Malleable iron and non malleable iron
How to judge a cast iron is malleable
iron, or it is not malleable iron? Or is there a clear definition
between malleable and non malleable cast iron?
Actually, the answer is very simple, but the judgment will be
Firstly, if client required producing malleable iron, then they will
advise the cast iron grades, such as DIN 1692, ASTM A47, A220, A197,
A338. So, if the cast iron grades are in these standards, then they
will be malleable iron.
Secondly, the production process of malleable cast iron is different
with ductile iron and grey iron castings. Producing malleable iron
needs a key heat treatment process, but most of gray iron and
ductile iron castings will not need heat treatment.
Thirdly, their metallographic is very different, the graphite of
malleable iron is cotton-like, but the ductile iron is ball-like,
and gray iron is flaky.
As for their elongation, malleable iron could reach 2 to 12%, but
gray iron is almost no elongation, ductile iron can reach from 2 to
22%. So, from elongation, you could judge malleable iron with gray
iron, but can not judge it with ductile iron.
Actually, if client choose the malleable iron, most likely, they
prefer some special properties of malleable iron, such as corrosion
resistance, abrasive resistance, good machining capability and shock
However, malleable cast iron can not be forged. Malleable is only
meaning this cast iron has good elongation under stress, but ductile
iron is also meaning this point.
All in all, if client required to produce malleable iron, then you
will have to produce the castings by malleable iron process,
otherwise, it will not be malleable iron. However, if client just
required the tensile strength and elongation, then you should
consider to produce the castings by ductile iron because of lots of
reasons. If you just export them, and need to assure if your casting
parts are belong malleable iron to fill in the HS code, then ductile
iron is also belong to malleable iron range. Only gray iron and cast
steel are not belong to this range.
The followings are some typical casting parts made by
malleable cast iron