GRADE FAMILY
Ferritic and martensitic stainless steels
Ferritic grades (409, 430, 444) are chromium stainless steels without nickel, magnetic, economical but less ductile than austenitics. Martensitic grades (410, 420) share a similar chromium base but can be heat-treated for hardness. Two families often mentioned together, with genuinely different uses.
What is a ferritic or martensitic stainless steel?
Ferritic grades are chromium stainless steels with no added nickel, with a body-centred cubic structure and therefore magnetic. Martensitic grades share a similar chromium base but contain enough carbon to be hardened and tempered, making them hard but more brittle and less corrosion-resistant than austenitics.
When to choose this family — and when not to?
Ferritic grades suit general mechanical parts, exhaust systems and components where cost outweighs chemical resistance. Martensitic grades are chosen for hardness and wear resistance, not process piping. Avoid both in chlorinated environments or demanding sanitary use — choose an austenitic grade instead.
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.
| Grade (example) | EN | Indicative PREN |
|---|---|---|
| 409 | — | — |
| 430 | 1.4016 | 16–18 |
| 444 | 1.4521 | 23–28 |
| 410 | — | — |
| 420 | — | — |
PREN notes
- 430
- Lower than 304L. 430 is not a corrosion-resistant grade for aggressive environments.
- 444
- Comparable to 316L, without a single gram of nickel. That's the whole logic of this grade.
Typical applications for this family: Mechanical engineering · Exhaust systems · Wear resistance.
See also: Grade equivalents → · PREN calculator →
Available forms and dimensions
Tubes, fittings, flanges and bars available depending on grade and supplier. Grade 444 is found as heat-exchanger tube at some specialised suppliers. Precise dimensions are not yet documented in our structured reference data for this family: send us your requirement (diameter, wall thickness, length) via a quote request — we check with our partner mills and confirm within 2 to 3 business days.
Applicable standards
- ASTM A268/A268M
- ASME SA268
- EN 10088-2
Frequently asked questions
- Why are ferritic grades cheaper than austenitics?
- Because they contain no nickel, the most expensive alloying element in stainless steel. Grade 430, for instance, has chromium as its only main alloying element — hence a noticeably lower cost index than 304L at equal volume.
- Can a martensitic grade be welded like an austenitic one?
- No: martensitic grades harden as they cool after welding, which can crack the weld without proper preheat and post-weld heat treatment. A fabrication constraint to check with the supplier before specifying these grades in welded piping.
- Is 444 really ferritic despite its use in heat exchangers?
- Yes: 444 is a stabilised ferritic grade, chosen in heat exchangers for its resistance to stress corrosion — which austenitics can suffer in hot chlorinated environments — not for its cold mechanical properties.
- My grade isn't on the list — what should I do?
- These examples are not a closed catalogue. Send us your exact designation (409, 439, 420J2...) via a quote request — we check availability with our partner mills.