Symbolic designation (standard NF EN 10027-1)
The manufacturing and naming of steels

Main symbols

The main symbols summarized in table 2 are followed by the guaranteed minimum yield strength in N/mm 2 for the lowest thickness range.

Additional symbols for structural steels

Structural steels are symbolized by the letters J, K or L to give resiliencies of 27, 40 or 60 joules respectively. These letters are followed by a number from 0 to 6, corresponding to test temperatures of 0, 20, 30, 40, 50 and 60°C respectively.

The letter R is given only for the temperature of +20°C, which may be followed by a W to indicate resistance...