Ferrous metals and cast iron
Symbols of cast iron
Cast irons are alloys of iron and carbon in quantities of more than 2%. The carbon is in the form of graphite. The European standard system for designating cast iron is based on : A symbolic designation : It is based on literal and numerical symbols distributed over a maximum of 6 positions.
A numerical designation : This is complementary to the symbolic designation. It consists of nine characters.
Symbolic designation of cast iron.
The symbolic designation must begin with 2 letters (EN), followed by a dash -, the symbol GJ and the value of the minimum tensile strength in MPa. Thus : EN-GJ L - 200 EN: Standardised cast iron G : Casting J : Cast iron L : Lamellar graphite cast iron 200 : Minimum tensile strength 200 MPa
1: Graphical structure
L Lamellar S Spheroidal M Annealed graphite (malleable) V Vermicular N Example of (hard) graphite, ledeburitic. Y Special structure, identified in the relevant product standard.
2. Microstructure or macrostructure.
A: Austenite F: Ferrite P: Perlite M : Martensite L : Ledeburite Q : Quenched T: Tempered and tempered B : Black heart W : White heart
3 Letter describing how test samples are produced
S: Sample cast separately U: Adjacent sample C: Sample taken from a casting. X: Indicator of chemical components in alloy castings.
Designation of unalloyed cast iron
Two forms of designation can be adopted. Form 1 EN - GJL - 200 S 2OO to designate the minimum tensile strength S for characteristics measured on the separately cast sample. Form 2 Indicator: hardness according to the type of test. EN-GJL -HB 152 Brinell hardness EN-GJS-HRc 35 Rockwell hardness EN-GJN-HV 340 Vickers hardness.
Designation of alloyed cast iron
Indicators: X indicates that the cast iron is classified according to its chemical composition. EN-GJN-X 350 Cr Ni Si 10-6-1.5 1 - X : Chemical composition 2 - 3.5% carbon (% carbon content multiplied by 100) 3 - 10% chromium (Cr) 4 - 6% nickel (Ni) 5 - 1.5% silicon (Si)
Numerical designation of cast iron
The numerical designation must begin with 2 letters EN , a dash - , the symbol JL and followed by a numerical code. It is still not widely used. En - JL 1030 1 EN: Standardised cast iron 2 J: Cast iron 3 L: Graphical structure 4 1030: Numerical code (number to be assigned by the material standard)Cast iron and steel grades