Engineering Materials MCQ Questions & Answers

31

Thermoplastic materials are those materials which

A) Are formed into shape under heat and pressure and results in a permanently hard product B) Do not become hard with the application of heat and pressure and no chemical change occurs C) Are flexible and can withstand considerable wear under suitable conditions D) Are used as a friction lining for clutches and brakes

Discuss

Answer & Solution

Answer: Option B

Solution:

Thermoplastic materials can be cooled and heated several times without any change in their chemistry or mechanical properties.
A thermoplastic, or thermosoftening plastic, is a plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.

32

Admiralty brass used for steam condenser tubes contains copper and zinc in the following ratio

A) 50 : 50 B) 30 : 70 C) 70 : 30 D) 40 : 60

Discuss

Answer & Solution

Answer: Option C

Solution:

The correct answer is Option C: 70 : 30.
Let's break down why:
Admiralty brass is a specific type of brass alloy.
Brass is primarily made of copper and zinc.
Admiralty brass has a typical composition of approximately 70% copper and 30% zinc, and also contains a small amount of tin (around 1%) to improve corrosion resistance, especially in seawater applications like steam condensers.
Therefore, the ratio of copper to zinc in admiralty brass is closest to 70:30.
The other options are incorrect because they do not reflect the standard composition of admiralty brass.

33

Alnico, an alloy used extensively for permanent magnets contains iron, nickel, aluminium and cobalt in the following ratio

A) 50 : 20 : 20 : 10 B) 40 : 30 : 20 : 10 C) 50 : 20 : 10 : 20 D) 30 : 20 : 30 : 20

Discuss

Answer & Solution

Answer: Option A

Solution:

The composition of alnico alloys is typically 50% of Iron, 20% of nickel,20% of aluminium and 10% of cobalt

34

Heavy duty leaf and coil springs contain carbon of the following order

A) 0.2% B) 0.5% C) 0.8% D) 1.0%

Discuss

Answer & Solution

Answer: Option D

Solution:

Heavy duty leaf and coil springs contain 1.0% carbon

35

Cold rolled steel sheets contain carbon of the following order

A) 0.1% B) 0.2% C) 0.4% D) 0.6%

Discuss

Answer & Solution

Answer: Option A

Solution:

Cold rolled steel sheets contains 0.1% carbon
Cold Rolled Steel A rolling process at temperatures that are close to normal room temperature are used to create cold rolled steel. This increases the strength of the finished product through the use of strain hardening by as much as 20 %

36

In full annealing, the hypo eutectoid steel is heated from 30°C to 50°C above the upper critical temperature and then cooled

A) In still air B) Slowly in the furnace C) Suddenly in a suitable cooling medium D) Any one of these

Discuss

Answer & Solution

Answer: Option B

Solution:

In full annealing, the hypo eutectoid steel is heated from 30°C to 50°C above the upper critical temperature and then cooled Slowly in the furnace

37

Steel containing ferrite and pearlite is

A) Hard B) Soft C) Tough D) Hard and tough

Discuss

Answer & Solution

Answer: Option B

Solution:

Steel containing ferrite and pearlite is soft.
Ferrite is a form of pure iron with a body-centered cubic crystal structure and occurs in low-carbon steel.
Pearlite is a finely laminated mixture of ferrite and cementite present in cast iron and steel, formed by the cooling of austenite.

38

Ductile cast iron

A) Contains 1.7 to 3.5% carbon in Free State and is obtained by the slow cooling of molten cast iron B) Is also known as chilled cast iron and is obtained by cooling rapidly. It is almost unmachinable C) Is produced by annealing process. It is soft, tough and easily machined metal D) Is produced by small additions of magnesium (or creium) in the ladle. Graphite is in nodular or spheroidal form and is well dispersed throughout the material

Discuss

Answer & Solution

Answer: Option D

Solution:

Ductile cast iron Is produced by small additions of magnesium (or creium) in the ladle. Graphite is in nodular or spheroidal form and is well dispersed throughout the material
ductile iron has much more impact and fatigue resistance, due to its nodular graphite inclusions.

39

Which of the following steel making process is being adopted at Rourkela (in India) Steel Plant?

A) Bessemer process B) Open hearth process C) Electric process D) LD process

Discuss

Answer & Solution

Answer: Option D

Solution:

LD process is a steel making process is being adopted at Rourkela (in India) Steel Plant

40

Quenching is not necessary when hardening is done by

A) Case hardening B) Flame hardening C) Nitriding D) Any one of these

Discuss

Answer & Solution

Answer: Option C

Solution:

Nitriding has a different hardening mechanism than the one caused by quenching a steel with an elevated level of carbon.
Instead, the hardening is caused by the fine scale precipitation of alloying element nitrides which does not require quenching.

Engineering Materials MCQ Questions & Answers | Mechanical Engineering