Engineering Materials - Study Mode

[#196] Which of the following elements does not impart hardness to steel?
Correct Answer

(A) Copper

Explanation

Solution: Copper is a soft, malleable and ductile metal with very high thermal and electrical conductivity and it is not impart hardness to steel.

[#197] The steel widely used for motor car crankshafts is
Correct Answer

(C) Nickel-chrome steel

Explanation

Solution: Option A: Nickel steel This statement is incorrect . While nickel steel is used for some applications requiring strength and toughness, it is not the most common steel used for motor car crankshafts. Nickel steel has good toughness and resistance to impact, but it does not offer the same overall performance as nickel-chrome steel in this specific application. Option B: Chrome steel This statement is incorrect . Chrome steel is a type of steel alloyed with chromium, which gives it high wear resistance and hardness. However, chrome steel alone does not have the ideal combination of strength and toughness required for motor car crankshafts. Option C: Nickel-chrome steel This statement is correct . Nickel-chrome steel is widely used for motor car crankshafts because it combines the strength and hardness of chromium with the toughness and impact resistance of nickel. This makes it highly suitable for high-stress components such as crankshafts. The alloy offers excellent resistance to wear and fatigue, which are crucial for crankshaft performance. Option D: Silicon steel This statement is incorrect . Silicon steel is primarily used for electrical applications, such as transformers and electric motor cores. It is not commonly used in motor car crankshafts because it does not provide the necessary strength and toughness required for such mechanical components. Therefore, the correct answer is Option C: Nickel-chrome steel , as it is the most commonly used steel for motor car crankshafts due to its ideal combination of strength, toughness, and resistance to wear.

[#198] Corrosion resistance of steel is increased by addition of
Correct Answer

(A) Chromium and nickel

Explanation

Solution: Nickel (Ni): Nickel is added in large amounts, over about 8%, to high Chromium stainless steels to form the most important class of corrosion and heat resisting steels.

[#199] By severely deforming a metal in a particular direction it becomes
Correct Answer

(D) Anisotropic

Explanation

Solution: Anisotropy, is the property of being directionally dependent, which implies different properties in different directions, as opposed to isotropy.

[#200] Iron-carbon alloys containing carbon ________ 4.3% are known as hyper-eutectic cast irons.
Correct Answer

(C) More than

Explanation

Solution: Iron-carbon alloys containing carbon more than 4.3% are known as hyper-eutectic cast irons. hypereutectic cast iron (>4.3 % C).