Page 96 - 20250602 EEA QM Edition 6.0

Quality Requirements Edition 6.0 European Enamel Association

The silicon content plays an important role. Low silicon contents, below 2.5 %, are
8.0 EEA-SPECIFICATIONS
slowing down the ferritization process so that it is not finalized after the enamelling

process has been completed. An elevated outgassing, due to the conversion of perlite,
8.1 Cast iron, suitable for enamelling causes pores and pin holes during the final stage of firing.

8.1.1 Cast iron with lamellar graphite complying to DIN EN 1561 (grey cast Because of the perlite stabilizing effect, manganese contents more than 0.45 % should
iron) be avoided. They lead to an embrittlement and to a formation of strong stresses in the
composite material cast iron / enamel.
Chemical analysis:

Particularly critical for the enamelling are the trace elements Chromium, Molybdenum,
The following limiting values of the main elements should be kept:
Nickel, Titanium and Vanadium if the above-mentioned maximal concentrations are
a) Carbon, total C 3.20 - 3.40
exceeded. Consequently, the perlite is that much stabilized, that only an incomplete
b) Carbon, combined C max. 0.20 composition to ferrite takes place during enamelling. It leads to a fluctuating expansion
c) Silicon Si 2.50 - 3.25 behaviour of the casting, depending upon its wall thickness.
d) Manganese Mn max. 0.45
e) Phosphorus P 0.25 - 1.00 The Sulphur content is in particular to consider by applying the wet enamelling process
f) Sulphur S max. 0.12 for cast iron. Sulphur contents up to max. 0.12 % in general do not cause defects.

Trace elements: Higher Sulphur contents can lead to severe difficulties in the enamelling because of the
diffusion of Sulphur towards the cast iron surface. During the hot process the velocity of
g) Chromium Cr max. 0.05 oxidation is that much increased, that the thereby formed quantities of iron oxide cannot
h) Copper Cu max. 0.10 be absorbed by the enamel.
i) Molybdenum Mo max. 0.05

j) Nickel Ni max. 0.10 The formation of stresses within the composite system cast iron / enamel is mainly,
k) Titanium Ti max. 0.05 under consideration of different designs, a matter of the structure of the cast iron. After
the casting process the structure must be Perlitic, not Cementitic.
l) Vanadium V max. 0.05

m) Tin Sn max. 0.10
For the enamelling process the surface of the cast iron has to be clean and free of
n) Sum Cr + V + Ti max. 0.12
burned- in sand. Its medium roughness should not exceed 300 microns.

Saturation value: Sc = min. 1.04 max. 1.08

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