SUPERSEED® INOCULANT - Elkem

2. Less fading
The increase in eutectic cell numbers
created by inoculation may be regarded
as a supersaturated condition which
fades rapidly with time. Inoculants
giving very high eutectic cell numbers
will fade more rapidly and it is therefore
necessary to cast the metal within
a very short time after inoculation in
order to gain the full benefit of the
addition. Because Superseed ® inoculant
gives a lower eutectic cell number
for the same degree of chill control,
fading is slower and the properties of
the treated iron remain more constant
over a longer period of time. This is illustrated
diagrammatically in Figure 5.
Limitations of Superseed® inoculant
Superseed ® 75 and Superseed ® 50
inoculants are very effective in grey
iron with base sulphur content above
about 0.05%. At or below this level,
other Elkem inoculants may be more
effective.
Figure 5: Fading characteristics of
Superseed ® inoculant and FG FeSi.
Superseed ® Inoculant in Ductile Iron
Superseed ® inoculant is extremely
effective for the inoculation of high
purity ferritic ductile iron not requiring
cerium to give good graphite nodularity.
Eutectic carbide is eliminated
from thin sections and the very high
nodule numbers pro duced promote
the formation of fully ferritic structures
as-cast, thus reducing the need for heat
treatment. Many foundries also find
Superseed ® inoculant to be effective
in less pure ductile irons requiring a
small addition of cerium, although
there is some evidence to suggest that
excess cerium reduce the effec tive -
ness of Superseed ® inoculant. In these
circumstances it is recommended that
an alternative inoculant from the Elkem
range is used.
Application of Superseed ® Inoculant
Elkem supply the different ladle
and metal stream inoculation (MSI)
gradings of Superseed ® inoculant
upon customer request and with
certified analysis.
As to ladle inoculation, most foundries
find the amounts of Superseed ®
inoculant required to give adequate
chill control lie between one-half and
two-thirds of other inoculants. The
alloy should be added to the tapping
stream as the ladle is filled or, preferably,
as the metal is transferred from
a supply ladle to the casting ladles.
Superseed ® inoculant should NOT
be dumped into the bottom of a ladle
before filling starts.
With metal stream inoculation, the
power ful inoculating action and the
clean solution characteristics of
Superseed ® inoculant are ideally
suited to this method of inoculation
that is increasing in use in many larger
mass production foundries. Addition
rates are usually 0.1% or less for grey
iron and around 0.15% for ductile iron.
This allows the silicon content of the
base irons to be increased significantly
with the associated advantages of
better scrap utilisation and reduced
lining wear in coreless induction
furnaces.
Elkem AS
Foundry Products
Hoffsveien 65B
P.O. Box 5211
Majorstuen
N-0303, Oslo, Norway
Telephone : +47 22 45 01 00
Telefax : +47 22 45 01 52
www.foundry.elkem.com
Revised April 2012 © Copyright Elkem AS