S.G. Iron Castings
SG iron is called as spheroidal graphite
cast iron, or also called as ductile
iron or nodular iron.
This iron material is very common in China and worldwide, because of
its superior physical properties and mature production processes.
SG iron is suitable for producing many types of castings, such as
the iron parts for agricultural and engineering machinery, pump and
valve bodies, pipe fittings, manhole covers etc. The sg iron is
about taken 70% production output for all
iron castings worldwide.
High tensile strength and good ductility are the main characters of
s.g. cast iron. As for sg iron 900, its tensile strength can exceed
827 Mpa, yield strength can exceed 621 Mpa. As for sg iron 400, its
elongation can exceed 18%. The most common material grades are sg
iron 400, 450 and 500 because of their excellent comprehensive
The hardness range of sg iron castings is as following:
400/18, 400-15: BHN 130-180
450/10: BHN 160-210
500/7: BHN 170-230
600/3: BHN 190-270
700/2: BHN 225-305
800/2: BHN 245-335
900/2: BHN 280-360
The chemical composition has the following range:
C: 2.7-3.8%, Si: 0.5-3.8%, Mn: 0.2-0.7%, S ≤0.02, P ≤0.1, Cr ≤0.15.
The above chemical composition is just from foundry experience,
which can not be taken as the quality standard of inspecting sg iron
As for sg iron pipe, it could be produced by continuous casting
process. But as for the most of sg iron castings,
sand casting process
is most suitable production method. Green sand, resin sand and shell
molding are the common molding process in China.