Production of ductile iron and study of its important properties

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.