Engineering Materials MCQ Questions & Answers | Mechanical Engineering

Mild steel has maximum ductility.
Those materials show the lower amount of the carbon.
Alloying elements from one metal to another metal.
Some materials can have the inherent ability to withstand when the tensile load has been applied pave of the materials like low carbon steels and medium carbon steel shows somehow desirables properties like ductility.

hot hardness or red hardness corresponds to hardness of a material at high temperatures.
As the temperature of material increases, hardness decreases and at some point a drastic change in hardness occurs

Point defects are where an atom is missing or is in an irregular place in the lattice structure.
Point defects include self interstitial atoms, interstitial impurity atoms, substitutional atoms and vacancies

The most common usage of nichrome is as resistance wire, although they are also used in some dental restorations (fillings) and in a few other applications

The Strength of the material is defined as the quality or state of being physically strong, the capacity of an object or substance to withstand great force or pressure

Stiffness is defined as the property of a material which is rigid and difficult to bend.
The example of stiffness is rubber band

Pearlite is a Mixture of Ferrite and Cementite (alternately arranged as like pearls)
obtain 100% pearlite at 727 deg.C.
Soft Phase than Austenite but posses better strength than Ferrite.

Delta iron occurs at temperture in between 1400°C and 1539°C

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

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.