MCQ’s on Foundry Introduction & Materials
Q. Which of the following is not a type of a foundry?
A. Captive foundry
B. Jobbing foundry
C. Semi Production foundry
D. Auto production foundry
.
.Answer: D
Explanation: Foundries are classified according to their type of work and the form of constitution and structure of their organization. The foundries are hence classified into four types namely, captive foundry, jobbing foundry, semi production foundry and production foundry.
Q. What is the total capacity possessed by ferrous Indian foundries?
A. 1,00,000 tons
B. 1,50,000 tons
C. 2,00,000 tons
D. 2,50,000 tons
.
.Answer: D
Explanation: There are many foundries in India. A few big foundries are located in Durgapur, Asansol, Rourkela, Bhopal and Bangalore. The total capacity possessed by Indian ferrous foundries is more than 2,50,000 tons.
Q. Which of the following is a ferrous foundry?
A. Brass foundry
B. Bronze foundry
C. High alloy steel foundry
D. Zinc-base foundry
.
..Answer: C
Explanation: Among the following, a high alloy steel foundry is a type of steel foundry and steel foundries come under ferrous foundries, while the remaining ones are non-ferrous foundries.
Q. Which of the following is not a metal joining process?
A. Riveting
B. Bending
C. Pressing
D. Brazing
.
.Answer: B
Explanation: Riveting, brazing, pressing, soldering, adhesive bonding and bolt-screw fastening are few of the techniques of metal joining process. But, bending is not one of them, it is a shaping process.
Q. In an automobile engine, up to what percent of parts are manufactured by casting?
A. 65%
B. 75%
C. 80%
D. 90%
.
.Answer: D
Explanation: Casting is one of the most all round process used in manufacturing. Up to 90% of the automobile engine parts are manufactured using casting, and around 50% of the total weight of the tractor is manufactured using casting.
6. Which of the following is not a metal removing process?
A. Grinding
B. Milling
C. Swaging
D. Hobbing
.
..Answer: C
Explanation: Grinding, milling, hobbing, planning, reaming, shaping, boring, turning and broaching are a few of the techniques of metal removing process. But, swaging is not a part of them, it is a type of metal shaping process.
Q. Which of the following is a metal shaping process?
A. Press forging
B. Broaching
C. Riveting
D. Lapping
.
Answer: A
Explanation: Among the following, broaching is a metal machining process or a metal removal process, riveting is a metal joining process, lapping is a surface finishing process and press forging is a shaping process.
Q. Casting provides uniform directional properties.
A. True
B. False
.
Answer: A
Explanation: Casting provides a great amount of freedom in terms of design. It helps in providing uniform directional properties and good vibrational properties.
Q. Which of the following is not a surface finishing process?
A. Honing
B. Grinding
C. Boring
D. Lapping
.
..Answer: C
Explanation: Honing, grinding, anodizing, lapping, polishing and metal spraying are a few of the surface finishing techniques. But, boring is not one of them, it is a technique that is used for metal removal process.
Q. Products made through casting can avoid joining process.
A. True
B. False
.
Answer: A
Explanation: Products which are made from casting processes, possess an advantage of being formed into one single piece. When the production is done in one piece, it eliminates the requirement of any joining process.
Q. Which of the following is not a cast steel?
A. Low alloy steel
B. Magnesium alloy steel
C. Carbon steel
D. High alloy steel
.
.Answer: B
Explanation: Cast steel are a further classification of foundry metals and alloys under ferrous metals and alloys, that is, having iron base. Low alloy steel, high alloy steel and carbon steel are cast steels, but not magnesium alloy.
Q. Which of the following forms of iron is least malleable?
A. Austenitic
B. Pearlitic
C. Ferritic
D. Martensitic
.
Answer: A
Explanation: Malleable irons are cast irons which are classified under iron base materials, under foundry metals and alloys. Among these phases of iron, the austenite phase of iron is measured to be showing the least amount of malleability.
Q. Which among the following is not a cast iron?
A. White iron
B. Compacted graphite iron
C. Gray cast iron
D. Pig iron
.
.Answer: D
Explanation: Among the following, white iron, compacted cast iron and gray cast iron are different types of cast irons, but pig iron is not. It is from pig iron, that cast irons are made, by re-melting them.
Q. What is the amount of carbon present in low carbon steel?
A. Less than 0.5%
B. Less than 0.7%
C. Less than 0.4%
D. Less than 0.2%
.
.Answer: D
Explanation: Low carbon steel has the lowest amount of carbon mixed with iron in the alloy. The amount of carbon present in low carbon steel is less than 0.2% and that of medium carbon steel has carbon composition of about 0.2% to 0.5%.
Q. What is the amount of carbon present in high carbon steel?
A. More than 0.5%
B. More than 0.7%
C. More than 0.4%
D. More than 0.2%
.
Answer: A
Explanation: More than 0.5% amount of carbon present in high carbon steel.
6. Which among the following is a heavy metal?
A. Titanium base
B. Aluminium base
C. Zinc base
D. Magnesium base
.
..Answer: C
Explanation: The given metal bases are all non-ferrous metal bases, which are classified under foundry metals and alloys. Among these, the only heavy metal is the zinc base, while all others are light metals.
Q. Which of the following is a light metal?
A. Copper base
B. Lead base
C. Nickel base
D. Magnesium base
.
.Answer: D
Explanation: Magnesium base is a light metal.
Q. What is the amount of silicon present in cast carbon steels?
A. 0.25% – 0.6%
B. 0.25% – 0.8%
C. 0.45% – 0.9%
D. 0.45% – 0.1%
.
.Answer: B
Explanation: The amount of silicon that is present in terms of percentage composition is found to be 0.25% to 0.8%. Elements like silicon and manganese are added in the steel alloys for the purpose of deoxidation.
Q. What is the amount of manganese present in cast carbon steels?
A. 0.5% – Q.0%
B. 0.25% – 0.5%
C. 0.45% – 0.8%
D. 1% – 2%
.
Answer: A
Explanation: 0.5% – Q.0% amount of manganese present in cast carbon steels.
Q. Chromium is added to stainless steel.
A. True
B. False
.
Answer: A
Explanation: Stainless steels are of three types, martensitic, ferritic and austenitic. Stainless steels are resistive to corrosion. These stainless steels contain chromium or nickel apart from its regular additives.
Q. Presence of which material in a gray cast iron causes reduced ductility?
A. Graphite
B. Aluminium
C. Coke
D. Zinc
.
Answer: A
Explanation: Among all the types of cast irons that are manufactured, gray cast irons are most widely used. The colour of this alloy is dull gray. Gray cast iron contains graphite flakes, which are responsible for the reduced ductility and strength.
Q. What would be the tensile strength of gray cast iron of class 20?
A. 120 MPa
B. 163 MPa
C. 138 MPa
D. 152 MPa
.
..Answer: C
Explanation: Tensile strength of gray cast iron of class 20 is 163 MPa.
Q. What is the tensile strength of thick gray cast iron?
A. 71 MPa
B. 83 MPa
C. 95 MPa
D. 107 MPa
.
.Answer: B
Explanation: Tensile strength of thick gray cast iron is 83 MPa.
Q. What is the tensile strength of thick gray cast iron?
A. 276 MPa
B. 283 MPa
C. 295 MPa
D. 207 MPa
.
Answer: A
Explanation: Tensile strength of thick gray cast iron is 276 MPa.
Q. Up to what mass of gray cast irons can shell molds take?
A. 300 kg
B. 400 kg
C. 500 kg
D. 600 kg
.
..Answer: C
Explanation: Shell molding is one of the most important processes which has also been employed for the production of gray cast irons. Gray cast irons weighing up to around 500 kg are usually processed by this method.
6. Green sand molding provides the best surface finish.
A. True
B. False
.
.Answer: B
Explanation: Green sand moldings are found to provide good amount of surface finish, but an even better quality of surface finish and accuracy of dimensions is offered by shell molding process.
Q. Shell molding process is a costly process for gray iron castings.
A. True
B. False
.
.Answer: B
Explanation: When gray cast irons have to be processed, there is some amount of machining required to it, which demand high costs. But, if gray cast irons have to be shell molded, the overall cost of the product goes down, making it an economical process.
Q. Up to what thickness can hot box process can be used for production?
A. 10 mm- 40 mm
B. 30 mm- 50 mm
C. 40 mm- 80 mm
D. 70 mm- 100 mm
.
.Answer: D
Explanation: In hot box process, there is a core box employed, wherein the sand mixtures are poured along with the liquid resins, which act as binders. The thickness up to which hot box process can be used is 70 mm to 100 mm.
Q. Which of the following materials cannot be used for making a core box?
A. Aluminium
B. Steel
C. Zinc
D. Cast iron
.
..Answer: C
Explanation: None.
Q. What is the temperature in a core box typically?
A. 120°C – 160°C
B. 180°C – 260°C
C. 200°C – 270°C
D. 290°C – 350°C
.
.Answer: B
Explanation: None.
Q. What should be the range of percentage of carbon (C. in iron (Fe) to be called as cast iron?
A. 0.1-0.5
B. 0.5-Q.0
C. Q.0-Q.0
D. Q.0-Q.0
.
.Answer: D
Explanation: Cast iron is the oldest ferrous material that is used for commercial purposes. It is mainly a mixture of iron (Fe) and carbon (C.. It can also include materials like sulfur (S), silicon (Si), and manganese (Mn). Generally, for the cast iron, the percentage of carbon in iron is 2 to 5 percent.
Q. The shaking out of cast iron casting from mould cavity is known as fettling process.
A. True
B. False
.
.Answer: B
Explanation: The cast iron is first melted in furnace and then poured into the mould cavity. After cooling of cast iron in the mould it is broken out. All the excess of metal from the process, gates, runners etc are removed in a process called as fettling, which also have operations like grinding and shot blasting to produce the good surface finish of the castings.
Q. Cast iron generally has low tensile strength but excellent compressive strength.
A. True
B. False
.
Answer: A
Explanation: Cast iron is normally of nonmalleable and brittle nature which defines that, it is not easy to bend or stretched the casting into any shape due to low tensile strength. Cast iron parts tend to fracture by little of deformation, but cast iron has excellent compressive strength which highly required in making of structures of buildings and bridges.
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Q. Which of the following types of iron represents purest form of iron in the manufacturing process?
A. Pig iron
B. White cast iron
C. Wrought iron
D. Grey cast iron
.
..Answer: C
Explanation: The purest form of iron is wrought iron which has negligible amount of carbon in it. It is highly malleable and tough material which can be used for making products by rolling or forging operation instead of casting process. It is basically obtained by melting pig iron which is also called crude iron.
Q. Which of the following types of cast iron includes black flakes of graphite in it?
A. White cast iron
B. Grey cast iron
C. Ductile cast iron
D. Malleable cast iron
.
.Answer: B
Explanation: Grey cast iron generally includes thin and little black flakes of graphite. These black flakes cause cast iron to appear in grey color, so it is called as grey cast iron. Presence of graphite can make it use as a lubricant in some manufacturing processes. But it has less tensile strength and toughness than the other cast irons.
Q. The cast irons are highly corrosive resistant material due to presence of high silicon content in it.
A. True
B. False
.
Answer: A
Explanation: The composition of cast iron generally varies depending on the grade of pig iron used in its manufacturing process. High silicon content in cast iron makes it resistance to oxidation and corrosion by creating a tight adhering oxide layer to minimize other further attacks. Iron castings are used in applications where this type of resistance gives relatively good service.
Q. High manganese content in cast iron provides excellent weld-ability of the material.
A. True
B. False
.
.Answer: B
Explanation: Cast iron mostly contains 2 to 5% carbon, 1 to 3% silicon and approx 1% manganese. The presence of such contents makes their weld-ability poor. Cast irons are relatively cheap and can be easily casted into any complex shapes and machined, but most of the grades of cast iron are not weld-able.
Q. Cast iron is widely used in industries because of its high ratio of performance to cost involved in manufacturing.
A. True
B. False
.
Answer: A
Explanation: Cast iron is widely used because of its high ratio of performance to the cost that they offer. This high value of ratio is also achieved by easy controlling of microstructure and properties in the casting condition, this enables its various applications without giving any heat treatment to the casted parts or components.
Q. Grey cast iron generally has poor machinability due to the presence of graphite flakes in it.
A. True
B. False
.
.Answer: B
Explanation: When the fracture of grey cast iron occurs, the crack path follows the graphite flakes and the fracture surface appears grey in color due to the presence of graphite. The graphite flakes have good damping features and high machinability because the graphite flakes work as a chip breaker and also lubricates the tools or machines.
Q. Which of the following parts are mostly manufactured by using grey cast iron?
A. Pistons
B. Surgical equipment’s
C. Thin sheets
D. Engine blocks
.
.Answer: D
Explanation: The fluidity and expandability of molten grey cast iron at the time of solidification, due to the formation of graphite flakes, this iron becomes ideal for the manufacturing of shrinkage free and intricate castings components like engine blocks. The graphite presence greatly enhances mechanical properties in grey cast iron.
Q. Presence of which material in aluminium alloy provides ductility to the alloy?
A. Silicon
B. Iron
C. Copper
D. Zinc
.
..Answer: C
Explanation: With the presence of about 2% to 5% of copper metal in aluminium alloy aids in the increase in ductility of the alloy, that is, it becomes easy for the alloy to be stretched into wires.
Q. Which furnace is not used for heating aluminium alloys?
A. Electric arc furnace
B. Pot furnace
C. Induction heating furnace
D. Crucible furnace
.
Answer: A
Explanation: Aluminium alloys can be melted or heated directly or indirectly by fuel firing furnace. The heating can take place in a pot furnace, induction heating furnace, a crucible furnace or a reverberatory furnace.
Q. Which of the following is not a purpose of fluxing and flushing the aluminium alloys?
A. Removal of dissolved hydrogen
B. Removal of dissolved oxygen
C. Separation of dross from melt
D. Entrapment of dross
.
.Answer: B
Explanation: Fluxing and flushing are an important task in aluminium alloy foundries. It is done for removing the dissolved hydrogen from the melt, for separating the dross from molten metal and to entrap the dross.
Q. What is the silicon composition present in an LM-17 cast aluminium alloy?
A. 3%
B. 12%
C. Q.5%
D. 1Q.5%
.
.Answer: D
Explanation: In an LM-1 cast aluminium alloy, silicon content is 3%. In an LM-13 cast aluminium alloy, silicon content is 12%. In an LM-8 cast aluminium alloy, silicon content is Q.5% and in an LM-17 cast aluminium alloy, the silicon content is 1Q.5%.
Q. Which gas is not used for fluxing and flushing in aluminium alloys?
A. Argon
B. Chlorine
C. Nitrogen
D. Oxygen
.
.Answer: D
Explanation: Fluxing and flushing is an operation which is done for the removal of hydrogen from the molten metal. In this process, argon gas, chlorine gas, nitrogen gas and helium gas are used as fluxes and not oxygen.
6. Up to what length can the surface finish be achieved by green sand in aluminium alloys?
A. 600 micro inch
B. 650 micro inch
C. 700 micro inch
D. 750 micro inch
.
.Answer: B
Explanation: When green sand is used for molding in aluminium alloys, the surface finish can be achieved from about 300 micro inch to 650 micro inch, which is about 7500 micro mm to 16,250 micro mm.
Q. Which of the given metals is not counted among late additions in aluminium alloys?
A. Boron
B. Titanium
C. Manganese
D. Sodium
.
..Answer: C
Explanation: There are certain metals which are added very late in the molten cast. By doing this, aluminium alloys get refined. A few of those metals are, boron, titanium, sodium, chromium and columbium. Manganese is added in aluminium during the operation, not late.
Q. Aluminium alloys are not susceptible to which of the following?
A. Macro shrinkage
B. Drossing
C. Micro shrinkage
D. Solidification shrinkage
.
Answer: A
Explanation: Aluminium alloys are susceptible to drossing, micro shrinkages and solidification shrinkages, but not to macro shrinkages. For the prevention of entering of dross in mold cavity, gating system is installed.
Q. A runner is located away from the drag.
A. True
B. False
.
.Answer: B
Explanation: A runner has to be located in the drag. The area of the runner should be small and ideally equal to the ingate area. It should be streamlined to avoid turbulence.
Q. Pouring basins are used for reducing vortex formation.
A. True
B. False
.
Answer: A
Explanation: The design made for pouring basins in the working of aluminium alloys, is purposed for the reduction of turbulence and vortex formation. It also aids in the reduction of mechanical washing of dross.
Q. What is the general density of steel?
A. 6.67 g/cc
B. Q.87 g/cc
C. Q.77 g/cc
D. Q.77 g/cc
.
.Answer: B
Explanation: A steel is basically a mixture of iron and carbon. The composition of iron varies according to the alloy, high alloy steels contain more amounts of carbon and low alloy steels contain less amount of carbon. The density of steels in general is found to be Q.87 g/cc.
Q. What is the density of copper alloys?
A. 6.67 g/cc
B. Q.87 g/cc
C. Q.93 g/cc
D. Q.77 g/cc
.
..Answer: C
Explanation: A steel is a mixture of iron and carbon and copper alloys are mixtures of mainly copper and a few other materials like zinc and nickel with it. The main copper alloys can be brass and bronze. The density of copper alloys in general is found to be Q.93 g/cc.
Q. Which colour is obtained by copper alloys, when zinc is added to it?
A. Red
B. Blue
C. Silver
D. Yellow
.
.Answer: D
Explanation: It is one of the most unusual properties of copper alloys, that on addition of different materials in them, there is a change observed in its appearance, that is, the colour of the mixture starts changing. On addition of zinc metal in copper, the colour of the mixture changes to yellow.
Q. Which colour is obtained by copper alloys, when nickel is added to it?
A. Red
B. Blue
C. Silver
D. Yellow
.
..Answer: C
Explanation: None.
Q. What amount of impurity is allowed for copper to be used in electric applications?
A. 0.1%
B. 0.2%
C. 0.3%
D. 0.4%
.
Answer: A
Explanation: Copper and its alloys find themselves a variety of applications in the field of electrical and micro electrical works. For copper to be able to get used in electric appliances, the maximum impurity that can be allowed is 0.1%.
6. Which of the following materials, on adding with copper, doesn’t increase its strength?
A. Cadmium
B. Silver
C. Sodium
D. Aluminium Oxide
.
..Answer: C
Explanation: Copper originally does not possess a very high amount of strength. For properties of copper to be used, but with more strength, this copper needs to be mixed with certain material, which will provide it the required strength. Cadmium, silver and aluminium oxide are few of those materials which will aid in increasing its strength.
Q. What is the tensile strength of cast manganese bronze?
A. 490 MPa
B. 759 MPa
C. 676 MPa
D. 324 MPa
.
Answer: A
Explanation: 759 mega pascals is the tensile strength of quenched and tempered copper-aluminium alloy. 676 MPa is the tensile strength of cold worked zinc. 324 MPa is the tensile strength of annealed zinc and 490 MPa is the tensile strength of cast manganese bronze.
Q. What is the tensile strength of pure annealed copper?
A. 324 MPa
B. 676 MPa
C. 759 MPa
D. 209 MPa
.
.Answer: D
Explanation: None.
Q. Copper alloys are mostly hot treated?
A. True
B. False
.
.Answer: B
Explanation: For properties of copper to be used, but with more strength, this copper needs to be mixed with certain material, which will provide it the required strength. Cadmium, silver and aluminium oxide are few of those materials which will aid in increasing its strength. This process of increasing strength is done by treating the alloy through cold working.
Q. Iron needs higher temperature ranges for its extraction.
A. True
B. False
.
Answer: A
Explanation: The metal copper has its occurrence in large quantities. This material can be successfully extracted from the mines before the iron is extracted, the reason being, copper extraction happens at lower temperatures.
Q. For protection of copper alloys from corrosion, a special type of coating is applied on it.
A. True
B. False
.
.Answer: B
Explanation: No any special protective treatments are required for copper alloys against corrosion, as they have capability to protect themselves from corrosion. For the sea water applications, copper alloys are used which have high resistance to corrosion and chloride which is present in sea water in an abundant amount.
Q. Which of the following parts are mostly manufactured by using copper alloys?
A. Pistons
B. Engine blocks
C. Journal bearings
D. Aircrafts
.
..Answer: C
Explanation: In the manufacturing of journal and other types of solid bearings, copper alloys are mostly preferred. Many other components like worm wheels, gear selector forks and electricity wires are also made by using copper alloys; it is mostly preferred where low friction and high wear resistance is required.
Q. Copper alloys generally have sparking nature due to its high ductility.
A. True
B. False
.
.Answer: B
Explanation: Copper alloys components are generally of non-sparking nature, that’s why they are preferred in manufacturing of electrical equipment and components where there is a chance of fire hazard. And the ductile nature of copper alloys is totally independent to its non-sparking nature.
Q. Copper alloys have low thermal conductivity but high electrical conductivity.
A. True
B. False
.
.Answer: B
Explanation: Copper alloys have high thermal conductivity as well as high electrical conductivity. Due to high electrical conductivity, they are used in making of electric wires, in motor winding etc. And high thermal conductivity of copper alloys useful in making of heat exchangers, in piping of power-plants, air conditioning, refrigerators etc.
Q. Copper alloys possess good mechanical properties even at high temperatures.
A. True
B. False
.
Answer: A
Explanation: Copper and its alloys have an optimized combination of tensile and compressive strength, hardness, ductility and resistance to shock load to use for various applications. And the mechanical properties of copper alloys at high temperatures are even better than the other non-ferrous materials.
6. At zero level temperature of copper alloys, they become very hard and brittle in nature.
A. True
B. False
.
.Answer: B
Explanation: At zero level temperature of copper alloy castings, no any kind of embrittlement occurs; in fact, the tensile strength of copper castings enhances at low temperature. Therefore, the copper castings can be used at very low temperatures without any significant changes to the properties of the castings.
Q. Castings or components of copper alloys have high machinability and recyclability.
A. True
B. False
.
Answer: A
Explanation: Many alloys consist of lead to increase machinability with easy chip formation. But, copper components itself have excellent machinability. And copper alloy castings are recyclable too, the scrapes of copper alloys castings can be melted and can be used again in the manufacturing of other copper parts.
Q. In general, copper is highly reactive with sulphur and its chemical compounds.
A. True
B. False
.
Answer: A
Explanation: Copper may resists the oxidation, but it is highly reactive with sulphur and its chemical compounds, it produces copper sulphide during the reaction which can be unpleasant for the casting components. The main copper contaminants significantly are phosphorous and iron besides oxygen.
Q. Copper is generally a polymorphous material with body centered cubic (BCC. lattice structure.
A. True
B. False
.
.Answer: B
Explanation: Copper is a non-polymorphous material with face centered cubic (FCC. structure. The FCC structure is the only reason for ductility in the copper material. Pure copper is generally reddish in color, and addition of zinc produces the yellow color of the copper and nickel produces the silver color of the same.
Q. It is very difficult to cast pure copper metal in mould cavity because of shrinkage problems.
A. True
B. False
.
Answer: A
Explanation: It is very difficult to cast pure copper in mould cavity because very large shrinkages occur during the solidification of castings, and a large amount of gasses are trapped in the casting at high temperatures which results in the melted material gassing and the porosity in casting components.
Q. Pure magnesium melts at what temperature?
A. 600°C
B. 650°C
C. 700°C
D. 750°C
.
.Answer: B
Explanation: The temperature at which the pure form of magnesium gets ignited by itself is 473°C, and the temperature at which magnesium in its purest form is found to melt is 650°C.
Q. Which of the following metals is least used in making magnesium alloys?
A. Aluminium
B. Zinc
C. Copper
D. Manganese
.
..Answer: C
Explanation: Magnesium metal in itself is not one of the strongest metals and is hence adulterated with other materials to form strong alloys. Among the following, aluminium, zinc and manganese are highly used in making magnesium alloys.
Q. Which of the following can be the casting temperature for magnesium alloys?
A. 630°C
B. 760°C
C. 850°C
D. 970°C
.
.Answer: B
Explanation: When it comes to casting of magnesium alloys, the casting temperatures have to be kept in real control, that is, if the temperatures go too high, the metal might catch fire. The temperature range for casting magnesium alloys is 720°C to 800°C.
Q. Which of the following is not a property of a magnesium alloy?
A. High damping capacity
B. High electrical conductivity
C. Good fatigue strength
D. High thermal resistivity
.
.Answer: D
Explanation: Magnesium on getting mixed with other elements starts possessing many different properties. It contains good damping capacity, good electrical conductivity and good fatigue strength, but not, thermal resistivity.
Q. What is the color of pure magnesium metal?
A. Red
B. White
C. Black
D. Yellow
.
.Answer: B
Explanation: The purest form of magnesium is considered to be in its weakest form, and hence other elements are added in it to enhance its quality. The physical qualities too change on addition of other elements. Originally, the color of pure magnesium metal is silvery white.
6. What should be the temperature of the mixture while alloying takes place?
A. 550°C
B. 600°C
C. 650°C
D. 700°C
.
.Answer: D
Explanation: During the mixture getting processed, first the magnesium is melted, and then zinc metal is added. Aluminum is mixed in it through stirring. While this is happening, it has to be ensured, that the complete alloying process takes place at 700°C.
Q. In magnesium alloys, what is the maximum amount of allowed aluminum?
A. 11%
B. 13%
C. 19%
D. 24%
.
Answer: A
Explanation: Magnesium alloys are basically a composition of various metals mixed with magnesium to improve its physical, chemical, mechanical and thermal properties. In this, the maximum allowable aluminum that can be added is only 11%.
Q. What should the temperature ideally be to remove the casting after making of magnesium alloys?
A. Below 450°C
B. Below 300°C
C. Below 350°C
D. Below 300°C
.
.Answer: D
Explanation: It is always advisable that the castings should never be removed too quickly, as it might lead to distortion of the cast because it is still hot. Therefore, when the temperature of the cast is below 300°C, the magnesium alloy cast can be removed.
Q. In grain refinement process, only hexachlorobenzene is used.
A. True
B. False
.
Q. Magnesium alloys have a low strength to weight ratio.
A. True
B. False
.
.Answer: B
Explanation: Magnesium alloys possess many desirable mechanical, physical and thermal properties, which may help in better casting processes. One of these properties is a high strength to weight ratio.
1Q. In sand casting of magnesium alloys, what is the amount of silica sand used in an American mix?
A. 80 lb
B. 90 lb
C. 100 lb
D. 110 lb
.
..Answer: C
Explanation: It is mainly observed that magnesium alloys are manufactured with the help of sand molds only. The amount of silica sand used in magnesium alloys is 100 lbs in both the British mix and the American mix.
1Q. In sand casting of magnesium alloys, what is the amount of bentonite sand used in a British mix?
A. 3 lb
B. 4 lb
C. 5 lb
D. 6 lb
.
.Answer: B
Explanation: In the production of magnesium alloys, there are a variety of sands employed. For this, bentonite sand has to be used for the sand casting of the alloys. The amount of bentonite sand used is 4 lbs in both British as well as American mix.
Q. In general, magnesium alloy components tends to have fine grain structure in it.
A. True
B. False
.
.Answer: B
Explanation: In general, magnesium alloy component tends to have coarse grain structure unless some suitable procedures are taken to insure the formation of fine grains. The procedure involves superheating of molten metal to 2500 or 3000 ⁰C. And then after holding it there for a certain period of time, it cools down to the desired temperature and pouring operation takes place without any delay.
Q. Magnesium is a very light material that can be suitable in aircraft applications.
A. True
B. False
.
Answer: A
Explanation: Magnesium is very light metal in comparison with other structural metals. Magnesium is commonly used in a wide range of markets and applications, from automobiles to aircraft applications. In most of the cases of manufacturing, weight reducing is the primary objective for magnesium alloys.
Q. Magnesium metal is very light material, but not lighter than aluminium metal.
A. True
B. False
.
.Answer: B
Explanation: Magnesium is mainly distinguished by its low density, which is nearly about 25% of steel and about 60% of the aluminium metal. This property makes magnesium to use for very lightweight construction. In expensive cars, it is highly used in the construction of crankcase and in other parts to increase power to weight ratio.
Q. Magnesium cannot be used extensively for precision casting applications.
A. True
B. False
.
Answer: A
Explanation: Magnesium cannot be used extensively for precision casting applications because it is highly reactive with silica containing constituents like plaster or other mould materials. Silica is mostly present in slurry in which it acts like binding material. Reaction of magnesium with silica produces magnesium oxide and magnesium silicide which may imparts defects in the casting components.
Q. Adding of zirconium in magnesium metal results in the formation of magnesium-zirconium alloy of enhanced ductility.
A. True
B. False
.
.Answer: B
Explanation: The grain size is highly affected by adding zirconium in magnesium metal. Addition of less than 0.6% zirconium in magnesium is sufficient to obtain grain size less than 80 microns in casted components. This further increases hardness in the material due to formation of fine grains and ductility also decreases simultaneously.
6. Inhibitors are generally used in mould to avoid reaction of magnesium with moulding materials.
A. True
B. False
.
Answer: A
Explanation: When moulding materials like silica, moisture and binders make contact with magnesium, the reaction takes place which arise problems in the castings of magnesium alloys. To avoid reaction, the mould is modified by using some techniques like drying and by including inhibitors in the moulding materials.
Q. Which of the following compounds can be used as an inhibitor in moulding materials for avoiding chemical reaction with magnesium alloys?
A. Sodium silicate
B. Water
C. Hydrogen silicate
D. Potassium borofluoride
.
.Answer: D
Explanation: Moulding materials are effectively inhibited by adding 1 to 2 percent of potassium borofluoride. And controlling of inhibitor content in moulding materials is very important because they can affect setting times. Sometimes elimination of silica content from moulding materials also takes place to avoid chemical reactions.
Q. Magnesium metal possesses better noise and vibration damping characteristics than aluminum.
A. True
B. False
.
Answer: A
Explanation: Magnesium is the lightest material in all the engineering materials. It has good ductility, better noise and vibration damping features than aluminium and also has excellent cast-ability. Alloying of magnesium metal with aluminium, manganese increases the strength of the components and also reduces the weight of the casted parts, so magnesium alloys are very important materials for applications where weight saving is a dominant objective.
Q. Magnesium alloys do not require any special coating as they are self protective from corrosion.
A. True
B. False
.
.Answer: B
Explanation: Different types of coatings are applied to magnesium alloys to increase corrosion resistance. Coatings for magnesium alloys are applied by using hexavalent chromium material which provides excellent protection, but do not considered as eco-friendly. To avoid environmental problems, Teflon resin is basically applied instead of any other coatings.
Q. Teflon resin coating can be used to increase the lubricity of magnesium alloys.
A. True
B. False
.
Answer: A
Explanation: Teflon resin is a low cost coating which is primarily used for magnesium alloys to improve corrosion resistant properties. It is a chromium free corrosion resistant coating that can be also used for improving lubricity and frictional resistance. It also includes non-wetting features which keeps the casting moisture free.
Q. The mixing of flux in the casting material produces endothermic reaction.
A. True
B. False
.
.Answer: B
Explanation: The flux is mixed with casting while solidification that basically reacts with a network of oxides and converts them into a powder that floats on the casting so it becomes easier to separate out that part. The whole reaction takes place is exothermic. The flux is normally used after the cleaning process which prevents progressive oxidation.
Q. Which of the following materials are commonly used as flux in the casting process to prevent oxidation?
A. Sodium silicate
B. Lead
C. Sodium chloride
D. Sodium carbonate
.
..Answer: C
Explanation: Sodium chloride is commonly used as flux in the casting process to prevent oxidation. Sometimes potassium fluoride is also preferred as a flux due to its excellent volatility. It not only prevents the oxidation, the other inclusions are also reduced by using flux. This process avoids metal wastage and avoids several defects formation.
Q. Degassing process during the formation of castings can prevent inclusion of hydrogen absolutely.
A. True
B. False
.
.Answer: B
Explanation: After degassing process, the hydrogen does not stop coming in the casting material. This can only be controlled by using fluxes in the casting material but it is always recommended to determine the gas quantity before casting process, a device called reduced pressure gas determination equipment is then used for determining the gas content.
Q. What should be the melting point (in ⁰C. of flux used for mixing with aluminium casting?
A. 440⁰C
B. 555⁰C
C. 606⁰C
D. 660⁰C
.
.Answer: D
Explanation: The melting point for flux to be used for aluminium casting should be approximately 660⁰C. However, the oxidation in aluminum is inevitable but flux is essential to avoid contact of aluminium melt to atmosphere and to get dry dross after skimming process which generally maintains the quality of casting material.
Q. The fluxes used in the casting process must have low vapour pressure.
A. True
B. False
.
Answer: A
Explanation: If the flux has high vapour pressure then it will not be easy to control it as vapourization will takes place which will have no any affect on the casting material. So it is always suggested to have low vapour pressure of fluxes that will easily mix with the material and will give excellent results in order to prevent oxidation.
6. Which of the following devices is mainly used for thermal analysis of flux?
A. Thermocouple
B. Thermometer
C. Thermo resister
D. Spiral optical tube
.
Answer: A
Explanation: The flux is first melted inside a crucible and then a thermocouple is inserted into the molten flux. After the cooling process of molten flux, the temperature variations are recorded with respect to time. The melting nature, the variation in viscosity and the melting range of the molten flux with temperature is recorded.
Q. Refractory materials are basically used for strengthening the casting materials used in the casting process.
A. True
B. False
.
.Answer: B
Explanation: Refractory materials are materials that have high melting points and they basically act as a heat resisting barrier between high and low temperature zones. Refractory materials are useful in constructing structures like boilers, furnaces etc. as they minimize heat losses through the structure during working conditions.
Q. Refractories are generally inorganic non-metallic materials which can resist very high temperature.
A. True
B. False
.
Answer: A
Explanation: Refractories are inorganic nonmetallic materials which can resist very high temperature without any physical or chemical variations. It is essential to generate a certain range of refractory materials with different features to be resistant to thermal shock, be chemically inert and to possess good thermal conductivity.
Q. Silicon carbide is widely used as refractory material in the mould making for casting processes.
A. True
B. False
.
.Answer: B
Explanation: Silicon carbide is a good refractory material, but cannot be used in mould making process because it is highly reactive with oxygen and gets burns itself during oxidation. To avoid such oxidation problems, zirconia is preferred which can also bear very high temperatures and perfectly acts as a refractory material.
Q. Refractoriness of a material should always be greater than its application temperatures.
A. True
B. False
.
Answer: A
Explanation: Refractoriness is a property at which a refractory material deforms under its own load. The refractoriness is generally indicated by Pyrometric cone equivalent (PCE). It should always be greater than the application temperatures. Refractoriness is decreased when the refractory material is continuously under loading conditions.
Q. In general, titanium is denser than steel due to compactness in grain structure of titanium.
A. True
B. False
.
.Answer: B
Explanation: Titanium is a low density material which is approximately 60% of the density of steel. It is mainly strengthened by alloying and deformation methods. It is a nonmagnetic metal which has low thermal conductivity. Its coefficient of thermal expansion is generally less than that of steel and less than half that of aluminium.
Q. Titanium alloys have melting point greater than that of steels.
A. True
B. False
.
Answer: A
Explanation: Titanium alloys have melting point greater than that of steels, but maximum temperatures for various applications normally range from 428 °C to approximately 540 °C. It mainly depends upon the composition and its characteristics. Titanium aluminide alloy can achieve temperature up to 760 °C for some applications.
Q. Titanium is a toxic material which can also be affected by the attack of chlorides or mineral acids.
A. True
B. False
.
.Answer: B
Explanation: Titanium has the ability to un-react with any coating or material, so thereby it shows a high degree of resistance against the attacks of chlorides and mineral acids. Pure titanium is a nontoxic material, so its alloys and it can be compatible with human tissues and bones biologically without any significant effects to the human body.
Q. The properties of titanium can remain constant with abrupt variations in the temperature of a material.
A. True
B. False
.
Answer: A
Explanation: Titanium has good properties like strength, low-thermal expansion with low modulus with respect to its low-high cycle of fatigue strength, corrosion resistance, and weld-ability. Titanium is the only material that includes this combination of properties over a temperature range starting from the surrounding temperature to approx 550 ⁰C.
Q. Which of the following materials is the most dominant in aero engine applications?
A. Iron
B. Brass
C. Titanium
D. Copper
.
..Answer: C
Explanation: Titanium is the single material which is very dominant in compressor stages of aero engine applications. Aluminium and steel can also be used, but the use of titanium is very effective. Its alloys greatly improve the aerodynamic cycle and propulsive efficiency also with improvements in thrust to weight ratio.
6. Melting and casting of titanium are very difficult due to its high chemical reactivity with mould materials.
A. True
B. False
.
Answer: A
Explanation: Many problems arise in process of melting and casting of titanium due to its great chemical reactivity with mould material and its great affinity for surrounding gases. To avoid such problems, graphite or investment moulding is preferred which are also difficult but possible to produce equipment in aero engine and biomedical applications.
Q. In general, titanium castings exhibits excellent fatigue strength due to its high rigidity.
A. True
B. False
.
.Answer: B
Explanation: Titanium castings generally have beta structure which is combined with excellent creep resistance, fatigue crack resistance and tensile properties. But the titanium castings exhibits very low fatigue strength due to the presence of porosities in the castings. These porosities can be treated by isostatic pressing to improve properties of the titanium castings.
Q. Refractory oxides do not have any effect on molten titanium metal at the time of casting process.
A. True
B. False
.
.Answer: B
Explanation: Most of the refractory oxides like zirconia and alumina react with molten titanium to generate a layer which is enriched in oxygen or inter-metallic compounds of titanium. The oxide mixes in molten titanium which gives rise to a contaminated layer that can be considered as precipitate as a separate phase on cooling.
Q. Which of the following methods of melting is not used for melting titanium metal?
A. Induction method
B. Vacuum arc method
C. Electron beam melting
D. Cupola furnace melting
.
.Answer: D
Explanation: Various melting methods are used for melting of titanium metal. For example, induction, vacuum arc and electron beam melting, in which vacuum arc and electron beam melting methods are widely used, though efforts are made continuously for producing other different methods to gain better control on melting and to have better utilization of scrap materials. And cupola furnace is basically used for melting iron alloys.
Q. Titanium metal generally has a high melting point and low thermal conductivity.
A. True
B. False
.
Answer: A
Explanation: Titanium metal has a high melting point and low thermal conductivity which is responsible for producing a steep thermal gradient in the casting during solidification. The reaction with mould materials forms surface layers which include oxygen and other elements taken from the mould. This affects the mechanical properties of the castings. So to avoid such problems, graphite or investments moulds are used instead of simple moulds.
Q. How is much amount of chromium (in percent) normally added in steel to be called as stainless steel?
A. 1-2 %
B. 2-5 %
C. 5-10%
D. 10-30 %
.
.Answer: D
Explanation: Stainless steels mainly contain 10-30 % of chromium besides other elements such as carbon, manganese, silicon, sulphur etc. Chromium produces corrosion resistance property in steel, that’s why the material is known as stainless steel as no any kind of stains are occur on the surface of the steel.
Q. Which of the following types of stainless steels contain maximum amount of chromium in it?
A. Duplex stainless steels
B. Martensitic stainless steels
C. Austenitic stainless steels
D. Precipitation hardenable stainless steels
.
Answer: A
Explanation: Duplex stainless steels contain approximately 25 % of chromium while rest of the stainless steels contain less than that of duplex stainless steels. All the stainless steel materials contain chromium and carbon besides other elements. In production of stainless steels, controlling of carbon and chromium content should be proper.
Q. In the manufacturing of stainless steel, oxidation of carbon and chromium cannot be possible.
A. True
B. False
.
.Answer: B
Explanation: In the manufacturing of stainless steel, both chromium and carbon can be oxidized due to decarburization of molten casting. Carbon oxidation in comparing with chromium oxidation may occur at temperature above 1220 ⁰C in the pure state conditions. But experimentally, carbon oxidation can occur at temperature above 1800 ⁰C than that of chromium.
Q. Which of the following materials is required in a technique of decarburizing the molten steel?
A. Calcium carbonate
B. Sodium chloride
C. Carbon ferrochrome
D. Sodium ferrochrome
.
..Answer: C
Explanation: Decarburization technology uses high carbon ferrochrome to decarburize the molten steel at lower temperatures. If carbon oxidizes first with respect to chromium at low temperatures, then the reduction in pressure from atmosphere to a lower value will be required. Reduction in pressure is mostly done by vacuum oxygen decarburization (VOD. method.
Q. In argon oxygen decarburization (AOD. method, whole process is carried out in a converter type of vessel.
A. True
B. False
.
Answer: A
Explanation: The argon oxygen decarburization (AOD. process is mainly carried out in a converter type of vessel which is generally lined up with magnesite bricks. Then a combination of argon and oxygen is filled by the application of tuyeres located on the side of the converter vessel. Then the melt of steel is charged into the vessel for further processing.
6. Preheating of scrap material in steel making process can increase the overall productivity.
A. True
B. False
.
Answer: A
Explanation: The energy required for steel making in the electric vessel is mainly for the melting down of scrap material. Preheating of scrap material can reduce the energy requirement which further reduces the time in making of steel that can directly increase the overall productivity. Other advantages include decrease in electrode consumption and the refractory wear.
Q. The dust produced from electric furnaces in steel making procedure is directly thrown out to the atmosphere via chimney.
A. True
B. False
.
.Answer: B
Explanation: In steel making, dust is produced in the electric furnace during melting of steel. The produced dust is carried away in the off-gases which basically contains iron and some non-ferrous materials like zinc and lead. So not only environmental considerations but also for the economic considerations, the dusts are collected and recovery of valuable materials is done.
Q. Obsolete scrap is the scrap which is relatively pure and its chemical composition is known.
A. True
B. False
.
.Answer: B
Explanation: Obsolete scrap generally contains iron and steel parts which are rejected due to end of their service life. It is often mixed with other metals like copper, zinc and tin to form other steel alloys. And home scrap is known as the scrap which is relatively pure and chemical composition is known.
Q. Steel yield is highest in continuous casting method which significantly reduces scraps.
A. True
B. False
.
Answer: A
Explanation: It is always aimed to have higher steel yield in steel industries through attributes of equipment and technologies used in steel making. The steepest decrease in the amount of scraps is mainly achieved by the application of continuous casting method which has highest casting or steel yield.
Q. Copper cannot be removed from steel scraps by the method of conventional refining.
A. True
B. False
.
Answer: A
Explanation: It is not possible to remove copper from steel scraps by the method of conventional refining. It can be removed by treating steel scraps with sulphide fluxes and also by treating it at reduced pressure of the gas phase which basically includes vapourization of copper from the steel scraps.
Q. The term degassing is basically employed for optimizing the use of materials used in production of casting components.
A. True
B. False
.
.Answer: B
Explanation: During production of casting products, gases such as oxygen, hydrogen and nitrogen get dissolved in the casting. The term degassing is employed for the removal of these gases from the casting melt. Dissolved oxygen from molten casting cannot be extract as molecular oxygen, removing of oxygen from melt is called as de-oxidation.
Q. Excess of nitrogen in molten casting can cause embrittlement of casting components.
A. True
B. False
.
Answer: A
Explanation: During solidification of molten casting in mould cavity, excess of nitrogen is extracted from the melt which can cause blow holes and embrittlement of heat affected zone of casting component. So, it is very necessary to remove nitrogen from the melt to produce castings of desired quality and defects free.
Q. The presence of hydrogen in molten casting strengthens the casting components.
A. True
B. False
.
.Answer: B
Explanation: Solubility of hydrogen in the melt is generally low at ambient temperature. Hydrogen in molten casting damages or weakens the mechanical properties which also results in occurrence of porosity and losing of tensile ductility in the casting parts. Thus, removal of excess hydrogen is very necessary during solidification of the molten casting.
Q. Degassing can be carried out by placing ladle containing liquid metal under vacuum.
A. True
B. False
.
Answer: A
Explanation: In ladle degassing method, the effectiveness is reduced from top to bottom of the molten metal. Bottom layers of metal are not much affected by the vacuum as these layers influenced by the pressure due to column of liquid metal. So the entire molten metal content is exposed to the vacuum for the complete degassing operation.
Q. Which of the following gases is used in the method of recirculation degassing?
A. Hydrogen
B. Nitrogen
C. Argon
D. Oxygen
.
..Answer: C
Explanation: In the method of recirculation degassing, argon gas is used which is bubbled through the porous holes located at the bottom side of ladle. The speed of degassing will increases with the increase in rate of circulating the liquid metal through the vacuum region. And the circulating speed is increased by the increase in flow rate of argon gas.
6. Which of the following formulas is used for determining the circulation rate (R) in recirculation degassing?
A. R = Q.42*103*Q1/3*d1/3*{ln(P1/P2)}
B. R = Q.42*103*Q1/3*d1/3*{ln(P1/P2)}
C. R = Q.14*103*Q1/3*d1/3*{ln(P1/P2)}
D. R = Q.42*103*Q1/3*d1/3*{ln(P1/P2)}
.
.Answer: D
Explanation: The circulation rate (R) in recirculation degassing is given by-
R = Q.42*103*Q1/3*d1/3*{ln(P1/P2)} , where R is the circulation rate in Kg/sec, Q is the injection rate of argon gas, P1 is the pressure at the base, P2 is the pressure in the vacuum chamber and D is the internal diameter.
Q. The effectiveness of vacuum treatment is reduced by the increase in surface area of the molten metal exposed to vacuum.
A. True
B. False
.
.Answer: B
Explanation: The effectiveness of vacuum treatment is always increased by the increase in surface area of the molten metal exposed to vacuum. The increased surface area of the molten metal exposed to the vacuum; for example, in the form of a thin gas induced stirs which can accelerate the degassing operation. And the degassing time should be kept minimum as much as possible.
Q. In vacuum treatment of molten metal, temperature of the melt can be decreased.
A. True
B. False
.
Answer: A
Explanation: Temperature of melt decreases during the vacuum treatment of molten metal. This is basically caused by exposing of more surface area to the vacuum chamber. To maintain the heat from the molten metal additional heating of the metal is usually done to compensate for the loss of heat.
Q. In vacuum degassing method, low viscosity is considered to have negative influence on the reaction rate.
A. True
B. False
.
.Answer: B
Explanation: The viscosity influences the efficiency of vacuum degassing; a high viscosity is considered to have negative influence on the reaction rate. The viscosity is generally not considered in the kinetics; instead, a constraint is used that limits the viscosity to be below 0.5 Pas. The melt should have low viscosity which also reduces the time involved in the procedure.
Q. The effect of temperature change is generally neglected during the vacuum degassing process.
A. True
B. False
.
Answer: A
Explanation: The reduction in temperature changes the composition of equilibrium steel and hence mass transfer coefficient changes dynamically. The effect of temperature change is generally neglected during the vacuum degassing process, but the temperature change is analyzed so that the operation does not finish at the low temperatures.
