Are 304L and 316L interchangeable?

No: 316L contains 2 to 2.5% molybdenum that 304L doesn't, which improves its chloride resistance. For a non-chlorinated environment, the price difference isn't justified; with moderate chlorides present, 316L is the default choice.

Why choose a stabilised grade (316Ti, 321H, 347H) over a standard 316L or 304L?

To hold up under continuous high-temperature service or to avoid intergranular corrosion after heavy welding, where carbon can precipitate at grain boundaries. Titanium (316Ti, 321H) or niobium (347H) pin down that carbon. Without that specific need, a standard 316L or 304L is sufficient and costs less.

Does an austenitic grade hold up in seawater?

Not reliably in continuous service: even 316L remains exposed to crevice corrosion and pitting in warm seawater. For that environment, a duplex or super austenitic grade is the usual choice — see their dedicated pages.

My austenitic grade isn't in the table above — what should I do?

This table is an extract, not a closed catalogue — the austenitic family includes many more variants (317L, low-sulphur grades...). Send us your exact designation via a quote request and we will confirm availability.

GRADE FAMILY

Austenitic stainless steels

Austenitic grades are the most common family in industrial stainless: a non-magnetic Cr-Ni structure, good weldability, a wide service temperature range. 304L and 316L cover most requirements; the stabilised grades 316Ti, 321H and 347H hold up at high temperature and resist intergranular corrosion after welding.

What is an austenitic stainless steel?

An austenitic stainless steel is an iron-chromium-nickel alloy with a face-centred cubic crystal structure, stable at room temperature thanks to the nickel content. This structure makes it non-magnetic, highly weldable and ductile across a wide temperature range, from cryogenic service to several hundred degrees depending on grade and carbon content.

When to choose this family — and when not to?

Choose it for general process piping, food processing, pharmaceuticals and fresh-to-moderately-chlorinated water networks: a strong cost-performance balance with wide availability in both welded and seamless tube. Avoid it for seawater or hot concentrated chloride environments, where a duplex or super austenitic grade resists crevice corrosion and pitting better.

Grades in this family

The grades listed are examples, never a closed catalogue — every grade belongs to one of the nine families, which is what makes this claim reliable.

Examples in the austenitic stainless steels family (familles-nuances.json), EN and PREN filled in from nuances-inox.json when the entry exists — not a closed catalogue
Grade (example)	EN	Indicative PREN
304/L	1.4307	18–20 ¹
316/L	1.4404	24–26 ¹
316Ti	1.4571	24–26 ¹
321/H	1.4541	18–20 ¹
347H	no exact equivalent	17–19 †
317L	1.4438	28–33

† PREN is calculable but not the deciding factor for this grade, see the note below · ¹ inherited value, not yet cross-checked against a product standard.

PREN caveats (†)

347H: ⚠️ PREN is not the deciding factor for this grade. 347H is chosen for creep resistance and stabilisation, not aqueous corrosion — its pitting resistance is at the level of a 304.

PREN notes

317L: Notably higher than 316L (24–26) thanks to molybdenum raised to 3–4%. That's the reason this grade exists.

Typical applications for this family: Chemical processing · Food processing · Pharmaceuticals · Heat exchangers and piping outside RCC-M scope.

My grade isn't listed →

Available forms and dimensions

Available as welded and seamless tube, heat-exchanger tube, weld fittings, flanges and bars — the most complete family in terms of forms among our partner mills. U-tubes, non-standard lengths and polished sanitary finishes are available on request. Outer diameter from 6 to 610 mm — structured data available for 304/L, 316/L, 316Ti, and 321/H only. The other grades in this family don't yet have this in our structured reference data: send us your requirement via a quote request.

Applicable standards

EN 10216-5
EN 10217-7
ASTM A312
ASTM A213
ASTM A249
ASTM A269
ASTM A270
EN 10088-1

Frequently asked questions

Are 304L and 316L interchangeable?: No: 316L contains 2 to 2.5% molybdenum that 304L doesn't, which improves its chloride resistance. For a non-chlorinated environment, the price difference isn't justified; with moderate chlorides present, 316L is the default choice.
Why choose a stabilised grade (316Ti, 321H, 347H) over a standard 316L or 304L?: To hold up under continuous high-temperature service or to avoid intergranular corrosion after heavy welding, where carbon can precipitate at grain boundaries. Titanium (316Ti, 321H) or niobium (347H) pin down that carbon. Without that specific need, a standard 316L or 304L is sufficient and costs less.
Does an austenitic grade hold up in seawater?: Not reliably in continuous service: even 316L remains exposed to crevice corrosion and pitting in warm seawater. For that environment, a duplex or super austenitic grade is the usual choice — see their dedicated pages.
My austenitic grade isn't in the table above — what should I do?: This table is an extract, not a closed catalogue — the austenitic family includes many more variants (317L, low-sulphur grades...). Send us your exact designation via a quote request and we will confirm availability.