چكيده به لاتين
In this study, the role of using the fin in improving the feeding distance in a ductile
iron has been investigated. Riser was a side cylindrical and specimens were plateshaped
with dimensions of 600×120×20mm. The model was molded in two ways with
no fin and with 8 symmetric fins on both sides of its central part in the green sand. The
pouring temperature was 1350℃, and the ductile iron composition was 3.38 %C, 2.21
%Si, 0.04 %Mg and %CE of 4.1%. In order to investigate feeding distance in two
finned and non-finned samples, porosities of the two specimens were evaluated
quantitatively and qualitatively by means of density, radiography and fractography
tests. Also, for a better analysis of the feeding distance, the critical solids fraction and
the modified temperature gradient have been used.
Metallographic results showed that the average diameter of graphite and the nodule
count in the finned sample were 23.55μm and 177 nodules per mm2 and in the nonfinned
sample were 31.31μm and 158 nodules per mm2, respectively. The size and
graphite nodule number in all sections of the sample was almost constant, but the size
and graphite nodule number in the central section of the non-finned sample were
39.06μm and 108 nodules per mm2, respectively. Thermal simulations showed that the
time of stopping the temperature in the Eutectic transformation for all parts of the
finned sample was lower than the non-finned sample in about 100 seconds. Review
the critical solid fraction and modified temperature gradient indicates shrinkage
occurring in the central section of the non-finned sample. Radiographic and fracture
surface images in a non-finned sample showed that in the center of the sample, layer
porosity was formed, but no shrinkage porosity has been observed in the finned
sample. By comparing two samples, it was found that the addition of fins increased
the feeding distance factor from 5.9 to 6.7 . In other words, in this research, the feeding
distance has increased by more than 13%, which could indicate an improvement in the
feeding distance in this alloy.
