MCQ’s On Cooling and Solidification
Q. Which of the following characteristics is mainly considered for the solidification of castings?
A. Appearance
B. Crystal structure
C. Moulding capacity
D. Surface finish
.
Answer: B
Q. A proper care should be taken while cooling or solidification of castings to avoid defect formation.
A. True
B. False
.
Answer: A
Q. In the case of pure metals, liquid metal should be cooled above their freezing points.
A. True
B. False
.
Answer: B
Q. Which of the following types of crystal are formed near the mould face during solidification?
A. Big crystals with random orientation
B. Small crystals with systematic orientation
C. Small crystals with random orientation
D. Big crystals with systematic orientation
.
Answer: C
Q. As the solidification progresses gradually inwards, small crystals with systematic orientation are formed.
A. True
B. False
.
Answer: B
Q. An alloy, unlike a pure metal, does not have a sharply defined freezing temperature.
A. True
B. False
.
Answer: A
Q. Which of the following factors is independent to the direction of crystal growth in an alloy?
A. Thermal gradient
B. Composition gradient
C. Variation of solidus temperature
D. Material aesthetics
.
Answer: D
Q. The difference in the progress of crystallization at different points in the casting material causes fast and abrupt growth of crystals.
A. True
B. False
.
Answer: B
Q. A dendritic crystal growth structure is formed by the difference in progress of crystallization at different points in the casting material.
A. True
B. False
.
Answer: A
Q. The presence of solid crystals at solid-liquid interface makes feeding of molten metal more easily.
A. True
B. False
.
Answer: B
Q. Which of the following parts can be used to have uniform crystallization at all over the points in the casting material?
A. Chaplets
B. Biscuit
C. Chills
D. Core
.
Answer: C
Q. Rapid heat extraction from the casting causes narrowing of liquid-solid zone which sweeps itself across the molten metal.
A. True
B. False
.
Answer: A
Q. Which of the following is mostly analyzes during the casting and solidification of casting material?
A. Mould coating
B. Mould material
C. Mould aesthetics
D. Heat transfer
.
Answer: D
Q. The solidification time can be increased by increasing the thickness of the mould.
A. True
B. False
.
Answer: A
Q. A large shape of a riser is mainly used for the casting of grey cast iron.
A. True
B. False
.
Answer: B
Q. Feeding of an alloy in the mould is considered to be difficult if centre-line feeding resistance (CFR) is_____
A. greater than 70%
B. less than 70%
C. less than 20%
D. 0%
.
Answer: A
Q. Which of the following is independent of the solidification time of the casting?
A. Mould material
B. Chaplets
C. Heat transfer coefficient
D. Mould wall temperature
.
Answer: B
Q. Casting which is cooled quickly generally have coarse grain structure.
A. True
B. False
.
Answer: B
Q. Refractory coating to the metallic mould helps in reducing the chilling effect on the casting.
A. True
B. False
.
Answer: A
Q. The scale of segregation cannot be reduced or avoided by implementing any kind of method.
A. True
B. False
.
Answer: B
Q. The transfer of heat across a gap (an interface between mould and casting) is given by_____
A. q = h+∆T
B. q = h/∆T
C. q = h*∆T
D. q = h-∆T
.
Answer: C
Q. What should be the value of biot number (Bi) for chill mould castings?
A. Less than 1
B. Greater than 1
C. Greater than 5
D. Greater than 11
.
Answer: A
Q. The deduction of cooling rate from a simple heat balance can only be possible when the process is isothermal and the specific heats of the liquid and the solid are same.
A. True
B. False
.
Answer: A
Q. Increase in mould thickness always decreases the rate of solidification of casting material.
A. True
B. False
.
Answer: B
Q.During the solidification of casting in an insulating mould, the heat transfer takes place from the upside of the moulding system which might cause defects in the castings.
A. True
B. False
.
Answer: B
Q.Concave, convex and plane types of metal mould interfaces are mainly considered for the estimation of freezing time of metal.
A. True
B. False
.
Answer: A
Q.In solidification of large casting in an insulating mould, precise calculations are made for the analysis of freezing time of the complex contours of casting.
A. True
B. False
.
Answer: B
Q. Which of the following metal-mould interfaces show the divergent nature of heat flow from the casting material?
A. Concave
B. Square plane
C. Rectangular plane
D. Convex
.
Answer: D
Q.More divergence of heat flow from the interface shows consequently high solidification rate of the casting.
A. True
B. False
.
Answer: A
Q. The amount of heat removed from the castings is dependent on the amount of superheating in the casting.
A. True
B. False
.
Answer: A
Q.Which of the following formulas is given by Chvorinov’s rule for the estimation of total solidification time (ts)?
A. ts = B/(V/A.n
B. ts = B*(A/V)n
C. ts = B*(V/A.n
D. ts = B/(A/V)n
.
Answer: C
Q. Chvorinov’s rule is commonly used for prediction of surface finish of the casting made in the mould.
A. True
B. False
.
Answer: B
Q.It is very necessary to use high refractoriness of mould material for the making of insulated mould.
A. True
B. False
.
Answer: A
Q.The solidification of casting in an insulating mould produces casting of hard and brittle nature.
A. True
B. False
.
Answer: B
Q. During the solidification of casting in an insulating mould, the heat transfer takes place from the upside of the moulding system which might cause defects in the castings.
A. True
B. False
.
Answer: B
Q. Concave, convex and plane types of metal mould interfaces are mainly considered for the estimation of freezing time of metal.
A. True
B. False
.
Answer: A
Q.In solidification of large casting in an insulating mould, precise calculations are made for the analysis of freezing time of the complex contours of casting.
A. True
B. False
.
Answer: B
Q. Which of the following metal-mould interfaces show the divergent nature of heat flow from the casting material?
A. Concave
B. Square plane
C. Rectangular plane
D. Convex
.
Answer: D
Q.More divergence of heat flow from the interface shows consequently high solidification rate of the casting.
A. True
B. False
.
Answer: A
Q. The amount of heat removed from the castings is dependent on the amount of superheating in the casting.
A. True
B. False
.
Answer: A
Q.Which of the following formulas is given by Chvorinov’s rule for the estimation of total solidification time (ts)?
A. ts = B/(V/A.n
B. ts = B*(A/V)n
C. ts = B*(V/A.n
D. ts = B/(A/V)n
.
Answer: C
Q. Chvorinov’s rule is commonly used for prediction of surface finish of the casting made in the mould.
A. True
B. False
.
Answer: B
Q. It is very necessary to use high refractoriness of mould material for the making of insulated mould.
A. True
B. False
.
Answer: A
Q. The solidification of casting in an insulating mould produces casting of hard and brittle nature.
A. True
B. False
.
Answer: B
Q. During the solidification of casting in an insulating mould, the heat transfer takes place from the upside of the moulding system which might cause defects in the castings.
A. True
B. False
.
Answer: B
Q. Concave, convex and plane types of metal mould interfaces are mainly considered for the estimation of freezing time of metal.
A. True
B. False
.
Answer: A
Q. In solidification of large casting in an insulating mould, precise calculations are made for the analysis of freezing time of the complex contours of casting.
A. True
B. False
.
Answer: B
Q. Which of the following metal-mould interfaces show the divergent nature of heat flow from the casting material?
A. Concave
B. Square plane
C. Rectangular plane
D. Convex
.
Answer: D
Q. More divergence of heat flow from the interface shows consequently high solidification rate of the casting.
A. True
B. False
.
Answer: A
Q. The amount of heat removed from the castings is dependent on the amount of superheating in the casting.
A. True
B. False
.
Answer: A
Q. Which of the following formulas is given by Chvorinov’s rule for the estimation of total solidification time (ts)?
A. ts = B/(V/A.n
B. ts = B*(A/V)n
C. ts = B*(V/A.n
D. ts = B/(A/V)n
.
Answer: C
Q. Chvorinov’s rule is commonly used for prediction of surface finish of the casting made in the mould.
A. True
B. False
.
Answer: B
Q. It is very necessary to use high refractoriness of mould material for the making of insulated mould.
A. True
B. False
.
Answer: A
Q. The solidification of casting in an insulating mould produces casting of hard and brittle nature.
A. True
B. False
.
Answer: B
Q. Which of the following is used for the controlling of heat flow in the casting process?
A. Mechanical resistance
B. Biscuit
C. Chaplets
D. Thermal resistance
.
Answer: D
Q. Perfect wetting only occurs when there is no contact resistance phenomenon in the casting interface.
A. True
B. False
.
Answer: A
Q. Superheating is the only main consideration for the existence of no contact resistance between the metal and mould.
A. True
B. False
.
Answer: B
Q. Good thermal conductivity of the solidified metal can lower down the surface temperature below than the freezing temperature.
A. True
B. False
.
Answer: A
Q. Surface irregularities of the solidifying casting can increase the temperature at the interface.
A. True
B. False
.
Answer: B
Q. The heat transfer through the interface of metal and mould is always considered as of convection mode.
A. True
B. False
.
Answer: B
Q. Conduction mode of heat transfer mainly depends upon the conductivity of the medium and the size of a gap at the interface.
A. True
B. False
.
Answer: A
Q. A gap of finite thickness at the interface of mould and metal always increases the heat flux.
A. True
B. False
.
Answer: B
Q. For the complex geometries of the casting, the calculation is more difficult to obtain the air gap at the interface.
A. True
B. False
.
Answer: A
Q. The magnitude of the air gap at the interface of casting and mould continuously decreases with time.
A. True
B. False
.
Answer: B
Q. A thin water cooled mould always tends to make a casting of soft and ductile nature.
A. True
B. False
.
Answer: B
Q. Rapid cooling of strand surfaces of casting is mainly done to increase casting speed and productivity.
A. True
B. False
.
Answer: A
Q. In the continuous casting line, the solidification or cooling rate is normally very high.
A. True
B. False
.
Answer: A
Q. The analysis of heat flow is much easy in chilled casting process compared to the other type of castings.
A. True
B. False
.
Answer: B
Q. The surface temperature of chilled casting is normally lower than the melting point of the metal.
A. True
B. False
.
Answer: A
Q. In any condition, the effects of superheat cannot be considered in the process of chilled castings.
A. True
B. False
.
Answer: B
Q. During solidification of casting material, the successive droplets of the material take a longer time to solidify than the first droplet.
A. True
B. False
.
Answer: A
Q. Which of the following temperature ranges (in Kelvin) can start the re-melting of droplets of casting material?
A. 400 – 450
B. 450 – 500
C. 500 – 600
D. 600 – 700
.
Answer: D
Q. Thermal contact resistance can be affected by impact or thermal parameters during the casting process.
A. True
B. False
.
Answer: B
Q. During solidification, the interface temperature is independent to the magnitude of contact resistance.
A. True
B. False
.
Answer: A
Q. In continuous casting technology, solidification of casting starts in a thick sand mould of a closed structure.
A. True
B. False
.
Answer: B
Q. Handling of very high heat flux can be possible in continuous casting technology.
A. True
B. False
.
Answer: A
Q. Predominant resistance in mould of casting system generally produces castings of brittle nature.
A. True
B. False
.
Answer: B
Q. In the continuous casting process, there is a strong possibility of breaking of casting parts at the initial stage of solidification.
A. True
B. False
.
Answer: B
Q. . Minimization of friction between the mould and casting surface can reduce the chances of tearing of thin parts of the casting.
A. True
B. False
.
Answer: A
Q. To reduce the friction between the mould’s surface and casting, a refractory coating is done to the surface of mould.
A. True
B. False
.
Answer: B
Q. Lubrication at the interface is arises due to the infiltration of mould slag into the gap between the mould and casting.
A. True
B. False
.
Answer: A
Q. Which of the following formulas is used for the determination of solid friction (fs) between the mould and casting during solidification?
A. fs = ηs-H
B. fs = ηs/H
C. fs = ηs+H
D. fs = ηs*H
.
Answer: D
Q. Due to mould oscillation to minimize friction, oscillation marks formed on the surface of casting does not affect the castings.
A. True
B. False
.
Answer: B
Q. Analysis of frictional concept at the interface is very important and necessary for the increase in casting speed.
A. True
B. False
.
Answer: A
Q. Residual stresses are also known as locked-in stresses.
A. True
B. False
.
Answer: A
Q. Manufacturing process is the only consideration which can cause residual stresses in the casting.
A. True
B. False
.
Answer: B
Q. Localized yielding of material can also be the reason for the generation of residual stresses in the casting.
A. True
B. False
.
Answer: A
Q. Residual stresses can cause any defects in the casting except distortion of the casting component.
A. True
B. False
.
Answer: B
Q. Residual stresses can also be calculated the same way as the stresses due to the external loads is calculated.
A. True
B. False
.
Answer: B
Q. The presence of residual stresses in a component can prevent failure of the casting component.
A. True
B. False
.
Answer: A
Q. By using resin bonded sand in the making of mould, the stresses produced in the casting can be reduced.
A. True
B. False
.
Answer: A
Q. Natural aging treatment is a fast and accurate method for reducing residual stresses in the casting compared to the heat treatment.
A. True
B. False
.
Answer: B
Q. Machinability of the casting product can be improved by reducing the residual stresses in the casting.
A. True
B. False
.
Answer: A
Q. Cold cracking failure of the casting product can be avoided by shot peening method which induces internal stresses in the casting.
A. True
B. False
.
Answer: B
