Abstract:
An attempt has been made to produce ductile iron or spheroidal
graphite (S.O) iron and to study it" imporlant properties with a
view to reducing the import of machinery parts made of S.O. iron.
produced miId
an induction
sulphur content
process carried
Locally available (imported) pig iron and locally
steel rods Were u"ed to produce S.O. iron in
furnace. Calcium carbide was used to reduce the
of the charge through a prior desulphurization
out in the department.
The nodule count, the nodularity and the mechanical propertle:;
were found lower in the 8.G. iron produced in the first hent when
the inoculation treatment was carried out in:;ide the ladle along
wilh :;pheroidizalion treatment simultancously and charcoal dust
wa:; used as carburizing material. Bul these Were found better in
the second heat when the spheroidi~ation treatment was carried
out at fir:;t and the inoculalion later and graphite powder was
used a:; earburizing material in"tead of charcoal.
Circular bars having diameter of ~", i", I~, 1t", 2~ and 2t".•ith a
height of J~ each Were cast with the S.O. iron produced in the
firsl heat to ob:;erve the effects of cooling rate on the
morphology of graphite, the nodule count. the nodularity and the
matrix mierostru"lure. The percentage of cementite was found to
increase in the matrix of thinner seelion bars resulting less
number of nodule:;. Pin like iittle :;pheroids were found to
increase in number as the diameter of the bars ioereased. Larger
si7.e and lower nodularity of the :;pheroidal graphite particles
were found in thicker bars. Ferrite ring:; were found In the
microstructure of thicker section bars around the spheroidal
graphite particles.
Specimens cut from these circular bars were annealed at 9500C for
One hour to ob:;erve the effect of the annealing treatment on the
nodule count, the nodularity and lbe matrix microstructure. After
annealing treatment the number of nodules in lhinner section bars
were increased many times and lhe cementile and pearlite matrix
of thinner section baT:; were tran:;formed into fully ferTitic
matrix. But lhe matrix of thicker section bars were partially
lran:;formed into ferrill" matrix.
