| Summary: | 碩士 === 國立中央大學 === 機械工程學系 === 85 === The effect of alloying elements on the ferrite fraction of
ductile iron,after ferritizing treatment,had been fully
investigated in this study.heat treatment conditions included
austitization at 900 and 930C for 1.5and 2 hours;ferritizing
treatment at 700 and 730C for 1~3 hours. Experimental results
showed that:(1).base ductile iron without addition of Cu or Ni
developed a fully ferritematrix in a short ferritizing time but
with a low hardness in the matrix.(2).Ductile iron added with
0.2% Cu showed a slightly longer ferritizing time to developed a
giving fraction of ferrite comparing with base iron
withoutaddition of Cu.(3).Ductile iron illustrated a fully
ferrite matrix after ferritization treatment.The ferritizing
time exceeding three hours was necessary,ifthe ductile iron
added with 0.65% Cu or 0.5%-0.48%Ni.(4).According to the results
of the regression analyses,nodule counts,alloyelements and
carbon equivalent greatly affected the ferrite fraction
inductile irons after ferritization treatment.The regression
models were purposed to correlate the effect of
alloyingelements,nodule counts and nodular diameter on the
ferrite fraction developed for a giving ferritizing time.
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