Building materials. The different types of cast iron.

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.


Symbolic designation of positions.


Symbolic designation of characters.

A numerical designation :
This is complementary to the symbolic designation. It consists of nine characters.


Symbolic designation of positions.


Symbolic designation of 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