304L Stainless Steel Coil (UNS S30403 / 1.4307)

Key takeaways: 304L coil at a glance

• Grade identity: 304L (UNS S30403, Werkstoff 1.4307, JIS SUS304L) is the low-carbon sibling of 304 in the austenitic stainless steel family, roughly 18% chromium and 8-12% nickel with no molybdenum.
• Why the "L": carbon held to ≤0.03% suppresses chromium-carbide precipitation, so the weld HAZ resists intergranular corrosion. That is the whole reason to pay for 304L over 304.
• Coil form: this is the master mill coil / strip, the flat input that is slit to width, re-coiled or cut-to-length into 304L sheet. Available in 2B, BA and No.4 finishes.
• Corrosion ceiling: PREN is only ~18, the bottom of the pitting ladder. Fine for mild, atmospheric and freshwater service; the moment chlorides appear, step up to 316L.
• Traceable supply: genuine mill coil with an EN 10204 3.1/3.2 mill test certificate provided with every order, ex-stock for immediate dispatch.

What is 304L stainless steel coil?

304L is a controlled-carbon version of 304, not a different alloy. The chromium (18-20%) and nickel (8-12%) ranges overlap with 304; the one change that matters is carbon, capped at ≤0.03% instead of ≤0.08%. That keeps it fully austenitic, non-magnetic in the annealed condition, ductile and easy to deep-draw, press and roll-form.

Coil is the master form. Flat stainless is produced as continuous band, cold-reduced, annealed and finished on a line, then shipped as coil. That coil is the input to everything downstream: it is slit into narrower strip, re-coiled, or cut-to-length into sheet. You specify 304L in coil form rather than pre-cut sheet when you are feeding a slitting line, a press shop, a roll-former or a tube mill and want the material in its continuous, as-rolled state. For the grade across every form, see the 304L grade hub; for how coil relates to flat-cut product, see sheet vs plate vs coil.

Chemical composition

304L coil is supplied to the UNS S30403 chemistry of ASTM A240 (weight %, balance iron). The 304 column is shown alongside; the carbon ceiling is the only difference that changes how the steel behaves.

Why the ≤0.03% carbon matters (sensitization)

Hold standard 304 in the 425-815 °C range, exactly what happens in the heat-affected zone of a weld, and carbon combines with chromium to precipitate chromium carbides at the grain boundaries. The depleted zone loses its passive film and corrodes intergranularly. Cap carbon at ≤0.03% and 304L starves that reaction before it starts, so welded fabrications stay corrosion-resistant with no post-weld solution anneal. The alternatives are a stabilized grade such as 321/347 or a full solution anneal after welding. For the mechanism and how to avoid it, see how to prevent sensitization and intergranular corrosion (sensitization).

Mechanical properties

Minimum room-temperature properties for annealed 304L strip/coil per ASTM A240. The low-carbon chemistry costs a little strength against plain 304, the trade-off you accept for as-welded corrosion resistance.

Cold-work tempers (¼-, ½- and full-hard strip)

Like all 18-8 grades, 304L work-hardens rapidly. Cold-rolled strip can be supplied in tempers, quarter-hard through full-hard, that raise tensile and yield strength well above the annealed minimums at the cost of elongation. Specify the temper when a part relies on spring-back or surface hardness; specify annealed when it must be deep-drawn or roll-formed. The same cold work makes the surface slightly magnetic even though annealed 304L is non-magnetic.

Physical properties

The density figure is not academic for coil buyers; it is the number that drives the coil-weight calculation further down this page.

Corrosion behavior & PREN: what 304L coil resists and what it doesn't

304L resists general atmospheric corrosion, potable water, many organic acids, foodstuffs and most dry indoor environments. It shares the exact corrosion ceiling of 304, because the low carbon changes weldability, not pitting resistance. Three mechanisms every specifier should recognize before choosing it:

Pitting & PREN ~18

With no molybdenum, 304L carries a PREN of only ~18 (PREN = Cr + 3.3·Mo + 16·N) and sits at the bottom of the pitting ladder: 304L (~18) < 316L (~24) < 904L (~34). In chloride-bearing water, seawater, de-icing salts, coastal air or chlorinated process streams, it is prone to pitting corrosion. The practical rule: if free chlorides are present, 304L is the wrong grade.

Chloride stress-corrosion cracking

Like all austenitic grades, 304L is susceptible to chloride stress-corrosion cracking, sudden branching cracks under the combination of tensile stress, chlorides and warm temperatures (typically above ~50-60 °C). The low carbon does not cure this; it is a family trait of the austenitics.

Intergranular corrosion: the one 304L is built to beat

This is where 304L earns its place. Standard 304 (C ≤ 0.08%) can sensitize in the weld HAZ; 304L (C ≤ 0.03%) does not, so it welds into tanks and ducting without a post-weld anneal. For the full decision between the two, see 304 vs 304L.

Equivalent grades & designations

For a full cross-walk between systems, see the UNS / Werkstoff / JIS cross-reference.

304L coil vs the alternatives: when to choose it

vs 304: the sensitization decision

304L and 304 share the same corrosion ceiling; the difference is carbon. 304L caps carbon at ≤0.03% so the weld HAZ does not sensitize, at a small cost in yield strength. Choose 304L for welded fabrications that cannot be post-weld annealed, and plain 304 where the part is not welded or will be fully re-annealed. See 304 vs 304L.

vs 316L: the chloride decision

316L adds 2-3% molybdenum, lifting its PREN to ~24 and giving it the chloride-pitting resistance 304L lacks, while keeping the same low-carbon weldability. Choose 304L for dry, indoor, food and architectural duty where it is the economical choice; choose 316L the moment chlorides, seawater or marine air enter the service. This is the single most common 304L specification error, see 304L vs 316L.

Coil finishes

Finish is the primary coil decision; it sets both appearance and the base condition for any downstream polishing. Nandini Steel supplies 304L coil in the workhorse finishes below.

Common finish-selection mistake

A recurring error from the stockyard: ordering 2B and then discovering the part needs a mirror polish. If the end result must be bright or polished, start from BA; polishing up from a 2B surface adds cost and time. Confirm the final surface requirement before the coil finish is locked. For the full breakdown, see stainless steel finishes: 2B, BA, No.4.

Forms, dimensions & slitting

304L coil is held as both cold-rolled (CR) and hot-rolled (HR) master coil and slit to the width a job needs. Cold-rolled coil covers the thinner gauges and the 2B/BA/No.4 finishes; hot-rolled annealed-pickled (No.1) coil covers the heavier gauges. Coil is supplied on standard inner diameters for mill handling, master-coil or slit, and can be cut down to strip or sheet.

Because dimensional availability moves with stock, the exact thickness, width and slit-width ranges held at any time are confirmed on inquiry; request current stock and tolerances with your RFQ.

Other 304L forms

Need flat-cut product rather than coil? See 304L sheet and 304L plate, or the full 304L grade hub.

Coil weight & how to calculate

Coil weight follows directly from the dimensions and the density of 304L (7.93 g/cm³). For a flat strip, weight per running meter is:

kg per meter = thickness (mm) × width (mm) × 7.93 ÷ 1000

Worked example, a 1.2 mm × 1250 mm coil:

1. Multiply thickness by width: 1.2 × 1250 = 1500 mm².
2. Multiply by density and divide by 1000: 1500 × 7.93 ÷ 1000 = 11.9 kg per meter.
3. Multiply by coil length to get the full coil mass, e.g. a 500 m coil ≈ 5,950 kg.

To run your own dimensions, use the weight calculator.

Standards & specifications complied

304L coil is supplied to the recognized flat-product standards:

• ASTM A240, chromium and chromium-nickel stainless steel plate, sheet and strip for pressure vessels and general application (the primary specification for 304L flat product).
• ASME SA-240, the ASME Boiler & Pressure Vessel Code adoption of A240.
• ASTM A480, general requirements, chemistry limits and dimensional tolerances for flat-rolled stainless.
• ASTM A262, practices for detecting susceptibility to intergranular attack, the acceptance test that confirms 304L is not sensitized.

Testing, inspection & certification

Every 304L coil ships with an EN 10204 3.1/3.2 mill test certificate provided with every order, giving the heat/cast chemistry and mechanical results traceable to the melt. For welded and corrosion-critical work, intergranular-corrosion testing per ASTM A262 confirms the material is not sensitized, and PMI (positive material identification) verifies grade at receiving. Learn more about the EN 10204 3.1 mill test certificate levels and how we handle testing, MTC, NDT and PMI.

Applications of 304L coil by industry

304L coil is the default welded-fabrication flat product across general industry and hygienic processing:

• Food & dairy processing, welded tanks, hoppers, conveyors and panels in clean, non-chloride environments.
• Architectural & cladding, facades, trims and interior panels, usually in BA or No.4 finish.
• General fabrication, welded enclosures, ducting, vessels and roll-formed components where the HAZ must stay corrosion-resistant.

The boundary is chlorides: for marine, coastal or salt-water exposure, 304L pits, so specify 316L instead.

Welding & fabrication of 304L coil

304L is readily welded by TIG, MIG and resistance methods. The matching filler is ER308L, a low-carbon austenitic consumable whose weld metal resists HAZ sensitization. Because the base metal is already low-carbon, 304L fabrications can go into service as-welded without a post-weld solution anneal in most sections. 304L forms and deep-draws well but work-hardens quickly, so it is "gummy" to machine and benefits from sharp tooling, positive feeds and interstage annealing on severe draws. See how to weld 304L, how to weld 304, weld decay and filler selection and heat treatment / solution annealing (solution anneal ~1010-1120 °C followed by rapid quench).

Pricing & how we quote

304L coil is a commodity flat product whose price tracks the nickel surcharge and the LME daily, so we do not publish fixed price tables. We quote live against your exact finish, gauge, slit width and quantity. All stock is ex-stock and available for immediate dispatch; send your specification for a current quotation by RFQ or WhatsApp +91 99202 09184.

FAQ

Request a quote for 304L stainless steel coil

Nandini Steel is an ISO 9001:2015-certified stockist and supplier, established in 2003, with 307+ projects delivered for 260+ clients across 36+ export countries over 20+ years. We hold genuine mill 304L coil ex-stock for immediate dispatch, slit to width, in 2B, BA and No.4 finishes, every order shipped with an EN 10204 3.1/3.2 mill test certificate.

• Phone: +91 22 43404600 · +91 9920209184
• WhatsApp: +91 99202 09184
• Email: reachus@nandinisteel.com
• Address: 25, Dreamland Building, 601, 6th Floor, Mama Parmanand Marg, Charni Road, Opera House, Girgaon, Mumbai, Maharashtra 400004, India
• GSTIN: 27ADJPA7240C1Z0

Send your finish, gauge, slit width and quantity for live pricing, request an RFQ.

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