Grades & Standards Reference
Stainless Steel Grades
Stainless grades differ by their chromium and nickel (and sometimes molybdenum) content, which sets their corrosion-resistance class and the series they belong to — use the mapper below to narrow the range to one or two grades before you request a quote.
Information date:
Definition & boundaries
What counts as a stainless grade here — and what does not
On this page a stainless steel grade is a chromium-bearing corrosion-resistant alloy of 300, 400 or duplex/precipitation series. Carbon and alloy grades are routed elsewhere, not blurred in.
In scope
The 300 series (304, 316, 321), the 400 series (430, 410) and duplex / precipitation grades (2205, 17-4 PH), each with its EN material number and governing standard.
Out of scope
Carbon steel grades and alloy steel grades are not covered here. They belong to their own routes, not to this stainless comparison.
How it is bounded
A grade is identified by its AISI designation and EN material number together, so a nickel or molybdenum difference — 304 vs 316 — is never collapsed into one bucket.
Product Mapper
State the application, exposure and need — get the grade
Three inputs return the matching stainless grade(s) with their real composition and EN/AISI standard reference. No generic fallback.
Not sure of the exposure or grade? Send it for review.
Request Quote
Surface finish is part of the grade decision, not an afterthought.
The full stainless range
The mapper covers the grades listed in the definition above. The full table of designations with their EN material numbers sits just below.
Cross-product mapping
If stainless is not the fit, jump to a sibling family
A comparison table that routes you to the neighbouring grade family rather than a dead end.
| Grade family | What it covers | Link |
|---|---|---|
| ASTM Steel Grades | American material designations across the range. | View |
| EN Steel Grades | European EN material numbers (1.4401, 1.4301 …). | View |
| API Steel Grades | Line-pipe and oilfield grades. | View |
| Carbon Steel Grades | The carbon equivalents for non-stainless use. | View |
| Steel Specifications | How a specification is written and verified. | View |
| Knowledge Center Hub | Background reading, size charts and comparisons. | View |
Selection criteria
The four factors to weigh before you fix a grade
Corrosion environment, temperature, weldability and cost are the levers. Each pulls the choice toward a different grade.
Corrosion environment
Coastal, chloride or chemical exposure pushes the choice toward molybdenum-bearing 316 or duplex 2205.
Temperature
Elevated temperature favours the titanium-stabilised 321 against intergranular corrosion.
Weldability
Heavy welding benefits from a stabilised or low-carbon grade to hold corrosion resistance at the weld.
Cost
Chromium and nickel content drives cost; a ferritic 430 can be the lower-cost alternative where finish allows.
Applications & limits
Where stainless is the right choice — and where it is not
Stainless earns its place where corrosion resistance is non-negotiable. It is honest about its cost and size-availability constraints too.
Right choice when
- — Food, marine, chemical or coastal service where corrosion ruins carbon steel.
- — Hygiene or finish requirements that rule out a coated carbon alternative.
- — High-temperature or welded service needing an austenitic or stabilised grade.
Not the right choice when
- — Corrosion resistance is not required — a carbon grade is the cheaper fit.
- — A specific size or surface finish has limited stainless availability.
- — Budget dominates and the environment is mild.
Constraints to confirm
- — Size and surface finish availability for the exact grade.
- — The molybdenum premium, which rises with grade 316 and duplex.
- — Magnetic versus non-magnetic expectation at the point of use.
Evidence-based advantages
Buyer concern → provable capability → outcome
Four cards; each rests on a verifiable control, not a statistic.
Grade delivered is not the grade ordered
The stainless grade is tied to its EN material number (e.g. 1.4401) and verified against the governing standard before release.
A 316 order cannot be swapped for 304 without the certificate showing it.
Wrong grade for the environment
The mapper asks for corrosion exposure first, so chloride or chemical exposure is matched to a molybdenum-bearing grade.
A coastal or chemical requirement is not routed to a baseline 304.
Intergranular corrosion after welding
Elevated-temperature and heavy-weld needs are steered to the stabilised 321 grade where it matters.
A high-temperature joint is carried by a grade built for it, not an unstabilised baseline.
Availability in the size you need
Grade, dimensions and standard are reconciled together — size and surface finish are part of the check, not an afterthought.
The enquiry is quotable in one pass rather than reopened for a missing size.
Expert insight
Match the grade to the chloride, not to the shape
A corrosion-class guideline: the single factor that most often decides between 304 and 316 is the presence of chlorides.
Method & source
This guideline is a reading of the stainless steel selection and corrosion guidance published by the World Steel Association (worldsteel), which describes how molybdenum additions to austenitic grades improve resistance to pitting from chlorides. The method is a reading of that guidance, not a reproduction of it.
Information date:
Chlorides decide 304 versus 316
The practical split point between 304 and 316 is chloride exposure. Plain atmospheric and fresh-water service is met by 304; coastal, marine or acidic service introduces chlorides that attack the passive layer, which is exactly what the molybdenum in 316 resists. Specifying the grade from the environment first — rather than the shape — is what prevents an under-specified 304 from failing early on a marine handrail or a chemical vessel.
Ask "is there chloride here?" before you ask "what size is it?"
Stainless pipe and tube — the grade must match the fluid it carries.
From enquiry to delivery
Ten steps after you have picked your grade
Written for a visitor who has just identified their grade and is ready to take it through the order.
Requirement or need
Owner: BuyerInputApplication, environment, mechanical need
Verification riskUnstated corrosion environment
OutputA grade requirement in plain terms
Next: Send to specification intake
Specification intake
Owner: Commercial teamInputGrade, EN material number, dimensions
Verification riskGrade stated without its EN number
OutputRequirement captured against a standard
Next: Hand to technical review
Technical review
Owner: Technical reviewInputGrade and standard cross-check
Verification riskGrade/environment mismatch
OutputConfirmed grade and standard
Next: Move to quotation
Quotation
Owner: Commercial teamInputScope and terms
Verification riskUnfixed quantity or surface finish
OutputPrice on request and terms
Next: Await confirmation
Order or contract
Owner: Buyer + commercialInputConfirmed order and documents
Verification riskUndocumented verbal change
OutputOrder and document list
Next: Trigger quality checks
Quality and document checks
Owner: Warehouse / QAInputCertificate and material conformity
Verification riskCertificate not tied to heat
OutputConformity confirmed
Next: Pack order
Packing
Owner: WarehouseInputPick list and packing method
Verification riskSurface finish damage
OutputBundled, protected, edge-guarded
Next: Ship
Shipping
Owner: LogisticsInputDocument pack and route
Verification riskIncomplete document pack
OutputLoad released with documents
Next: DeliverMarkets Hub
Delivery
Owner: LogisticsInputDestination and access
Verification riskUnconfirmed site access
OutputDelivery note countersigned
Next: Close outMarkets Hub
After-sales
Owner: Commercial teamInputDiscrepancy record
Verification riskLate-reported discrepancy
OutputResolution with carrier and buyer
Next: Resolve any open item
FAQ
Stainless grade selection, answered directly
What is the difference between 304 and 316 stainless steel?
316 adds molybdenum (roughly 2–3%), which gives it better chloride and pitting resistance than 304. Choose 316 where salt, coastal or chemical exposure is a factor; 304 is the baseline for general and food-contact service.
Is stainless steel food-grade and safe for food contact?
304 (1.4301) and 316 (1.4401) are both widely used for food-contact equipment. 316 is preferred where salt or acidic cleaning is involved because of its molybdenum content.
Why are some stainless grades magnetic and others not?
It comes down to crystal structure. Austenitic grades (304, 316) are non-magnetic in the annealed state, while ferritic (430) and martensitic (410) grades, and duplex, are magnetic.
How much more does stainless cost than carbon steel?
Stainless costs more than carbon steel because of its chromium and nickel content. The exact premium is on request and depends on grade, form and quantity — the page does not display a fixed price.
Which grade handles chloride or marine exposure?
A molybdenum-bearing grade — 316 (1.4401) for general service, or duplex 2205 (1.4462) where high strength is needed alongside chloride resistance.
Which grade should I use for high-temperature or welded service?
321 (1.4541) is titanium-stabilised against intergranular corrosion, making it a common choice for elevated temperature and heavy welding.
How do I confirm the exact grade and standard I need?
State the grade and its EN material number or standard, then send it for review. The technical team cross-checks the grade against the environment before release.
Request a Quote
Name the grade, EN material number, dimensions, surface finish, quantity and destination, and the commercial team reconciles it against the governing standard.
Serving GCC buyers and export destinations