Material number 1.7131: 16MnCr5
1.7131 is the European material number (Werkstoffnummer, EN 10027-2) for 16MnCr5, alloy case-hardening steel specified in EN 10084.
What 1.7131 means
EN 10027-2 material numbers have the form 1.XXYY: the leading 1 is steel; the next two digits give the steel group (71 → Cr steels ≥ 1 % Cr); 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 1.7131 has stayed constant while the symbolic name moved from 16MnCr5 (1.7131) to 16MnCr5.
16MnCr5 at a glance
16MnCr5 is the standard European case-hardening steel for gears: 0.16 % carbon for a tough core, 1.15 % Mn and 0.95 % Cr for hardenability, Werkstoff number 1.7131, specified in EN 10084. After carburizing to 0.8 % surface carbon and quenching, the case reaches 58–62 HRC while the core stays at roughly 780–1080 MPa tensile in small sections.
It occupies the middle of the EN 10084 hardenability ladder: above C15/C16E and 16MnCr5's own lower-band variants, below 20MnCr5, 18CrNiMo7-6 and the Ni-bearing grades used for large, heavily loaded gears. That makes it the economical choice for automotive gearbox gears, small pinions, camshafts, piston pins, bushings and any part that needs a hard, wear-resistant surface over a ductile core.
The usual delivery condition is +A (soft annealed) or +FP (treated to ferrite–pearlite for machining). AISI 5115/5120, JIS SCr420 and GB 20CrMn are the nearest matches; none is identical, and the differences are explained in the table.
Full data sheet for 16MnCr5 → · Equivalent grades →