# GATE Questions & Answers of Solidification and Cooling

## What is the Weightage of Solidification and Cooling in GATE Exam?

Total 13 Questions have been asked from Solidification and Cooling topic of Casting, Forming and Joining Processes subject in previous GATE papers. Average marks 1.54.

For sand-casting a steel rectangular plate with dimensions 80 mm × 120 mm × 20 mm, a cylindrical riser has to be designed. The height of the riser is equal to its diameter. The total solidification time for the casting is 2 minutes. In Chvorinov’s law for the estimation of the total solidification time, exponent is to be taken as 2. For a solidification time of 3 minutes in the riser, the diameter (in mm) of the riser is __________ (correct to two decimal places).

Equal amounts of a liquid metal at the same temperature are poured into three moulds made of steel, copper and aluminum. The shape of the cavity is a cylinder with 15 mm diameter. The size of the moulds are such that the outside temperature of the moulds do not increase appreciably beyond the atmospheric temperature during solidification. The sequence of solidification in the mould from the fastest to slowest is

(Thermal conductivities of steel, copper and aluminum are 60.5, 401 and 237 W/m-K, respectively. Specific heats of steel, copper and aluminum are 434, 385 and 903 J/kg-K, respectively. Densities of steel, copper and aluminum are 7854, 8933 and 2700 kg/m3, respectively.)

The solidification time of a casting is proportional to ${\left(\frac{V}{A}\right)}^{2}$ ,Where V is the volume of the casting and A is the total casting surface area losing heat. Two cubes of same material and size are cast using sand casting process. The top face of one of the cubes is completely insulated. The ratio of the solidification time for the cube with top face insulated to that of the other cube is

A cube and a sphere made of cast iron (each volume 1000 cm3) were cast under identical conditions. The time taken for solidifying the cube was 4 s. The solidification time ( in s) for the sphere is ________.

Ratio of solidification time of a cylindrical casting (height=radius) to that of a cubic casting of side two times the height of cylindrical casting is________

Match the casting defects (Group A) with the probable causes (Group B):

 Group A Group B P: Hot tears 1: Improper fusion of two streams of liquid metal Q: Shrinkage 2: Low permeability of the sand mould R: Blow holes 3: Volumetric contraction both in liquid and solid stage S: Cold Shut 4: Differential cooling rate

The hot tearing in a metal casting is due to

A cylindrical riser of 6 cm diameter and 6 cm height has to be designed for a sand casting mould for producing a steel rectangular plate casting of 7 cm × 10 cm × 2 cm dimensions having the total solidification time of 1.36 minute. The total solidification time (in minute) of the riser is _______

A cube shaped casting solidifies in 5 min. The solidification time in min for a cube of the same material, which is 8 times heavier than the original casting, will be

A cubic casting of 50 mm side undergoes volumetric solidification shrinkage and volumetric solid contraction of 4% and 6% respectively. No riser is used. Assume uniform cooling in all directions. The side of the cube after solidification and contraction is

Two streams of liquid metal which are not hot enough to fuse properly result into a casting defect known as