A 3-in.-diameter casting was produced. The times required for the so lid-liquid interface to reach different distances beneath the casting surface were measured and are shown in the following table:
Distance from Surface (in.) Time (s)
0.1.........................................32.6
0.3.........................................73.5
0.5.........................................130.6
0.75.......................................225.6
1.0.........................................334.9
Determine
(a) The time at which solidification begins at the surface and
(b) The time at which the entire casting is expected to be solid.
(c) Suppose the center of the casting actually solidified in 720 s. Explain way this time might differ from the time calculated in part (b).