The classification and nature of the nodulizer for ductile iron
Nodulizer is the primary mean of accessing to
ductile iron. This article will briefly analyze the classification
and nature of the nodulizer.
The classification of the
Divided by production of ductile iron
castings, nodulizer can be classified as alloy-like nodulizer,
massive nodulizer, core line nodulizer, power nodulizer.
1. Alloy-like nodulizer
Including Mg-Si alloy, magnesium silicon
alloy, calcium alloy (Japanese use more), nickel magnesium alloy,
pure magnesium alloys and rare earth alloy.
Currently the world's most widely used alloy is rare-earth-Mg-Si
But the ratio of rare earth divided by Mg
in China foundries ranges from 0.5 to 2.2, in foreign this ratio
ranges from 0.1 to 0.3.
1.1.1 Calcium alloy
The calcium and magnesium nodulizer is
mainly used by Japan casting producers.
The production of Shin-Etsu (SHIN-ETSU),
NC5, NCl0, NCl5, NC20, NC25, the content of magnesium changes from 4
to 28%. But there are small changes in calcium content; the range is
from 20 to 31%. Chilling tendency of such alloys is small, but it
requires a high processing temperature and large amount of residue
1.1.2 Nickel magnesium
Nickel magnesium alloys is produced by
International Nickel Company. The content of nickel is up to 82 ~
85% while Ca is 20 % and Mg is 13%-16 %. But nickel is 57 to 61%
minimum (which Mg 4 .0 ~ 4.5 %, Ca <2.5 %, Fe 32 ~ 36 %). German
chemical company produces nickel-metal magnesium alloy in which Ni
47 ~ 51 %, Mg l5 ~ 17 %, C1.0 % Si28 ~ 32 %, RE1.0 %. The advantage
of these alloys is heavy, reaction steady and nickel alloy can play
a role in alloying. But it is characterized by expensive, this alloy
in China, basically is not applied in China foundries.
1.1 Nickel-silicon alloy
Nickel-silicon alloy is currently not
applied in China basically.
1.2 Pure magnesium alloy
Pure magnesium alloy processing need a
dedicated pressure make magnesium package, and the magnesium
absorption rate is high. But it needs very strict security dealing
measures leading to a smaller proportion of the production
1.3 Rare earth
Rare earth is used when iron foundry
invented ductile iron, which promotes the process of ductile iron
industrial applications greatly.
But the price is high, and it has a large
chilling tendency. If the mount is over, it will make graphite
metamorphosis .So now it is no used alone as nodulizer, only as an
2. Massive nodulizer
Press magnesium and iron and silicon
content designed directly into compression molding. Silicon in this
nodulizer is very low. So it is referred to as a low pressure block
nodulizer, which provides subsequent room and conducive to
production of cast iron. But this alloy is easy to float, the effect
of treatment is volatile. So it is better to use with massive
3. Core line nodulizer
Coat the magnesium powder, iron powder in a
thin steel plate or steel plate and cast it into the molten iron to
achieve the purpose of balling. But this nodulizer is expensive, the
investment in equipment is large and the absorption rate of alloy is
high, so the cost of processing ductile iron is almost no increase.
4. Power nodulizer
Power nodulizer is a Russian patent. Mix
with the magnesium powder and inhibitors into the bag. Make the
molten iron flow through the surface of alloy, reacting with alloy
layer and layer. Iron foundries call this special process MC.
Each nodulizer has its own advantages and disadvantages, iron
foundries should base on their products and production process to
choose appropriate nodulizer, in order to decrease the cost of
investment and increase the production efficiency.