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pherodizing of molten Cast Iron from riser cavity during mould filling

In this investigation a new procedure has been developedfor producing ofCast Iron parts. The Cast Iron parts were produced as two layers during of solidification. They had two zones, outer zone which was Grey Iron and inner zone which was Ductile Iron. At first, a complex cast part with a blind riser was designed. Second, some inoculants were placed into the blind riser on a wire screen for inoculation ofmelt. Finally, the micro structure from the outer skin toward the inner zone ofthe part was investigated by metallographic testing. Results showed that graphiteʹs in outer layers were from type of flack graphite, and the central zones were spherical graphite. In fact, at the first step of solidification, outer skin is solidified as Grey Iron. Then due to contact melt and inoculants material concurrent with cavity shrinkage as well as back pressure into the riser, a flow of inoculated melt move from the riser toward mold cavity. This phenomenon lead to formation ofspherical graphiteʹs at the central zones. This procedure is very economic for casting industries, because in this technique the blind riser has the role of a reaction cavity, instead ofmelt compensation.