Stainless steel 304 bolts are the most common stainless steel fasteners in the world, and for a reason. Also referred to as 18-8 stainless, grade 304 is a combination of approximately 18% chromium and 8% nickel that provides an excellent balance of corrosion resistance, ductility, and strength at an affordable price for budget-conscious projects. As manufacturers of precision bolts, we take S30400 raw materials and convert them into S30403 precision bolts that withstand humidity, freshwater, slight chemicals, and temperatures up to 870°C or more. Our SS 304 bolts are non-magnetic and austenitic, which means they are much more resistant to rust, oxidation, and intergranular attack than carbon or coated steel—hence their recommended use in construction, water treatment, food processing, railways, wind towers, and marine hardware. All of our fasteners are fully traceable, passivated, and third-party testable, whether you are about to use SS 304 hex bolts, stud bolts, anchor bolts, carriage bolts, or custom cold forging profiles. Here you can find the complete grade 304 bolt reference, including specifications, chemistry, mechanical data, size range, weight charts, and application guidance, so you can specify with complete confidence.
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What are Stainless Steel 304 Bolts?
An SS 304 bolt is an externally threaded fastener manufactured from AISI type 304 austenitic stainless steel, most commonly to the ASTM A193 / SA193 specification that governs high-quality bolting for pressure and general engineering service. The grade sits within the A193 family alongside classes B7, B8 and B8M, with the 304 variant chosen wherever moderate strength must be paired with dependable corrosion resistance.
Unifit Fastener produces the full 304 family — standard grade 304, low-carbon 304L for welded assemblies, and high-temperature 304H — across every common head and drive style. Our bolts are cold-forged for grain integrity, roll-threaded for fatigue strength, and finished by passivation as standard, with electroplating, hot-dip galvanizing, PTFE, black oxide and geometry coatings available on request.
Stainless Steel 304 Bolts Specifications
| Parameter | Specification |
|---|
| Specifications | ASTM A193 / ASME SA193 |
| Standards | DIN, ISO, JIS, GB, IS, BS, ASTM |
| Head Types | Hex, square, round, hex flange, flat, T-head, triangular |
| Neck Types | Hex, square, triangular, oval, knurled |
| Drive Types | Phillips, slotted, hex socket, Torx, square |
| Threads Available | UNC, UNF, BSW, BSF, Metric coarse & fine |
| Thread Configuration | ASME B1.1 2A/3A (inch) · B1.13M 6H-6G (metric) |
| Tolerance | ±0.01 mm to ±0.05 mm (OEM ±0.03 mm) |
| Surface Coatings | Passivation, zinc, HDG, PTFE, black oxide, geomet, Xylan |
| Production Capacity | 2,700,000 pieces / month |
Chemical Composition (%) — Stainless Steel 304 vs 304L vs 304H
| Grade | C | Mn | Si | P | S | Cr | Ni | N |
|---|
| 304 | 0.08 | 2.00 | 0.75 | 0.045 | 0.030 | 18.0–20.0 | 8.0–10.5 | 0.10 |
| 304L | 0.030 | 2.00 | 0.75 | 0.045 | 0.030 | 18.0–20.0 | 8.0–12.0 | 0.10 |
| 304H | 0.04–0.10 | 2.00 | 0.75 | 0.045 | 0.030 | 18.0–20.0 | 8.0–10.5 | – |
Values are maximum unless a range is shown. 304L limits carbon to reduce weld sensitisation; 304H holds carbon higher for elevated-temperature creep strength.
Stainless Steel 304 Bolts Mechanical Properties (Minimum Values)
| Property | A240 base (304/304L) | A193 B8 Cl.1 bolt | A193 B8 Cl.2 bolt (≤¾″) |
|---|
| Tensile min (MPa) | 515 / 485 | 515 | 860 |
| Yield 0.2% min (MPa) | 205 / 170 | 205 | 690 |
| Elongation min (%) | 40 | 30 | 12 |
| Hardness max | 92 HRB / 201 HB | 96 HRB / 223 HBW | 35 HRC / 321 HBW |
Physical Properties (Grade 304 / 304L / 304H)
| Property | Value |
|---|
| Density | 8,000 kg/m³ |
| Elastic Modulus | 193 GPa |
| Thermal Conductivity (0–100°C) | 16.2 W/m·K |
| Specific Heat (0–100°C) | 500 J/kg·K |
| Mean Thermal Expansion (0–100°C) | 17.2 µm/m·°C |
| Melting Point | approx. 1,400–45°C (2,550–°F range) |
| Magnetic Response | Non-magnetic (annealed) |
SS 304 Bolts Equivalent Grades & International Standards
Sourcing globally? Use this cross-reference to match Unifit’s SS 304 bolts to your local standard so specifications never get lost in translation.
| SS Grade | AISI | UNS | EN Numeric | EN Symbolic | JIS | BS | GOST / Werkstoff |
|---|
| 304 | 304 | S30400 | 1.4301 | X4CrNi18-10 | SUS 304 | 304S31 | X5CrNi18-10 |
| 304L | 304L | S30403 | 1.4306/1.4307 | X2CrNi18-9 | SUS 304L | 304S11 | 03X18H11 |
| 304H | 304H | S30409 | 1.4948 | X2CrNiN18-10 | SUS 304H | 304S51 | X5CrNi18-10 |
SS 304 Bolts Size & Dimensional Range
| Dimension | Range |
|---|
| Bolt Diameter (Metric) | M2 – M100 |
| Bolt Diameter (Inch) | 1/4″ – 4″ |
| Screw Size | M02 – M33 |
| Length | 3 mm – 500 mm |
| Dimensional Standard | ASME B18.2.1 (screws 6″ & shorter are fully threaded) |
| Thread Class | Class 2A (inspected with a No-Go gauge) |
SS 304 Bolt Types We Manufacture
A2-70 Stainless Steel Bolts
ASME SA 193 High Performance Anchor Bolts
ASTM A193 Grade 304 Threaded Expansion Anchor Bolt
ASTM A193 SS304 Hex Bolts
ASTM A193 UNS S30400 Eye Bolts
DIN 1.4301 Carriage Bolts
SS 304 Allen Bolts
SS 304 Countersunk Bolts
SS 304 Forged Hook Bolts
Stainless Steel 304 Stud Bolts
UNS S30400 12-Point Flange Bolts
UNS S30400 Lag Bolts
304 SS Hex Head Bolts
304 Stainless Steel Elevator Bolt
304 Stainless Steel J Bolts
304 Stainless Steel Torx Bolts
AISI 304 U Bolts
Alloy 304 Flange Head Bolts
SS 304 Bolts Applications & Industries
The 304 grade’s blend of strength, hygiene and corrosion resistance makes it the default fastener across dozens of sectors:
| Industry | Typical Use |
|---|
| Construction & Infrastructure | Structural steelwork, cladding, curtain walling, handrails |
| Marine & Coastal | Deck hardware, jetties, splash-zone fittings (freshwater/mild) |
| Water & Wastewater | Treatment plants, pumps, valves, tanks |
| Food & Beverage | Hygienic equipment, processing lines, conveyors |
| Renewable Energy | Wind tower assemblies, solar mounting structures |
| Railway & Automotive | Rolling stock, chassis brackets, trim fixings |
| Petrochemical & Power | Non-critical bolting, walkways, instrumentation supports |
| Electronics & Appliances | Enclosures, panels, non-magnetic assemblies |
Comparison: 304 vs 304L vs 316
Choosing the right stainless grade prevents both over-spending and premature failure. Here is how the popular options compare:
| Criteria | SS 304 | SS 304L | SS 316 |
|---|
| Key Alloying | 18Cr / 8Ni | 18Cr / 8Ni, low C | 16Cr / 10Ni + 2Mo |
| Carbon (max) | 0.08% | 0.030% | 0.08% |
| Tensile (min) | 515 MPa | 485 MPa | 515 MPa |
| Corrosion Resistance | Very good | Very good | Excellent (chlorides) |
| Weldability | Good | Excellent | Good |
| Chloride / Salt Water | Moderate | Moderate | Superior |
| Relative Cost | $ | $ | $$ |
| Best For | General & indoor use | Welded assemblies | Marine & chemical |
Rule of thumb: specify 304 for general and freshwater environments, 304L where welding is involved, and step up to 316 for saltwater, de-icing salts or aggressive chemicals.
Manufacturing & Quality Process
How We Make Every Bolt
- Wire drawing of certified UNS S30400 stainless coil to precise diameter.
- Cold heading to form the head profile with optimal grain flow.
- Thread rolling for work-hardened, fatigue-resistant threads.
- Heat treatment / solution annealing to restore ductility where required.
- Passivation and optional surface plating.
- Inspection, testing, marking and secure packing.
Quality Assurance & Testing
- PMI: Positive Material Identification confirms alloy chemistry on the shop floor.
- IGC: Intergranular corrosion testing per ASTM A262 on request.
- Mechanical: Tensile, proof-load, hardness and elongation checks against A193.
- Dimensional: No-Go gauge and CMM verification to Class 2A tolerances.
- Certification: EN 10204 3.1, PED 97/23/EC and Merkblatt AD 2000 W2 available.
Certifications & Standards
Unifit Fastener operates to internationally recognised quality systems, and each consignment ships with the documentation your inspectors expect:
- ASTM A193 / A194 and ASME SA193 bolting standards
- EN 10204 Type 3.1 manufacturer test certificates
- PED 97/23/EC and Merkblatt AD 2000-W2 compliance
- DIN, ISO, BS, JIS, GB and Werkstoff dimensional conformity
- Dual certification for grade 304 / 304L where specified
304 Hex Bolt Weight Reference
Approximate weight of DIN 933 / DIN 931 hex bolts in kilograms per 1,000 pieces. Use as an estimating guide; exact mass depends on length and finish.
| Length (mm) | M12 | M16 | M20 | M24 | M30 | M36 |
|---|
| 30 | 49.1 | – | – | – | – | – |
| 40 | 58.0 | 105 | – | – | – | – |
| 50 | 66.6 | 121 | 200 | 257 | – | – |
| 60 | 75.4 | 137 | 225 | 286 | – | – |
| 70 | 84.3 | 153 | 249 | 316 | 532 | – |
| 80 | 93.2 | 168 | 274 | 346 | 576 | – |
| 90 | 102 | 184 | 298 | 375 | 621 | 1224 |
| 100 | – | 199 | 322 | 405 | 665 | 1304 |
| 120 | – | 231 | 372 | 465 | 755 | 1455 |
| 150 | – | – | 446 | 554 | 890 | 1695 |
| 200 | – | – | – | – | 1114 | 2094 |
Stainless Steel 304/304H/304L Bolts Price List:
We offer wide range of industrial Stainless Steel 304, 304L, 304H Bolts that in compliance with IS, BS and DIN standards at best market prices in India. To know more about the latest price of Stainless Steel 304/304H/304L Bolts Please Call 91 22 66518521 or Send an Email to chirag@unifitmetalloys.com
Q. What is an SS 304 bolt made of?
A. An SS 304 bolt is made from austenitic stainless steel containing roughly 18% chromium and 8% nickel (the ‘18-8’ alloy), with the balance being iron. This chemistry, standardised as UNS S30400 / EN 1.4301, gives the bolt its corrosion resistance, strength and non-magnetic character.
Q. What is the difference between 304 and 304L bolts?
A. Grade 304L is a low-carbon version (0.030% max vs 0.08%). The reduced carbon prevents chromium-carbide formation during welding, so 304L is preferred for welded or heavily fabricated assemblies, while standard 304 suits general fastening at a marginally higher strength.
Q. Are 304 stainless steel bolts magnetic?
A. In the annealed condition, 304 bolts are essentially non-magnetic. Heavy cold working during forming can induce slight magnetism, but for practical purposes grade 304 fasteners are treated as non-magnetic.
Q. Can SS 304 bolts be used in seawater?
A. For continuous saltwater or chloride exposure we recommend grade 316 instead, because chlorides can cause pitting in 304. Grade 304 bolts perform well in freshwater, mild marine splash and general outdoor environments.
Q. What is the tensile strength of a grade 304 bolt?
A. Grade 304 bolts offer a minimum tensile strength of 515 MPa and a minimum 0.2% yield strength of 205 MPa, with around 40% elongation — ample for most structural and mechanical joints of moderate load.
Q. What sizes of SS 304 bolts does Unifit supply?
A. We supply SS 304 bolts from M2 to M100 (1/4″ to 4″) in lengths from 3 mm to 500 mm, in both coarse and fine threads, with custom sizes and profiles made to order.
Q. Do your 304 bolts come with test certificates?
A. Yes. Every batch ships with EN 10204 3.1 manufacturer test certificates and full mill traceability, with PED and third-party inspection available on request.
Q. What is the maximum service temperature for 304 bolts?
A. Grade 304 bolts retain useful strength and oxidation resistance up to approximately 870°C in intermittent service, making them suitable for many elevated-temperature applications.