in Class 1 (carbide solution treated) and Class 2 (strain hardened, higher strength) — state the class.
Torque (T = K × F × d), stud length and coatings are covered in the fasteners guide.
| Galling | Stainless and nickel-alloy threads gall — always use anti-seize, and avoid high-speed tightening |
|---|---|
| Coatings | Usually supplied plain; PTFE coating on request to ease tightening |
| Marking | Grade symbol and maker's mark on each stud end and nut, as the standard requires |
| Certificates | EN 10204 3.1 for the bar heat; mechanical test reports on the finished bolts on request |
SS 304 Fasteners Chemical Composition
| Element | Weight % |
|---|---|
| Chromium | 17.5 – 19.5 |
| Nickel | 8.0 – 10.5 |
| Carbon | 0.07 max |
| Manganese | 2.00 max |
| Silicon | 0.75 max |
| Nitrogen | 0.10 max |
| Phosphorus | 0.045 max |
| Sulphur | 0.030 max |
| Iron | Balance |
SS 304 Fasteners Mechanical Properties
| Annealed plate & sheet | Value |
|---|---|
| Tensile strength | 515 MPa · 75 ksi |
| Yield strength 0.2% | 205 MPa · 30 ksi |
| Elongation | 40% |
| Hardness | 201 HB max |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8 g/cm³ |
| Melting range | 1400 – 1450 °C |
| Magnetic | Non-magnetic annealed; slightly magnetic after cold work |
| PREN (approx.) | ≈ 18 |
SS 304 Equivalent Grades
Values follow ASTM A240 for UNS S30400. Always check against the edition named on your purchase order.
Six-digit Harmonized System heading (iron and steel, chapter 72–73). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify SS 304 Fasteners with PMI
Positive material identification with a handheld XRF gun confirms the alloy on the piece itself, in seconds, before it is cut or welded. SS 304 is most often mixed up with SS 316 / 316L — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen; those come from the mill certificate or optical emission (OES) testing. We PMI-test nickel alloys as standard and any grade on request.
| Element | SS 304 | SS 316 / 316L |
|---|---|---|
| Nickel | 8.0 – 10.5 | 10.0 – 14.0 |
| Chromium | 17.5 – 19.5 | 16.0 – 18.0 |
| Molybdenum | residual | 2.00 – 3.00 |
| Iron | Balance | Balance |
| Manganese | 2.00 max | 2.00 max |
SS 304 fasteners by type
SS 304 Fasteners Applications
SS 304 is specified when the cheaper grade will not survive the service but a higher alloy would be more than the job needs. These are the jobs our buyers use it for.
SS 304 Fasteners vs 316L, 304L and 904L
| Grade | Fasteners standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| SS 304L | ASTM A193 B8 · A194 8 | ≈ 18 | Welded tanks, piping and vessels in general corrosive service |
| SS 304 | ASTM A193 B8 · A194 8 | ≈ 18 | General corrosion resistance, food, water and architectural work |
| SS 316 / 316L | ASTM A193 B8M · A194 8M | ≈ 24 | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 904L | ASTM A479 | ≈ 35 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
SS 304 Corrosion Resistance — Element by Element
Each alloying addition has a job. Knowing which one protects against your medium is the quickest way to judge whether 304 fits.
About 18% chromium forms the passive film that makes the steel stainless.
Nickel keeps the structure austenitic — tough at low temperature and easy to form and weld.
Up to 0.07% carbon: fine for most work, but choose 304L where heavy sections are welded and service is corrosive.
Without molybdenum, 304 pits in chlorides — step up to 316L for coastal or salty service.
How your 304 fasteners order runs
- 01Enquiry review — we confirm size, standard edition and documents against your MR or drawing.
- 02Heat selection & PMI — the mill certificate is checked and material is PMI-tested before processing.
- 03Processing — cutting, machining or bevelling to your specification, with heat numbers marked.
- 04Inspection — your third-party inspector witnesses, or we share photos and test reports.
- 05Packing & dispatch — seaworthy packing from Nhava Sheva (JNPT), Mumbai, FOB or CIF, documents sent before the vessel sails.
Welding & Fabricating SS 304 Fasteners
SS 304 welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ER308 / ER308L (AWS A5.9) |
|---|---|
| Over-alloyed filler | ER309L for dissimilar joints to carbon steel |
| Preheat | Not required; keep interpass temperature low |
| Cutting | Thermal or abrasive cutting; grind off heat-tinted edges before welding |
Follow your approved WPS; this is general guidance. See also 304 fittings and 304 flanges for the matching pipe-system parts.
How to Order SS 304 Fasteners: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Fastener type, size and length
- Thread form
- Material and marking
- Quantity in sets
- Certificate type
- Delivery port and date
SS 304 fasteners for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 304 fasteners — questions buyers ask
Is SS 304 the same as AISI 304?
Yes. AISI 304, UNS S30400, W.Nr 1.4301 all refer to the same material, and fasteners is ordered to ASTM A193 B8 whichever name is on the enquiry.
Why use SS 304 bolts instead of B7 carbon steel?
On SS 304 flanges in corrosive service, carbon-steel bolts corrode first. Matching-alloy bolting avoids galvanic corrosion and bolt failure.
What nut goes with SS 304 stud bolts?
ASTM A194 8 heavy hex nuts.
How do I stop SS 304 bolts galling?
Use an anti-seize compound on threads and nut faces, tighten at moderate speed, and do not reuse galled nuts.
SS 304 or SS 904L — which should I choose?
SS 304 is chosen for general corrosion resistance, food, water and architectural work. SS 904L is the step up when you need more pitting resistance or strength. See the comparison table on this page, or ask us with your process conditions.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026