ASTM F593
Group 1
AISI 304 / 304L Bolts
304 vs 304L — What “L” Actually Changes
AISI 304 and 304L share the same fundamental 18% chromium, 8% nickel austenitic composition that gives this alloy family its broad, well-established corrosion resistance across general atmospheric, food-contact, mild chemical, and architectural environments — chromium forms a self-healing passive oxide layer, and nickel stabilizes the austenitic microstructure that gives stainless steel its combination of strength, ductility, and weldability.
The “L” designation means low carbon — 304L caps carbon content meaningfully lower than standard 304, a deliberate change made specifically to address a real corrosion mechanism called sensitization, where welding heat can cause chromium to migrate and combine with carbon at grain boundaries near the weld, locally depleting the chromium available for passive film formation and creating a corrosion-prone zone. 304L’s lower carbon content genuinely reduces this risk, making it the correct choice specifically where the fastener assembly involves welding nearby, or where post-weld heat-affected zones are a real service concern.
For fasteners not directly involved in welded assemblies, standard 304 remains entirely appropriate and slightly more economical — the distinction genuinely matters most where weld-adjacent corrosion resistance is a specific design concern, not as a universal upgrade.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our ASTM F593 Group 1 fastener range is manufactured and verified by chemical composition and mechanical testing under our ISO 9001:2015 quality system.
A Note on Standard Scope
ASTM F593 covers externally threaded stainless fasteners including bolts, hex cap screws, and studs. If your requirement is for matching nuts, ASTM F594 is the companion nut specification typically paired with F593 — please let us know if you’d like both quoted together for a matched Group 1 assembly.
Where This Material Genuinely Applies
Genuine, Broad Corrosion Resistance
Well-balanced chromium and nickel content for general atmospheric and mild chemical exposure.
The Industry-Standard Default
The most widely stocked, specified, and commercially available stainless fastener grade.
304L Weld-Decay Protection
Low carbon content genuinely reduces sensitization risk near welded assemblies.
Verified Mechanical Properties
Batch testing confirms genuine alloy content and mechanical properties for every lot.
Group 1 (304) vs Group 2 (316) — Quick Reference
Confirming whether chloride exposure genuinely requires 316’s added molybdenum before paying for the higher grade. This table is the quick reference we use with buyers before quoting.
| Aspect | Group 1 (304/304L) | Group 2 (316/316L) |
|---|---|---|
| Base Composition | 18% Cr, 8% Ni | 16-18% Cr, 10-14% Ni, +Mo |
| Chloride/Pitting Resistance | Good, general exposure | Genuinely superior, molybdenum-enhanced |
| Cost | More economical | Higher, for the added resistance |
| Best Suited For | General atmospheric, food, mild chemical | Marine, coastal, or chloride-heavy service |
Group 1 (304/304L) Specification Details
Nominal Composition
- Chromium 18.0 – 20.0%
- Nickel 8.0 – 10.5%
- Carbon (304) ≤0.08%
- Carbon (304L) ≤0.03%
Typical Mechanical Range
- Condition Cold Worked / Annealed
- Corrosion Resistance General Atmospheric & Mild Chemical
- Weld-Decay Resistance 304L Enhanced
- Fastener Standard ASTM F593 Group 1
Fastener Types We Manufacture
- Hex Bolts & Cap Screws Standard & Custom Sizes
- Studs Standard & Custom Sizes
- Matching Nuts ASTM F594, On Request
- Washers Matching Material
Application Areas
Wherever general corrosion resistance is needed without the specific chloride/marine exposure that would call for 316 instead.
Food Processing & Kitchen Equipment
hygienic equipment
Architectural & Structural Fastening
exterior and interior fastening
Chemical & Pharmaceutical Equipment
equipment fastening
General Industrial & Piping Applications
resistant fastening needs
Standard Export Documentation
Prepared as standard practice for every ASTM F593 Group 1 fastener shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Chemical Composition Report
Confirms actual chromium, nickel, and carbon content fall within the specified 304/304L range.
Certificate of Conformance
Confirms the shipment matches the purchase order grade/size specification in full.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
NABL Accredited Test Reports
Independent mechanical and dimensional testing available on request.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
Internationally Recognised Standards Coverage
Related Fastener Grades & Materials
ASTM A194 Grade 8 Nuts
Our standard 304-equivalent stainless nut grade, the common counterpart to Group 1 bolting.
View Grade 8 Nuts →ASTM A194 Grade 8M Nuts
Our 316-equivalent stainless nut grade, for marine or coastal chloride exposure beyond Group 1.
View Grade 8M Nuts →ASTM F593 Alloy 20 (UNS N08020)
Our sulfuric-acid-resistant nickel alloy, for chemical service beyond standard stainless capability.
View Alloy 20 →Stainless Steel Fasteners Manufacturer India
Our broader fastener manufacturing capability across all major carbon, alloy, stainless, and non-ferrous grades.
View SS Manufacturer Guide →General Corrosion
Resistant Fastening?
Tell us your application and whether welding is involved nearby — we’ll confirm whether 304 or 304L fits, and quote with full documentation, matched nuts included on request. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in