Material number 1.0301: C10
1.0301 is the European material number (Werkstoffnummer, EN 10027-2) for C10, unalloyed low-carbon case-hardening steel specified in EN 10084.
What 1.0301 means
EN 10027-2 material numbers have the form 1.XXYY: the leading 1 is steel; the next two digits give the steel group (03 → steels with < 0.12 % C or Rm < 400 MPa); the last two digits are a sequential number within that group. The number is unique to one composition and survives name changes, which is why 1.0301 has stayed constant while the symbolic name moved from Ck10 to C10.
C10 at a glance
C10 is the lowest-carbon case-hardening steel in EN 10084: 0.07–0.13 % carbon, 0.3–0.6 % manganese, Werkstoff number 1.0301 (base) or 1.1121 for C10E, the old Ck10. Its very soft core (≈ 110–140 HB normalized) and outstanding cold formability make it above all a cold-heading and deep-drawing steel — screws, rivets, clevis pins, small bushes and drawn cups — that can afterwards be carburized to a 55–60 HRC skin where wear resistance is needed.
Because hardenability is minimal, the case is thin and only small parts are treated; for anything larger or more highly loaded, C15E or 16MnCr5 take over. Un-carburized C10 is also a general low-carbon bar and tube steel comparable to AISI 1010.
A note on names: searches for 'C8 steel' and 'C12 steel' almost always mean the cold-heading wire grades C8C and C12C of EN 10263-2, or simply a 0.08–0.12 % C steel — there is no separate C8 or C12 grade in EN 10084. C10/C10E is the grade to order.
Full data sheet for C10 → · Equivalent grades →