Werkstoff Numbers Explained: Reading 1.xxxx Material Numbers

What the number is

A Werkstoff number (W.Nr., material number) is a registry code from the German DIN system, now used across Europe alongside EN grade names. A grade usually carries both identities: 1.4301 is the number, X5CrNi18-10 the descriptive EN name, and "304 type" its informal label. The number itself encodes the material class and a family group, but not the exact chemistry — grades in the same group can differ in important details.

Anatomy of 1.4301

• The first digit is the material main group: 1 = steel and cast steel. Other main groups cover non-ferrous metals, for example 2 = copper alloys and 3 = aluminium alloys.
• The next two digits form the steel group number (00–99), a family classification fixed when the grade was registered.
• The last two digits are a serial within the group. They carry no composition meaning by themselves, although low numbers often mark older, long-established grades.

The groups you will actually meet

Group	Typical contents	Examples
1.00xx–1.09xx	Basic and structural carbon steels	1.0038 (S235JR), 1.0570 (S355J2)
1.10xx–1.19xx	Unalloyed quality steels	1.1191 (C45E)
1.20xx–1.28xx	Tool steels	1.2379 (D2 type), 1.2344 (H13 type)
1.33xx	High-speed steels	1.3343 (M2 type)
1.40xx–1.49xx	Stainless and heat-resistant steels	1.4301 (304 type), 1.4404 (316L type)

Alloyed engineering steels sit largely in groups such as 1.17xx and 1.18xx (1.7131 = 16MnCr5, 1.7225 = 42CrMo4, 1.8159 = 51CrV4), but the system grew historically rather than by a clean taxonomy: 34CrNiMo6, for example, is 1.6582. Treat the group as a hint about the family, and always confirm against the grade name and its governing standard.

Where the numbers show up

Werkstoff numbers dominate German-language drawings, EN 10204 mill certificates and European materials databases, where they act as the unambiguous key that descriptive names — with their spacing and spelling variants — cannot provide. Outside Europe the same grades are usually ordered by EN name or by the local equivalent, and the number serves as the cross-reference tying the identities together.

Rules of thumb

• The group tells you the family, never the full analysis. Chemistry comes from the standard the number is cited with (EN 10088 for stainless, EN 10025 for structural, and so on).
• Numbers are permanent: a grade keeps its number even when the standard is revised, which is why buyers and ERP systems prefer them — descriptive names pick up spelling variants (X5CrNi18-10 vs X5CrNi 18 10), numbers do not.
• Wrought and cast versions, and close variants, hold separate numbers. Do not assume the familiar wrought number covers a casting or a special-analysis variant.
• If a bill of materials shows 2.xxxx or 3.xxxx next to 1.xxxx items, you have left steel territory: those lines are copper- or aluminium-based alloys.