reaching 700-705°C at the end of blowing. After the
inoculant addition was completed, the melt was held
for 510 min to increase the temperature to about
730°C. The melt was then cast into chill moulds.
The inoculant containing ingots were remelted to
study the effect of holding time and alloying addition
on the behaviour of the particles. In order to test the
stability of the particles in the melt, the bath was held
for different periods (30 min-6 h) at 750°C without
any Ti addition. After remelting, a slow agitation
( - 70-80 rpm) was maintained to keep the particles
suspended in the melt. For studying the effect of
solute Ti, the temperature of the bath was maintained
at 750°C or more depending on the level of Ti
addition. Ti additions were done through AI-Ti
master alloy, the composition of which is given in
Table 1. In the case of the 2% Ti addition the bath
temperature was raised to 900°C the addition was
made, and the melt was cast at 900’C. For other
levels of Ti additions, the temperature on addition
was 75O’C and the melt was cast at 730°C. Holding
times after remelting were generally very short (of the
order of 20-30 min).
To study the effect of cooling rate, a step mould
was used with different preheat temperatures which
varied from room temperature to 400°C. Cooling
curves for 356 alloys were obtained from each step at
each preheat temperature. The cooling rates were
estimated from the curves, as the average slope
between the liquidus and eutectic temperature.
Although there will be a slight difference due to the
different latent heat of fusion, the cooling rates
obtained from the 356 alloys are considered to be the
same in the case of the other alloys. A combination
of metallographic (optical and SEM) and micro-analytical
(EPMA) techniques was employed to study the
behaviour of the inoculants in the solidified samples.