1.
Identify the three sources of contraction in a metal casting after pouring. (2’)
The three sources of contraction in a metal are liquid contraction, thermal contraction,
and height reduction from solidification
2.
What are the crystal orientations in the chill zone and columnar zone after metal casting
solidification. (2’)
Chill zone (near the mold wall) randomly oriented equiaxed grains formed by rapid nucleation on
the cold wall.
Columnar zone (inward from chill) elongated grains whose growth axes align with the heat-flow
direction
3.
What is directional solidification? (2’)
Directional solidification is when a a strong thermal gradient is established so the solid–liquid
interface advances in one preferred direction, maintaining a continuous liquid path to prevent
shrinkage. Achieved with chills, insulation
4.
What are some of the general defects encountered in casting processes? Name and briefly
describe them. (2’)
Shrinkage cavity: voids from lack of liquid feed during solidification
Cold shut: streams that fail to fuse or incomplete fill due to premature freezing .
Gas porosity/blows: entrapped gas bubbles
5.
Define bulk density and true density for metallic powders.? (2’)
Bulk density: mass per total bulk volume of a loose powder, including interparticle voids.​
True density: mass per actual solid volume of the particles, excluding all accessible and
closed pores
6.
(SI units) When casting low carbon steel under certain mold conditions, the mold constant in Chvo
30 cm, width = 15 cm, and thickness = 20 mm. (3’)
7.
(SI units) Total solidification times of three casting geometries are to be compared: (1) a sphere wi
cm. The same casting alloy is used in all three cases. (a) Determine the relative solidification times
(c) If the mold constant = 3.5 min/cm in Chvorinov's rule, compute the total solidification time for ea
8.
Determine the shape factors for metal particles of the following ideal shapes: (a) sphere, (b) cubic.