Related Questions

Assertion 'a': During casting of aluminium, grain refinement can be achieved by addition of certain alloying elements.
Reason 'r': The addition of the alloying elements may result in the formation of deoxidation products or intermetallic compounds which may act as nucleation sites for grain refinement.
At the mould exit of a continuous caster, the metal consisting of a solidified shell with a liquid metal core exits at the rate of 35 kg S-1. Given that the latent heat of fusion is 3 × 105 J kg-1 and the total rate of heat removal by the mould is 4.2 × 106 W, the mass fraction of solid at the mould exit is . . . . . . . .
Assume that both while solid and liquid remain at the melting point, they are in the mould.
The largest size of immobilised segment of dislocation in a Frank Read (FR) source contained in a polycrystalline material is of the order of grain size. In a metal of 10 μm grain size, the shear stress required to operate such a FR source is 100 MPa. If the grain size in the same metal is reduced to 10 μm, the shear stress required to operate such FR source would be . . . . . . . . MPa.
To reduce the friction between the mould’s surface and casting, a refractory coating is done to the surface of mould.
In permanent mould casting, the mould is pre-heated to its operating temperature before the actual use of mould.
Refractory coating to the metallic mould helps in reducing the chilling effect on the casting.
A 250 mm by 250 mm ingot casting, 1.5 m high and at 1225 K temperature, is stripped from its mold. The casting is made to stand on end on the floor of a large foundry whose wall, floor and roof can be assumed to be at 300 K temperature. Make calculation for the rate of radiant heat interchange between the casting and the room. The casting material has an emissivity of 0.85
The riser is a reservoir of molten metal provided in the casting so that hot metal can flow back into the mould cavity when there is a reduction in the volume of metal due to?
In permanent mould casting, only the metallic type of cores can be used, as the mould material used is also metallic.
The casting processes that require expendable moulds are
P. Investment casting
Q. Low pressure casting
R. Shell moulding
S. Slush casting