(a) and Ti = 1280o C (2336F).
(b)
Figure 9. (a) Eutectic cell density, N as a function undercooling, ∆Tm and (b) casting modulus, M C s1/2
for inoculated and base iron. Continuous lines are predicted results based on Eqns. (8) and (11), and Tables 1 and 2, for a = 0.11 J/cm2 o
(a) (12) and data from Tables 1 and 2 for a = 0.11 J/(cm2 o %C and 2.55 %Si. (Experimental point for ductile iron from Reference 37) , Ti = 1270o
• Type of spheroidizing agent and of the inoculation treatment—Table 2 shows the nucleation coeffi- cients for two different ductile iron melt treatments (Melts 1 and 2). Notice from Fig. 11, that the ex- perimental results are in good agreement with the
predicted nodule or cell counts as a function of ∆Tm or M (Eqns. 8 and 12).
•
Spheroidization and inoculation treatment temper- ature—the influence of the Mg treatment tempera- ture or of the inoculation temperature on the ex-
International Journal of Metalcasting/Summer 10 •
hibited nucleation coefficients is not known. How- ever, from the work of Merchant, 28
it is found that
a high temperature of bath superheating for a base iron destined for inoculation combined with a low inoculation temperature promotes a high graphite nodule count. A similar conclusion is valid for cast iron with flake graphite.38
Fading of inoculation—a characteristic feature of the inoculation process in cast iron is its fading ef- fect. Over time the substrates for active graphite
43
(b)
Figure 10. (a) The influence of added silicon from inoculant on cell and (b) the influence of the amount of inoculant, mi
on nodule count. Continuous lines are predicted results based on Eqn. C s1/2
C (2318F) in a melt with 3.66
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