This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Miscellaneous Alloying Elements – 1”.
1. Which element is known as the softest heavy metal?
Explanation: Lead is the oldest of the commonly used metals and is the softest of the heavy metals. It is a poisonous element. Lead has an FCC crystal structure.
2. What is the melting point of lead?
Explanation: Lead is a heavy metal with a low melting point of 327 and a boiling point of 1749. It has a density of 11.34 kg/dm3. Lead also possesses low strength, hardness, and elasticity.
3. What is the appearance of lead?
Explanation: When lead is cast or cut, it initially appears in lustrous silvery-blue color. However, after some time, it turns into a metallic-grey element. This is due to the oxidation process when it is exposed to air.
4. Lead alloys containing _______ lead are used as bearing metals.
Explanation: Bearing metals are anti-friction materials which may be derived from lead alloys containing 8-10% lead. Lead compounds include red lead and white lead.
5. Bearing metals are called Babbit metals on the addition of ________
Explanation: Bearing metals, composed of lead and tin alloys, are used for friction bearings. When antimony is added, they are known as Babbit metals. Addition of antimony makes the alloy hard.
6. The melting point of nickel is _________
Explanation: Nickel is a metal having a melting point of 1453oC and a boiling point of 2730oC. It is silvery-gold in appearance and is lustrous.
7. What is a nickel-iron alloy, with 40-50% nickel, called?
Explanation: Invar is a trademark for an iron-nickel alloy containing 40-50% nickel. It possesses an extremely low coefficient of thermal expansion. It is used for making precision instruments, measuring tapes etc.
8. Addition of which element turns the Invar alloy into Elinvar alloy?
Explanation: Invar is an alloy of nickel and iron. However, when 12% of chromium is used instead of iron, it produces Elinvar alloy. It possesses a low coefficient of expansion and an invariable modulus of elasticity.
9. Which type of Monel alloy is a hard-casting grade?
a) K Monel
b) R Monel
c) H Monel
d) S Monel
Explanation: Monel is a nickel-based alloy with copper. H Monel is a hard-casting grade Monel. K Monel and S Monel are known as age-hardenable grade and age-hardenable casting grade respectively. R monel is a free machining grade.
10. How does a Monel perform compared to mild steel?
a) Brighter appearance
b) Stronger and tougher
c) Poor toughness
d) Poor strength
Explanation: Monel usually contains 66% Ni, 31.5% Cu, 1.35% Fe, and 0.9% Mn. They are stronger and tougher when compared to mild steel, and have excellent resistance to atmospheric and seawater corrosion. It has a brighter appearance when compared to nickel.
Sanfoundry Global Education & Learning Series – Engineering Materials & Metallurgy.
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