Quick Snapshot
Sizes: M3–M56 | 3/16"–4" | Length 3–200 mm | Custom sizes on request
Grades: 304, 304L (low carbon), 304H (high temperature)
Standards: ASTM A193/A194, ASME SA193/SA194, DIN 931/933/934, ISO 4014/4032
Certification: EN 10204 3.1 & 3.2 MTC, ISO-approved quality system
Types: Bolts, Nuts, Washers, Screws, Studs, Threaded Rods
The SS 304 fasteners are the most commonly specified grade of austenitic stainless steel fastener due to their excellent corrosion resistance, clean formability, and strong strength at an affordable price, making 304 the most widely specified austenitic fastener grade. These fasteners are made of an 18/8 chromium-nickel alloy (18-20% Cr, 8-10.5% Ni) and have a thin passive layer of self-healing oxide, which protects them from rust, oxidizing acids, and attack by the atmosphere in an almost infinite number of areas. We manufacture and stock an entire range of SS 304 bolts, nuts, washers, screws, and studs, all traceable to raw-material heat numbers with genuine material test certificates. Our 304 fasteners are known for delivering consistent dimensional accuracy, proven mechanical properties, and reliable service life, whether you're bolting a food-processing skid, a chemical dosing line, an architectural facade, or a water-treatment plant. Whether you are sourcing ready stock, custom manufacturing, or ordering with rapid global delivery, with mill-certified traceability and EN 10204 3.1 documentation on every order
Grade 304 stainless steel is an austenitic Cr-Ni alloy known internationally as UNS S30400, WNR 1.4301, JIS SUS 304 and EN X5CrNi18-10. Because it is non-magnetic in the annealed condition (mildly magnetic after cold working), highly ductile, and easy to weld and form, it is the default choice for general-purpose stainless bolting. Unifit Fastener converts this grade into a full catalogue of fastening solutions.
| Parameter | Specification |
|---|---|
| Material Standard | ASTM A193 / A194, ASME SA193 / SA194 |
| Grade / UNS | SS 304, 304L, 304H | UNS S30400 / S30403 / S30409 |
| Werkstoff (WNR) | 1.4301 (304), 1.4306/1.4307 (304L), 1.4948 (304H) |
| Size Range | M3 to M56 | 3/16" to 4" | Custom sizes |
| Length | 3 mm to 200 mm (longer on request) |
| Dimension Standards | DIN 931/933/934, ISO 4014/4017/4032, ASME B18.2.1 |
| Threads Available | Metric, UNC, UNF, BSW, BSF (coarse & fine) |
| Surface Finish | Plain, Passivated, Phosphating, Oxidation, HDG |
| Manufacturing | Cold forging, hot forging, CNC machining, thread rolling |
| Certification | EN 10204 3.1 / 3.2 MTC |
| HSN Code | 73181500 |
| Element | SS 304 | SS 304L | SS 304H |
|---|---|---|---|
| Carbon (C) | 0.08 max | 0.030 max | 0.04–0.10 |
| Manganese (Mn) | 2.00 max | 2.00 max | 2.00 max |
| Silicon (Si) | 0.75 max | 1.00 max | 0.75 max |
| Phosphorus (P) | 0.045 max | 0.045 max | 0.045 max |
| Sulphur (S) | 0.030 max | 0.030 max | 0.030 max |
| Chromium (Cr) | 18.0–20.0 | 18.0–20.0 | 18.0–20.0 |
| Nickel (Ni) | 8.0–10.5 | 8.0–12.0 | 8.0–11.0 |
| Nitrogen (N) | 0.10 max | 0.10 max | 0.10 max |
| Iron (Fe) | Balance | Balance | Balance |
| Property | Value |
|---|---|
| Tensile Strength (min) | 515 MPa (75,000 psi) |
| Yield Strength, 0.2% Proof (min) | 205 MPa (30,000 psi) |
| Elongation (min) | 35–40% in 50 mm |
| Hardness (Rockwell B, max) | 92 HRB |
| Hardness (Brinell, max) | 201 HB |
| Density | 8.0 g/cm³ (7.93–8.00) |
| Melting Point | 1,399–1,454 °C (2,550 °F) |
| Elastic Modulus | 193 GPa |
| Thermal Conductivity (100°C) | 16.2 W/m·K |
| Service Temperature | Up to ~870–925 °C (304H) |
| Grade | UNS | WNR / EN | JIS | BS | AFNOR | GOST |
|---|---|---|---|---|---|---|
| SS 304 | S30400 | 1.4301 | SUS 304 | 304S31 | Z7CN18-09 | 08X18H10 |
| SS 304L | S30403 | 1.4306 / 1.4307 | SUS 304L | 304S11 | Z3CN18-10 | 03X18H11 |
| SS 304H | S30409 | 1.4948 | – | 304S51 | – | – |
| Nominal | Body Dia D (max) | Across Flats F (max) | Across Corners C (max) | Head Thickness H (max) |
|---|---|---|---|---|
| M10 | 10.00 | 17.00 | 18.48 | 6.63 |
| M12 | 12.00 | 19.00 | 20.78 | 7.76 |
| M16 | 16.00 | 24.00 | 27.71 | 10.32 |
| M20 | 20.00 | 30.00 | 34.64 | 12.88 |
| M24 | 24.00 | 36.00 | 41.57 | 15.44 |
| M30 | 30.00 | 46.00 | 53.12 | 19.48 |
| M36 | 36.00 | 55.00 | 63.51 | 23.38 |
| M42 | 42.00 | 65.00 | 75.06 | 26.97 |
| M48 | 48.00 | 75.00 | 86.60 | 31.07 |
| M56 | 56.00 | 85.00 | 98.15 | 36.20 |
| Size | Length (mm) | Size | Length (mm) |
|---|---|---|---|
| M3 | 5–50 | M16 | 16–1000 |
| M4 | 6–70 | M20 | 25–1000 |
| M5 | 6–100 | M24 | 30–1000 |
| M6 | 6–200 | M30 | 40–1500 |
| M8 | 8–300 | M36 | 50–1500 |
| M10 | 10–500 | M42 | 60–1000 |
| M12 | 12–600 | M56 | on request |
| Nut Size | Across Flats (Dia) | Hex Nut Height | Jam Nut Height | Nylock Height |
|---|---|---|---|---|
| M6 | 10 | 5 | 3.2 | 6 |
| M8 | 13 | 6.5 | 4 | 8 |
| M10 | 17 | 8 | 5 | 10 |
| M12 | 19 | 10 | 6 | 12 |
| M14 | 22 | 11 | 7 | 14 |
| M16 | 24 | 13 | 8 | 16 |
| M20 | 30 | 16 | 10 | 20 |
Values are typical dry-torque references — always confirm against your joint design, lubrication and preload requirements.
| Bolt Size | Proof Load Class (BS EN ISO 3506) | Tension Capacity Pnom (kN) | Shear Capacity Psb (kN) |
|---|---|---|---|
| M10 | 70 | 20.9 | 18.0 |
| M12 | 70 | 30.3 | 26.2 |
| M14 | 70 | – | 35.8 |
| M16 | 70 | – | 44.2 |
| M20 | 70 | – | – |
| M27 | 70 | 165.3 | 142.5 |
| M30 | 70 | 202.0 | 174.2 |
| M33 | 70 | 249.9 | 215.5 |
A complete fastening ecosystem under one roof — standard catalogue items and made-to-drawing specials.
WNR 1.4301 Thread Cutting Screws
WNR 1.4301 Hex Head Bolts
UNS S30400 Socket Set Screws
SUS 304 Shoulder Bolts
SUS 304 Self Drilling Screws
SUS 304 Hex Jam Nuts
SUS 304 Flat Washers
Stainless Steel 304 Eye Bolts
SS 304 Stove Nuts
SS 304 Square Washers
SS 304 Hanger Bolts
SS 304 Coupling Nuts
INOX 304 Wood Screws
INOX 304 Wing Nuts
INOX 304 Square Head Bolts
AISI 304 J-Bolts
AISI 304 Fender Washers
304 Stainless Structural Washers
304 stainless steel U-Bolts
304 Stainless Steel Eye Screws
304 stainless Machine Screws
304 Stainless Keps-K Lock Nuts
304 stainless Flange Bolts
304 Stainless Castle Nuts
304 SS Hex Lag Screws
304 SS Heavy Hex Nuts
304 SS Drywall Screws
304 SS Cap Nuts
The corrosion resistance and clean strength of grade 304 make it the go-to fastener for industries where reliability and hygiene matter.
| Industry | Typical Use |
|---|---|
| Construction & Architecture | Structural connections, facades, railings, cladding |
| Chemical & Petrochemical | Dosing lines, skids, piping supports, process equipment |
| Food, Beverage & Dairy | Hygienic equipment, conveyors, tanks, wash-down zones |
| Water Treatment & Plumbing | Pumps, valves, filtration frames, potable-water systems |
| Pharma & Biotech | Clean-room assemblies, reactors, instrumentation |
| Automotive & Transport | Trim, brackets, exhaust-adjacent hardware |
| Power & Electrical | Panels, enclosures, switchgear, solar mounting |
| Marine & Coastal | Above-water hardware, deck fittings, splash-zone brackets |
| Criterion | SS 304 | SS 304L | SS 304H |
|---|---|---|---|
| Carbon Content | ≤0.08% | ≤0.03% (low) | 0.04–0.10% (high) |
| Best For | General service | Welded assemblies | High-temperature service |
| Corrosion in Welds | Good | Excellent (no sensitisation) | Good |
| High-Temp Strength | Standard | Lower | Superior (to ~870–925°C) |
| Typical Use | All-round bolting | Chemical / marine welds | Boilers, exchangers |
Quick rule: choose 304L when welding or fighting chloride/acid corrosion, 304H for heat, and standard 304 for everything else.
Every batch undergoes destructive and non-destructive checks before dispatch:
| Test | Purpose |
|---|---|
| Spectro / Chemical Analysis (PMI) | Confirms 304 chemistry & grade identity |
| Intergranular Corrosion (IGC) Test | Verifies resistance to sensitisation |
| Pitting Resistance Test | Assesses chloride-corrosion durability |
| Hardness Test | Confirms mechanical condition |
| Dye Penetrant (DP) Test | Detects surface flaws |
| Tensile / Proof-Load Test | Validates strength ratings |
| Micro & Flaring Test | Checks microstructure and ductility |
SS 304 fastener pricing is quoted per kilogram or per piece and depends on grade, size, quantity, finish, and current nickel/chromium pricing. Share your BOM for an accurate, same-day quotation.
| Item | Indicative Basis |
|---|---|
| SS 304 Hex Bolt | Quoted per kg / per piece (FOB) on request |
| SS 304 Hex Nut | Quoted per kg / per piece (FOB) on request |
| SS 304 Washer | Quoted per kg / per piece (FOB) on request |
| SS 304 Stud Bolt | Quoted per kg / per piece (FOB) on request |
| SS 304 Screw | Quoted per kg / per piece (FOB) on request |
Value-adds: small-quantity orders, custom manufacturing, hard-to-find items, and international sourcing — with ready stock for fast dispatch across the Middle East, Europe, Asia, Africa and the Americas.
The key difference is carbon content. Standard 304 contains up to 0.08% carbon, while 304L is a low-carbon grade capped at 0.03%. The lower carbon in 304L prevents carbide precipitation (sensitisation) during welding, giving welded assemblies better resistance to intergranular corrosion. For most bolted (non-welded) joints, standard 304 performs equally well.
In the fully annealed condition, grade 304 is essentially non-magnetic because of its austenitic structure. After cold working — such as thread rolling or heading — the fasteners can develop mild magnetic properties. This is normal and does not affect corrosion resistance or strength.
304 fasteners resist corrosion in fresh water and most atmospheric conditions. However, prolonged exposure to salt water or high-chloride environments can eventually cause pitting or crevice corrosion. For continuous marine or heavy-chloride service, grade 316 is usually recommended.
We supply metric sizes from M3 to M56 and imperial sizes from 3/16" to 4", in lengths from 3 mm to 200 mm as standard — with custom sizes, lengths and threads available on request.
Every order ships with an EN 10204 3.1 (or 3.2) Material Test Certificate, plus a Quality Assurance Plan, raw-material test reports, and full heat-number traceability so you can verify chemistry and mechanical properties.
Stainless Steel 304 fasteners are generally classified under HSN code 73181500.
Yes. Alongside our standard catalogue we produce made-to-drawing fasteners — special lengths, thread pitches, head styles and finishes — using CNC machining, cold/hot forging and thread rolling.
Get MTC-certified Stainless Steel 304 bolts, nuts, washers and studs — quoted fast and shipped worldwide.
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