UNS, Werkstoff, JIS & EN Grade Cross-Reference

What a grade cross-reference is

A designation system is a naming scheme. It gives each alloy a code within one country's or region's standards framework. The same metal gets a different code in every system, so a cross-reference works as a translation map between those codes. It doesn't promise that two codes guarantee identical composition.

The systems this chart spans:

UNS, the Unified Numbering System, pairs a letter prefix with five digits and is maintained jointly by ASTM International and SAE. `S` marks stainless steel, `N` marks nickel alloy, and `K` covers certain carbon and low-alloy steels. 316L, for instance, is S31603, while Incoloy 825 is N08825.

Germans use the Werkstoff number instead, sometimes written W.-Nr. Or DIN EN. Stainless grades take the form `1.44xx`, nickel alloys `2.4xxx`. These designations now live inside the European EN 10088 and EN 10028 standards. 316L carries the number 1.4404.

Japan's system comes from JIS, the Japanese Industrial Standards body, and splits into two prefixes. Stainless grades get `SUS`; nickel-iron-chromium alloys get `NCF`. Under this scheme, 316L becomes SUS316L. The EN name is the descriptive European name that encodes nominal chemistry, e.g. `X2CrNiMo17-12-2` for 316L. AISI numbers are the old three-digit American Iron and Steel Institute codes, 304, 316 and the like, still thrown around in conversation, though UNS has mostly taken over for ordering purposes. BS and GB cover the older British Standard and Chinese national (Guobiao) designations. We include those when a buyer still hands over a drawing marked up in one of those older systems.

Who maintains each system

Each system answers to a different governing body, and that's precisely why no one can call two codes "identical." ASTM and SAE administer UNS. The Werkstoff number and the EN names trace back to DIN and the European standards EN 10088 (stainless flat product) and EN 10028 (pressure-vessel steel). JIS codes come from the Japanese G-series standards, while AISI is the legacy US institute scheme. Each body sets its own composition limits and acceptance tests, so a cross-reference only translates the name. The specification still belongs to whichever standard you order against.

"Equivalent" does not mean "identical": the caveat that matters

A cross-reference maps nominal chemistry and the alloy's role between systems. It doesn't promise that the two codes share the same carbon ceiling, the same stabilization, or the same mechanical and acceptance tests. A grade marked with `≈` in the table below is a nominal or nearest equivalent, not a drop-in substitute. Before treating two codes as interchangeable, read the governing specification. What the alloying elements do decides whether those small differences matter for your service.

The distinction the industry keeps strict is between two separate predicates:

• conformsTo, the grade meets a named standard, for example 316L conforming to ASTM A240 or ASME SA-240. This is what you actually buy to.
• equivalentTo, the grade's name in another designation system. This is only a translation.

When an equivalent is safe, and when it isn't

• Carbon ceiling (the L grades). 304 and 304L share the Werkstoff pair 1.4301 and 1.4307, and 316 and 316L share 1.4401 and 1.4404. The L grades cap carbon at ≤0.03%, though, to resist sensitization in the weld heat-affected zone. Don't swap a standard grade for its L partner on a welded fabrication held at 425–815 °C without checking the carbon value on the certificate.

• Stabilized grades. 321 (Ti-stabilized) and 347 (Nb-stabilized) resist intergranular attack through a different mechanism than the L grades do. They aren't freely interchangeable with 304/316, even where the base chemistry looks close.

• Dual-certified plate. Material supplied as 304/304L or 316/316L meets both the standard and the low-carbon limit on the same heat. That makes it genuinely usable either way, and the certificate proves it.

• Pressure-vessel steels. A516 Gr 70 maps to EN P355GH and JIS SGV480 by property class, not identical chemistry. These are matched on strength and pressure duty, and that's exactly why they carry the `≈` marker.

Master equivalents table: stainless, nickel alloys & PVQ

The table below sorts out the UNS, Werkstoff, JIS, EN and governing ASTM/ASME designation for every grade in the Nandini Steel catalog, and all of it sits ex-stock, ready to ship right away. A `≈` flags a nominal or nearest equivalent in cases where that system has no exact one-to-one code.

Austenitic stainless

Super-austenitic & duplex

UNS N08904, 904L, Werkstoff 1.4539, EN X1NiCrMoCu25-20-5, the old BS 904S13, there's no exact JIS equivalent, though SUS890L comes closest. Buyers working across standards end up translating that full designation set more than almost any other row. 904L also sits within Nandini Steel's ISO 9001 certified specialty scope.

Nickel & Ni-Fe-Cr alloys

Alloy 20 and Hastelloy C22 have no established JIS designation, so those cells carry a dash instead of a forced match. Incoloy 800 and Hastelloy plates also sit on Nandini Steel's certified specialty scope, alongside 904L and Alloy 28 / Sanicro 28.

PVQ & Cr-Mo steels

Every pressure-vessel row carries a `≈` mark. ASTM A516 and its EN and JIS counterparts line up by property class, meaning tensile range and pressure duty, not by identical chemistry. Check the governing ASTM A516 grade and plate thickness on the order itself. Don't lean on the nominal EN or JIS code.

How to read each designation

Once you know the format rules, most codes decode themselves.

Why Incoloy 825 is not an Inconel

The most common designation error buyers make is writing "Inconel 825" on a purchase order. The correct name is Incoloy 825, a nickel-iron-chromium alloy, UNS N08825, Werkstoff 2.4858, conforming to ASTM B424 / SB-424, which is a different alloy family from the Inconel nickel-chromium grades. Inconel and Incoloy are trade names, not designation systems; the UNS number is what fixes the identity. Getting the designation right on the PO and the certificate avoids receiving-inspection disputes, and for sour service the order should also cite NACE MR0175 / ISO 15156 so the heat is supplied in the qualified condition. When a drawing or PO and the mill paperwork disagree, the UNS number and the heat chemistry settle it, a mix-up Nandini's team routinely catches before dispatch.

How the grade appears on the Mill Test Certificate

A cross-reference tells you what to call the grade; the certificate proves what you received. An EN 10204 3.1 mill test certificate states the ordered specification, the grade, and the heat or cast number, with the measured chemistry and mechanical results for that heat. Positive material identification (PMI) confirms the chemistry on the physical plate, it reads the elements, not the trade name or the system code, so PMI plus the MTC together verify that the designation on the paper matches the metal. Dual-certified material (304/304L, or an ASTM-plus-EN certificate) is called out explicitly on the document. For the full workflow, see how to read a mill test certificate and PMI and MTC testing.

Nandini Steel includes EN 10204 3.1 / 3.2 mill test certificates with every order, and the plate comes from genuine mills, names like Aperam, Outokumpu, Jindal, POSCO, Nippon Steel and JFE.

How to order to the right grade

Translate the designation, then order it to a specified grade rather than settle for a nearest equivalent.

1. Translate the drawing code to its UNS number using the master table. This fixes the alloy identity across systems.
2. State the governing standard and grade, for example ASTM A240 316L or ASME SA-240 316L, not "1.4404 equivalent."
3. Add the UNS number (S31603) on the PO as the unambiguous identity check.
4. Specify the form and dimensions, plate, sheet, coil, thickness and size.
5. Name the MTC level, EN 10204 3.1 or 3.2, and spell out any extra tests the service calls for, whether that's PMI, Charpy, or HIC per NACE TM0284.

Head for the exact page for whichever grade you're after: 304 stainless, 316 / 316L, 904L (UNS N08904), Incoloy 825 (N08825), and A516 Gr 70 (K02700). Still weighing your options? The grade selector narrows the field by service conditions, and the weight calculator turns your chosen form and size into a dispatch weight.

Frequently asked questions

Request a quote or the correct grade certificate

Nandini Steel's team will confirm the correct standard, grade and UNS number once you give them the drawing code, the service and the form, and they'll ship it ex-stock with an EN 10204 3.1 / 3.2 mill test certificate. Every grade listed above sits ready for immediate dispatch, so ask for a quote to get live pricing.

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