Corrosion Engineering Mcqs

Q:

Which of the following is/are the limitations of high-temperature non-metallic materials?

A) Lack of ductility B) Less resistance to thermal shock
C) Weldability, less resistance to thermal shock, lack of ductility and formability D) Weldability and formability
 
Answer & Explanation Answer: C) Weldability, less resistance to thermal shock, lack of ductility and formability

Explanation: Limitations of high-temperature non-metallic materials are:
i. Lack of ductility
ii. Less resistance to thermal shock
iii. Lack of ductility
iv. Formability
v. Weldability.

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17
Q:

Which of the following is/are the high melting point metals?

A) Molybdenum B) Tungsten
C) Columbium D) Molybdenum, tungsten, columbium, and tantalum
 
Answer & Explanation Answer: D) Molybdenum, tungsten, columbium, and tantalum

Explanation: Metals – Melting points
i. Tungsten – 6170°F
ii. Tantalum – 5430°F
iii. Molybdenum – 4750°F
iv. Columbium – 4380°F.

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19
Q:

Which of the following nickel-based alloys is/are superalloys?

A) Hastelloy C-276 B) Inconel 718
C) Hastelloy C-276, Inconel 718 and Hastelloy HX D) Hastelloy HX
 
Answer & Explanation Answer: C) Hastelloy C-276, Inconel 718 and Hastelloy HX

Explanation: Superalloys or high-performance alloys are the alloys that can resist extreme conditions such as high temperature, high stress, high wear, and corrosive atmospheres. Nickel-based alloys are widely used as superalloys that include Hastelloy C-276, Inconel 718, and Hastelloy HX.

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20
Q:

Which of the following metallurgical changes that affect the structural stability of metals at high temperatures?

A) Grain growth, phase changes, precipitation dissolution and precipitation over aging B) Grain growth and phase changes
C) Precipitation dissolution and precipitation over aging D) Phase changes, precipitation dissolution and precipitation over aging
 
Answer & Explanation Answer: A) Grain growth, phase changes, precipitation dissolution and precipitation over aging

Explanation: Metallurgical changes that affect the structural stability of metals at high temperature are:
i. Grain growth
ii. Phase changes
iii. Precipitation dissolution
iv. Precipitation over aging.

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21
Q:

Which of the following strengthening mechanisms is/are used to attain high-temperature strength?

A) Solid-solution strengthening B) Precipitation hardening
C) Dispersion hardening D) Solid-solution strengthening, precipitation hardening or dispersion hardening
 
Answer & Explanation Answer: D) Solid-solution strengthening, precipitation hardening or dispersion hardening

Explanation: Strengthening mechanism that is used to attain high-temperature strength are:
i. Solid-solution strengthening
ii. Precipitation hardening
iii. Dispersion hardening.

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25
Q:

Which of the following is/are the adequate high-temperature mechanical properties to avoid fracture?

A) Low creep rate and high stress-rupture strength B) High stress-rupture strength, low creep rate, and high fracture toughness
C) High stress-rupture strength and high fracture toughness D) Low creep rate and high fracture toughness
 
Answer & Explanation Answer: B) High stress-rupture strength, low creep rate, and high fracture toughness

Explanation: Low creep rate, high stress-rupture strength, and high fracture toughness are the adequate high-temperature mechanical properties to avoid fracture.

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20
Q:

Which of the following is/are true regarding stress rupture?

A) The stress required to cause a rupture in a predetermined time at a constant temperature B) It is important in short-term high-temperature applications
C) Stress rupture is an important mechanical property for gas turbine or rocket engines D) The stress required to cause a rupture in short-term high-temperature applications at a predetermined time is known as stress rupture and it is an imp
 
Answer & Explanation Answer: D) The stress required to cause a rupture in short-term high-temperature applications at a predetermined time is known as stress rupture and it is an imp

Explanation: Stress rupture is defined as the amount of stress that is required to cause a rupture in short-term high-temperature applications at a predetermined time. It is an important mechanical property for gas turbines and rocket engines.

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25
Q:

Which of the following is/are correct regarding creep?

A) It is the continuous plastic elongation of metal under constant load B) It is the high-temperature mechanical effect of a metal
C) It is the continuous plastic elongation of metal under constant load at high temperature and it can be minimized by the fraction of grain boundaries D) It can be minimized by reducing the fraction of grain boundaries
 
Answer & Explanation Answer: C) It is the continuous plastic elongation of metal under constant load at high temperature and it can be minimized by the fraction of grain boundaries

Explanation: It is defined as the continuous plastic elongation of metal under constant load at high temperatures. Creep rate is then expressed as percent elongation in a given time. It can be minimized by reducing the fraction of grain boundaries.

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