When working with stainless steel, you inevitably encounter scenes like this: the warranty states X6CrNiMo17-12-2, the contract says 1.4404, and the customer calls it '316L.' In fact, these are not three different types of steel, but three 'languages' for the same material. This article will help you decode the 'steel codes' of European standard stainless steel, so that next time you see these grades, you'll understand them and can speak confidently about them.

I. Two "ID Cards" for Stainless Steel in Europe

In the European standard system, stainless steel typically has two "ID cards":

Kurznamen: A "short name" consisting of letters and numbers.

Examples: X6Cr17, X6CrNiMoTi17-12-2, X9CrNiSiNCe21-11-2.

It is more commonly used by technicians, as the name gives a rough idea of the composition and type.

Werkstoffnummer: Material number.

Examples: 1.4016, 1.4301, 1.4571, 1.4404.

The structure is 1.XXXX, where "1" represents "steel and steel castings," and the following digits indicate grouping and serial numbers.

Stainless and heat-resistant steels generally fall within the 1.40xx–1.49xx range.

In simple terms:

For on-site communication and analyzing chemical composition trends, the X…CrNi… short name is used.

For standard comparisons, databases, and material selection software, the 1.4xxx material number is more common.

II. Understanding "X6Cr17": How to Read This Short Name?

Taking X6Cr17 (material number 1.4016) as an example:

Starting with X: This indicates a high-alloy / stainless steel.

Most stainless steel plates, bars, and similar products have names starting with X.

Meaning of X: This is alloy steel, with at least one alloy element having a mass fraction ≥ 5%.

For stainless steel, this "≥5%" element is typically chromium (Cr), and the basic requirement for stainless steel is Cr ≥ 10.5%.

What Does "6" Represent for Carbon?

The number immediately following X represents:

Average carbon content (mass fraction %) × 100.

So: 6 means approximately 0.06% C; if it were 3, it would be 0.03% C; if it were 90, it would be 0.90% C.

Now you know: X6… is a high-alloy steel with about 0.06% carbon.

What Are Cr, Ni, Mo… These Letters For?

The string of uppercase letters represents the chemical symbols of the main alloying elements:

Cr (chromium), Ni (nickel), Mo (molybdenum), Mn (manganese), N (nitrogen), Cu (copper), etc.

Arrangement rules: Generally in descending order of content; if contents are similar, they are listed alphabetically.

So X6Cr17 indicates: This is a steel where Cr is the main alloying element, with other alloying elements either low in content or not "significant" enough to be included in the name.

What Does the Final Number "17" Mean?

In Cr17, the 17 is the rounded average mass fraction of that element:

Cr17 ≈ 17% chromium; if written as Ni10, it roughly means 10% nickel.

So X6Cr17 can be translated into plain language:

"This is a high-alloy stainless steel with approximately 0.06% carbon and 17% chromium."

Let’s look at a slightly more complex example: X6CrNiMoTi17-12-2 (material number 1.4571).

Breaking it down:

X: High-alloy steel / stainless steel.

6: Carbon content ~0.06%.

CrNiMoTi: Main alloying elements in order: chromium, nickel, molybdenum, titanium.

17-12-2: Approximately 17% Cr, 12% Ni, 2% Mo.

Ti: A stabilizing element, typically in the range of 0.2–1.0%, indicated by Ti but usually without an additional number.

Plain language translation:

"A molybdenum-containing, titanium-stabilized 17Cr-12Ni-2Mo stainless steel, similar to the familiar 316Ti type."

III. G, PM, and "Tail Numbers": Additional Hints

Besides the X6… structure, European standard names may include prefixes or suffixes to provide additional information:

Prefix G: Steel casting.

Example: GX5CrNi19-10 — the appearance of "G" indicates this is a stainless steel casting, not ordinary rolled plate or bar.

Prefix PM: Powder metallurgy steel.

Commonly used for tool steels, high-speed steels, etc., indicating preparation via powder metallurgy.

Less common in conventional stainless steel plate/coil trade but encountered in high-end knives and molds.

Numbers After Elements: "Trace Elements" at 0.2–1.0%

Some names may include notations like N2 or Cu3:

The number is usually the rounded value of the element's content (mass fraction %) × 10.

For example: N2 corresponds roughly to 0.2% nitrogen; Cu3 corresponds to 0.3% copper.

If the content is very low, only the element symbol may be written without a number.

These "tails" are crucial when selecting high-end materials or checking certificates, especially for confirming stabilizing or strengthening elements like Ti, Nb, or N.

IV. Understanding "1.4404": What’s the Logic Behind Material Numbers?

Having discussed short names like X6CrNiMo17-12-2, let’s look at the other system: Werkstoffnummer (material number).

Taking 1.4404 as an example:

First Digit: "1" Represents Steel

The first digit of the material number indicates the material category:

1: Steel and steel castings.

2: Heavy metals (e.g., Ni, Co).

3: Light metals (e.g., Al, Mg, Ti).

…

Seeing 1.XXXX confirms it’s steel, not a copper or aluminum alloy.

Middle Two Digits: "44" Represents Stainless Steel with Ni + Mo

For the steel category, the second and third digits divide it into subgroups. Stainless and heat-resistant steels are generally grouped within 40–49:

40: <2.5% Ni, no Mo, Nb, Ti (e.g., 1.4016).

41: <2.5% Ni, contains Mo.

43: ≥2.5% Ni, no Mo, Nb, Ti (e.g., 1.4301).

44: ≥2.5% Ni, contains Mo (e.g., 1.4404).

45: Stainless steel with "special additions" like Nb, Ti (e.g., 1.4571).

47/48: Heat-resistant steel.

So, when you see 1.44xx, you should instinctively think:

This type belongs to the "nickel- and molybdenum-containing" austenitic stainless steel family, generally offering better pitting resistance than the 1.43xx group.

Last Two Digits: "04" Is the Serial Number Within the Group

Within the same subgroup (e.g., 44), the last two digits act like serial numbers:

Ranging from 00–99.

If a group uses up 100 numbers, it expands into forms like 9901.

Important note: In the European standard system, once a material number is assigned to a specific steel, it cannot be reused for another steel type.

This means that as long as you see 1.4404, this number has always corresponded to the same set of chemical compositions and performance ranges, greatly facilitating database management and cross-standard comparisons.

V. Why Are These Two "Codes" Essential in Engineering and Trade?

Many people think material names are only "for engineers," but they are equally important for those in trade, procurement, and technical support.

Clearer Cross-Language Communication

Real-world scenario:

An American client says: "We need 316L."

A Japanese drawing says: SUS316L.

A European drawing says: 1.4404 / X2CrNiMo17-12-2.

If you only know "316L," you might struggle with cross-standard substitutions.

If you are familiar with material numbers and European short names, you can quickly determine:

Are they from the same system? Are the performance levels similar? Can they be directly substituted?

More Informed Material Selection and Substitution

Just by looking at material numbers:

1.4301: Belongs to the 43 family, has Ni, no Mo (similar to 304).

1.4404: Belongs to the 44 family, has Ni, has Mo (similar to 316L).

You’ll know: You shouldn’t casually substitute 1.4301 for 1.4404 in high-chloride environments, as the risk of pitting and crevice corrosion is higher.

Looking at short names:

X2CrNiMo17-12-2: Contains Cr, Ni, Mo—the three key elements—indicating better corrosion resistance and higher cost compared to ordinary Cr-Ni steels.

If you see N (nitrogen) or Cu (copper), you can infer whether the steel leans toward high strength, reprocessing resistance, crevice corrosion resistance, or resistance to sulfuric acid or organic acids.

More Rigorous Certificate and Procurement Inspection

On a certificate, you might see a combination like:

Material number: 1.4404.

Designation: X2CrNiMo17-12-2.

Equivalent: ASTM A240 316L.

If you are familiar with all three "languages," you can:

Quickly verify whether the supplied material meets the drawing and contract requirements.

Quickly identify if "304 is being sold as 316" or "316Ti is being sold as 316L."

Quickly reach consensus with clients and suppliers from different countries.

VI. Handy Cheat Sheet (Copy This to Your Notebook)

Here’s a "cheat sheet" you can use in practice:

European Short Name (Kurznamen)

Basic structure: X + carbon number + element letters + element content numbers.

Key points:

X: High-alloy / stainless steel.

First number: C × 100 (6 → 0.06% C).

Element letters: Cr, Ni, Mo, Mn, N, Cu, etc.

Tail numbers: Approximate rounded content of each element (integer %).

Examples:

X6Cr17 ≈ 0.06% C, 17% Cr.

X2CrNiMo17-12-2 ≈ 0.02% C, 17% Cr, 12% Ni, 2% Mo.

Material Number (Werkstoffnummer)

Basic structure: 1.4xyz (for stainless and heat-resistant steels).

Key points:

40: Low Ni, no Mo.

43: Has Ni, no Mo.

44: Has Ni, has Mo.

45: Contains special elements like Nb/Ti.

First digit "1": Steel and steel castings.

"40–49": Stainless / heat-resistant steel family.

Last two digits: Serial number within the family (like a license plate).

Examples:

1.4016 → X6Cr17 (ferritic stainless steel, no Ni, has Cr, no Mo).

1.4301 → X5CrNi18-10 (classic 304).

1.4404 → X2CrNiMo17-12-2 (classic 316L).

1.4571 → X6CrNiMoTi17-12-2 (316Ti, Ti-stabilized).

VII. Summary: How to Quickly "Translate" European Designations

You can follow a three-step process:

Check the material number:

1.43xx: Ordinary Cr-Ni type (304 family).

1.44xx: Cr-Ni-Mo type (316 family).

1.45xx: 43/44 types with added stabilizing elements like Ti/Nb.

Examine the element combination in the short name:

Does it have Mo? Those with Mo generally have better pitting resistance.

Does it have N? Those with N usually have higher strength and different welding properties.

Does it have Cu? Often related to resistance to certain acidic media.

Match to the application scenario:

Potable water, general architectural decoration: 1.4301 level.

Coastal areas, light chemical corrosion, chloride-containing environments: Prefer 1.4404/316L level.

High-temperature, pickling lines, flue gas desulfurization, and other harsh environments: Look toward higher grades like duplex steels or super-austenitic steels.

When you get used to "decoding" European designations this way, the X6CrNiMo17-12-2 on a drawing, 1.4404 in a contract, and 316L mentioned by a client will no longer be three confusing languages but three mutually verifying "ID cards."

The next time you encounter a long, unfamiliar European designation, stare at it for three seconds, break it down using the rules above, and you’ll find: They’re not so scary after all—they just need someone to translate them into understandable language.