304 and 316 stainless steel: grades, properties and how to choose
304 and 316 are the two most specified stainless steel grades, and the choice between them comes down to corrosion environment. 304 (1.4301) is the general-purpose grade; 316 (1.4404) adds molybdenum for chlorides, marine and chemical exposure. ULAMEX stocks both, plus 304L, 316Ti, ferritic 430 and duplex 2205, as profiles, sheet, rods and pipes, to EN 10088, with a 3.1 certificate on request. This guide explains the grades, their composition and properties, the finishes, and how to choose.
What makes steel stainless
Stainless steel owes its corrosion resistance to a minimum chromium content of 10.5 percent, which forms a thin, self-healing passive oxide layer on the surface. That passive layer is what lets stainless steel survive where carbon steel or galvanised steel would rust, from food and pharmaceutical plants to marine and chemical installations. Adding nickel makes the steel austenitic (the 300 series), which is tough, formable and weldable; adding molybdenum sharpens resistance to chlorides.
Stainless steel grade families ULAMEX stocks
Stainless steels split into families by microstructure, and ULAMEX holds the common grades across the families that matter for fabrication and construction. All are supplied to EN 10088-1, EN 10088-2 and EN 10088-3 with inspection documents per EN 10204.
| Family | Grades stocked | Character |
|---|---|---|
| Austenitic | 1.4301 (304), 1.4307 (304L), 1.4404 (316L), 1.4571 (316Ti) | Tough, formable, weldable, non-magnetic when annealed |
| Ferritic | 1.4016 (430) | Cost-effective, magnetic, decorative and light structural |
| Duplex | 1.4462 (2205) | High strength and chloride resistance, weakly magnetic |
304 stainless steel (1.4301, V2A)
Grade 304 (1.4301), known as V2A in Germany, is the most widely used stainless steel and the default for general-purpose work. It combines good corrosion resistance, formability and weldability at a sensible cost, which makes it the standard for kitchen and food equipment, balustrades, cladding, tanks and general fabrication in non-aggressive environments. The low-carbon variant 304L (1.4307) is preferred where heavier sections are welded, as the lower carbon avoids carbide precipitation at the weld.
For outdoor use with minimal salt exposure, 304 is suitable. Where chlorides are present, from coastal air to de-icing salt or swimming pools, step up to 316L.
316 and 316L stainless steel (1.4401, 1.4404, V4A)
Grade 316 adds 2 to 2.5 percent molybdenum to the 304 base, which significantly improves resistance to chlorides and aggressive chemicals. Known as V4A, it is the grade for marine environments, chemical processing, pharmaceutical equipment and anywhere exposed to salt or acidic media. The low-carbon version 316L (1.4404) is the standard stocked grade, as its low carbon makes it the safe choice for welded fabrication. The stabilised grade 316Ti (1.4571) suits elevated-temperature service.
If a job sees salt, chlorinated water or acidic foods and cleaning agents, 316L is the right call. For the most severe marine and chemical duty, duplex 2205 goes further again.
304L, 316Ti and 430 in detail
304L (1.4307) is the low-carbon version of 304, with carbon capped at 0.030 percent to avoid carbide precipitation when heavier sections are welded, so it is the safe choice for welded 304 fabrication. 316Ti (1.4571) is titanium-stabilised 316, which resists sensitisation at elevated temperature and suits hot service where a standard 316 would be at risk. 430 (1.4016) is a ferritic, magnetic grade with lower alloy content and cost; it has moderate corrosion resistance and is used for decorative and light interior work, appliance panels and trim where chlorides are not a concern.
Duplex 2205 and the other stocked grades
Beyond the mainstream 304 and 316, ULAMEX stocks several grades for specific duties. Duplex 2205 (1.4462) has a mixed ferritic-austenitic microstructure that gives roughly double the proof strength of 304 together with excellent chloride and stress-corrosion resistance, the grade for critical marine and high-load structures. 316Ti (1.4571) is titanium-stabilised for elevated-temperature service. 304L (1.4307) is the low-carbon 304 for heavy welded sections. Ferritic 430 (1.4016) is a cost-effective, magnetic grade for decorative and light structural work where chloride resistance is not critical.
304 versus 316: how to choose
The decision is almost always about the environment, not strength. The table maps the common cases.
| Environment | Recommended grade |
|---|---|
| Indoor, general fabrication, dry | 304 (1.4301) |
| Outdoor, low salt exposure | 304 (1.4301) |
| Coastal, pool, de-icing salt | 316L (1.4404) |
| Marine, chemical, pharmaceutical | 316L (1.4404) |
| Severe marine, high chloride, high load | Duplex 2205 (1.4462) |
| Cost-driven decorative or light structural | 430 (1.4016) |
Corrosion resistance and pitting (PREN)
The passive chromium oxide layer protects stainless steel, but in the presence of chlorides it can break down locally and cause pitting. Resistance to pitting is summarised by the Pitting Resistance Equivalent Number (PREN), calculated as PREN = Cr + 3.3 x Mo + 16 x N. The higher the PREN, the better the grade resists chloride pitting.
This is why 316L, with its 2 to 2.5 percent molybdenum, outperforms 304 in coastal and chemical service, and why duplex 2205, with higher chromium, molybdenum and nitrogen, outperforms both. For a borderline environment, comparing PREN values is a quick way to rank candidate grades; for the exact duty, send the chloride level and temperature with your enquiry.
Types of corrosion to design against
Stainless steel resists general corrosion well, but four localised forms guide grade selection. Pitting is localised attack in chlorides, ranked by PREN, and is why 316L and duplex outperform 304 at the coast. Crevice corrosion occurs in tight gaps and under deposits where oxygen is depleted, so joints and fasteners are detailed to avoid crevices. Stress-corrosion cracking can crack austenitic 304 and 316 under the combination of tensile stress, chlorides and warmth, which is where duplex 2205 is specified. Galvanic corrosion occurs when stainless is coupled to a less noble metal in a wet circuit, so dissimilar metals are isolated. Matching the grade and the detail to these mechanisms is what makes a stainless installation last.
Mechanical properties
The austenitic grades are specified to EN 10088-2 for flat products. The values below are typical minimums for cold-rolled annealed sheet and vary with product form and thickness; the exact figures for a delivered batch appear on the EN 10204 3.1 certificate.
| Property (annealed sheet) | 304 (1.4301) | 316L (1.4404) |
|---|---|---|
| Proof strength Rp0.2 (min.) | 230 MPa | 200 MPa |
| Tensile strength Rm | 540 to 750 MPa | 500 to 700 MPa |
| Elongation A (min.) | 45 percent | 40 percent |
| Corrosion resistance | Good (general) | Very good (chlorides, marine) |
| Weldability | Good (304L for heavy welds) | Very good |
Chemical composition
Composition limits follow EN 10088-1. The defining elements are chromium, nickel and, for the 316 family, molybdenum; the low-carbon (L) grades cap carbon at 0.030 percent for welding.
| Grade | C (max) | Cr | Ni | Mo |
|---|---|---|---|---|
| 304 (1.4301) | 0.07 | 17.5 to 19.5 | 8.0 to 10.5 | – |
| 304L (1.4307) | 0.03 | 17.5 to 19.5 | 8.0 to 10.5 | – |
| 316L (1.4404) | 0.03 | 16.5 to 18.5 | 10.0 to 13.0 | 2.0 to 2.5 |
| 316Ti (1.4571) | 0.08 | 16.5 to 18.5 | 10.5 to 13.5 | 2.0 to 2.5 |
| 2205 (1.4462) | 0.03 | 21.0 to 23.0 | 4.5 to 6.5 | 2.5 to 3.5 |
| 430 (1.4016) | 0.08 | 16.0 to 18.0 | – | – |
Welding and fabricating stainless steel
Austenitic stainless steels weld readily by TIG and MIG. The usual filler matches the base grade: 308L for 304 and 316L for 316. Two points protect corrosion resistance at the weld.
First, sensitisation: holding the steel in the 450 to 850 degrees C range during welding can precipitate chromium carbides at the grain boundaries and lower local corrosion resistance. The low-carbon L grades (304L, 316L) avoid this, which is why they are preferred for welded fabrication. Second, contamination: stainless must be kept away from carbon steel tools, brushes and grinding media, because embedded iron particles rust and stain the surface. Dedicated stainless tooling and back-purging of welds keep the finished part clean and corrosion resistant.
Surface finishes
Stainless steel sheet is supplied in several mill and polished finishes, and the right one depends on whether the surface is industrial, hygienic or visible.
| Finish | Description | Typical use |
|---|---|---|
| 2B | Standard cold-rolled, smooth and slightly reflective | Industrial and general fabrication |
| BA (bright annealed) | Reflective, smoother, produced in a controlled atmosphere | Hygienic food and pharmaceutical surfaces |
| No.4 (brushed) | Directional satin texture from mechanical polishing | Visible architectural surfaces |
| No.8 (mirror) | Highly polished, reflective | Decorative and feature surfaces |
When ordering stainless steel sheet, state the finish on the order line, as it is set at the mill and confirmed on the dispatch note.
Designations and equivalents
The same grade carries several names across standards, and a buyer often has to cross-reference them on a drawing or an order. The European EN material number is the reference that travels across borders; the AISI type name is common in trade, and the UNS number is used in North American specifications. Sheet and plate are supplied to EN 10088-2, bar and section to EN 10088-3.
| EN number | AISI type | UNS | Common name |
|---|---|---|---|
| 1.4301 | 304 | S30400 | V2A, 18/8 |
| 1.4307 | 304L | S30403 | 304L |
| 1.4401 | 316 | S31600 | V4A |
| 1.4404 | 316L | S31603 | 316L |
| 1.4571 | 316Ti | S31635 | 316Ti |
| 1.4462 | 2205 | S32205 | Duplex 2205 |
| 1.4016 | 430 | S43000 | Ferritic 430 |
Forms, sizes and standards available from ULAMEX
ULAMEX supplies stainless steel as four product groups. Stainless steel profiles cover angle, channel, flat bar and sections; sheet covers smooth, perforated and tear plate; rods cover round, square and hexagonal bar; and stainless steel tube and pipe covers round and rectangular sections. All grades are available across the forms.
| Standard | Scope |
|---|---|
| EN 10088-1 | List of grades and chemical composition |
| EN 10088-2 | Sheet, plate and strip for general use |
| EN 10088-3 | Bar, rod, wire, sections and profiles |
| EN 10204 | Inspection document types (3.1 on request) |
Stainless steel tube and pipe
Stainless steel tube and pipe is supplied in round and rectangular sections, in 304 and 316L as standard. Welded tube covers most architectural and general work, while seamless is specified where pressure or the most demanding service requires it. Common uses are handrails and balustrades (often in a No.4 brushed finish), food and process pipework, and light structural frames.
Specify the grade, the outside dimension and wall thickness, the finish and whether welded or seamless, and ULAMEX will confirm availability and quote. Stainless tube sits alongside profiles, sheet and rod, so a mixed fabrication order travels together.
Food contact and hygiene
Grades 304 (1.4301) and 316L (1.4404) are approved for direct food contact under EU Regulation 1935/2004, which is why they dominate processing tanks, conveyor systems, work surfaces and brewery equipment. For surfaces that have to be cleaned to a hygiene standard, a 2B or BA finish gives the smooth, non-porous surface required. Where salt, acidic foods or chloride-based cleaning agents are involved, 316L is the preferred grade. This pairing of grade and finish is the everyday specification for fabrication shops serving food and pharmaceutical plants.
Is stainless steel magnetic?
It depends on the family. The austenitic grades (304, 316, 316Ti) are generally non-magnetic in the annealed condition, although cold working can induce slight magnetism. Ferritic grade 430 is magnetic, and duplex 2205 is weakly magnetic because of its mixed microstructure. A magnet is therefore a rough sorting aid, not a reliable grade test; the 3.1 certificate confirms the grade.
Why stainless steel can still rust
Stainless steel is corrosion-resistant, not corrosion-proof, and it can stain or pit in the wrong conditions. The usual causes are surface contamination with free iron, from carbon steel tools, grinding dust or storage, which rusts and stains the surface; and chlorides, which break down the passive layer and cause pitting, especially on 304 in coastal or pool environments. Tea-staining, a light brown surface discolouration, is the mild form seen on 304 near the coast. The fixes are choosing the right grade (316L or duplex for chlorides), keeping stainless away from carbon steel, and passivating the finished part.
Passivation is a controlled acid treatment that removes free iron and restores the passive chromium oxide layer, and pickling removes weld heat tint; together they return the full corrosion resistance of the grade. In service, stainless needs only periodic cleaning with water or a mild detergent, avoiding abrasive pads and chloride-based cleaners.
Stainless steel by sector
The grade and finish change with the sector, but the same stocked grades cover the field.
Food and pharmaceutical. 304 and 316L in 2B or BA finish for tanks, conveyors, work surfaces and process equipment, approved for food contact. Marine and chemical. 316L and duplex 2205 for saltwater, chlorides and aggressive media. Architecture. 304 and 316 in No.4 brushed or No.8 mirror for facades, handrails, balustrades and cladding. Structural. 304, 316 and, for high load with chloride exposure, duplex 2205, supported by EN 1090-1 EXC2 execution and 3.1 certificates.
Cost, nickel and grade selection
Most of the cost of austenitic stainless is in the alloying, particularly nickel: 304 carries 8 to 10.5 percent nickel and 316 carries 10 to 13 percent plus molybdenum, which is why 316 costs more than 304 and why the price of both moves with the nickel market. The practical rule is to specify the lowest grade that meets the corrosion duty: 304 for general and dry work, 316L only where chlorides demand it. Where strength as well as corrosion resistance is needed, duplex 2205 uses less nickel than 316 while offering higher strength, which can make it competitive on a whole-life basis.
Stainless versus galvanised steel and aluminium
Stainless steel is chosen where corrosion resistance, hygiene, temperature or appearance justify its cost. Galvanised steel is cheaper for structural and outdoor work where a zinc coating handles corrosion, but it does not suit food, chemical or high-temperature use. Aluminium is lighter and needs no coating but is softer and less heat-resistant. Stainless wins for food and pharmaceutical surfaces, chemical exposure, high temperature and visible architectural work. ULAMEX supplies all three, including galvanised steel and aluminium, so a project can select and source the right material from one supplier.
Why source stainless steel from ULAMEX
ULAMEX has supplied steel and aluminium to professional buyers since 1988, more than 38 years in the trade. The stainless range is built around the grades fabricators actually order, with the documentation that food, pharmaceutical and structural customers require.
| What you get | Detail |
|---|---|
| Grades | 304, 304L, 316L, 316Ti, 430 and duplex 2205, in profiles, sheet, rods and pipes |
| Certification | EN 1090-1 EXC2 and ISO 3834-2; 3.1 certificate per EN 10204 on request, batch-traceable |
| Lead time | Typically 2 to 7 working days on stocked lines; same-day dispatch on established accounts |
| Order flexibility | No minimum order quantity on stocked SKUs; mixed pallets standard |
| Single source | Stainless with aluminium and structural steel on one order, one invoice |
Need stainless steel for a project? Send your grade, form, finish and dimensions, and ULAMEX will return a non-binding quotation with current availability, lead time and pricing. Browse the full stainless steel range, or contact the export desk at [email protected] or +48 504 424 761. For our full range, certification and quote process, see steel and aluminium supply capabilities.
Frequently asked questions
What is the difference between 304 and 316 stainless steel?
316 adds 2 to 2.5 percent molybdenum to the 304 composition, which significantly improves resistance to chlorides and aggressive chemicals. Use 304 for general and dry environments, and 316 (316L) for coastal, marine, chemical and pharmaceutical exposure.
What is the difference between 316 and 316L?
316L is the low-carbon version of 316, with carbon capped at 0.030 percent. The lower carbon avoids carbide precipitation at welds, so 316L is the safe choice for welded fabrication. ULAMEX stocks 316L (1.4404) as standard.
Is stainless steel magnetic?
The austenitic grades (304, 316, 316Ti) are generally non-magnetic when annealed, though cold working can induce slight magnetism. Ferritic 430 is magnetic and duplex 2205 is weakly magnetic. A magnet is a rough sorting aid, not a reliable grade test.
Which stainless grade is best for marine or coastal use?
316L (1.4404) is the standard choice for coastal, marine and chloride exposure thanks to its molybdenum content. For the most severe marine and high-load duty, duplex 2205 (1.4462) provides the highest corrosion resistance.
Is stainless steel food-safe?
Grades 304 (1.4301) and 316L (1.4404) are approved for direct food contact under EU Regulation 1935/2004. A 2B or BA finish gives the smooth, non-porous surface needed for hygiene, and 316L is preferred where chlorides or acidic media are present.
What are V2A and V4A?
They are the German designations: V2A is grade 304 (1.4301) and V4A is grade 316L (1.4404). V4A, with molybdenum, is the more corrosion-resistant of the two.
What surface finishes does ULAMEX offer?
2B (standard cold-rolled), BA (bright annealed, for hygiene), No.4 (brushed satin) and No.8 (mirror). Specify the finish on the order line, as it is set at the mill and confirmed on the dispatch note.
Can ULAMEX supply a 3.1 certificate for stainless steel?
Yes. An EN 10204 Type 3.1 inspection certificate is available on request for all stainless products, confirming chemical composition and mechanical properties. Each certificate is batch-traceable and assigned per shipment, so specify it when ordering. ULAMEX operates EN 1090-1 EXC2 and ISO 3834-2.
What forms of stainless steel does ULAMEX stock?
Profiles (angle, channel, flat bar, sections), sheet (smooth, perforated, tear plate), rods (round, square, hexagonal) and tube and pipe, in 304, 304L, 316L, 316Ti, 430 and duplex 2205. All are available with no minimum order quantity on stocked SKUs.
What filler metal is used to weld 304 and 316 stainless?
The filler matches the base grade: 308L for 304 and 316L for 316. The low-carbon L grades and matching low-carbon fillers avoid carbide precipitation at the weld, which protects corrosion resistance in welded fabrication.
Why does stainless steel rust?
Usually from surface contamination with free iron (from carbon steel tools or storage) or from chlorides that break down the passive layer and cause pitting, especially on 304 in coastal environments. Choosing 316L or duplex for chlorides, keeping stainless away from carbon steel, and passivating the finished part prevent it.
Why does 316 cost more than 304?
316 carries more nickel (10 to 13 percent versus 8 to 10.5 percent) plus 2 to 2.5 percent molybdenum, and nickel is the main cost driver in austenitic stainless. Specify 304 for general work and 316L only where chlorides demand it; duplex 2205 uses less nickel and can be competitive where strength is also needed.