This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Mechanical Properties”.
1. The tendency of a deformed solid to regain its actual proportions instantly upon unloading known as ______________
a) Perfectly elastic
b) Delayed elasticity
c) Inelastic effect
Explanation: If the recovery of the solid is instantaneous and complete, it is known as perfectly elastic. Delayed elasticity is defined as the steady mode of solid recuperation, while the inelastic effect is when the recuperation of deformed solid is partial. Plasticity is the contradictory occurrence of elasticity.
Explanation: The ratio of load to the area is the description of stress on the solid. The ratio of alteration in length to its original length is the description of strain on the solid. Young’s modulus of elasticity is defined as the ratio of stress on the solid to the strain of the solid The ratio of the mass of the solid to its volume is defined as density.
3. The permanent mode of deformation of a material known as _____________
c) Slip deformation
d) Twinning deformation
Explanation: Plasticity is defined as the property of a material due to which it is permanently deformed due to loading. Elasticity is the temporary form of deformation. Twinning and Slip are mechanisms of Plastic deformation.
4. The ability of materials to develop a characteristic behavior under repeated loading known as ___________
Explanation: Toughness is the ability of a material to absorb energy during deformation, while resilience is its capacity to absorb the energy. Hardness is the knack of material to defy indentation. The ability of a material to develop a characteristic behavior under repeated loading is known as fatigue.
Explanation: Tensile strength is defined as the ratio of maximum load (kg) applied to its cross-sectional area (cm2). Young’s modulus of elasticity is defined as the ratio of stress on the solid to the strain of the solid. The remaining choices given are reciprocals of same.
6. Which of the following factors affect the mechanical properties of a material under applied loads?
a) Content of alloys
b) Grain size
c) Imperfection and defects
d) Shape of material
Explanation: Contents of alloys improve or decrease the hardness and strength of materials. Finer grain sizes improve the strength of the material. Imperfection and defects reduce the strength of the material. Shape, however, has little or no effect on the material.
7. The ability of a material to resist plastic deformation known as _____________
a) Tensile strength
b) Yield strength
c) Modulus of elasticity
d) Impact strength
Explanation: The point of stretching where it increases suddenly is known as yield strength, i.e. the region where the stretch is elastic. Tensile strength is the force needed to fracture the material. Impact strength is the capacity of a material to resist shock energy before a fracture.
8. The ability of a material to be formed by hammering or rolling is known as _________
Explanation: The capacity of a material to withstand deformation under compression, i.e. hammering is known as malleability. The capacity of a material to withstand deformation under tension, i.e. wire drawing is known as ductility. Hardness is the knack of a material to oppose indentation. Brittleness is the tendency to fracture without deformation of the material.
9. What type of wear occurs due to an interaction of surfaces due to adhesion of the metals?
a) Adhesive wear
b) Abrasive wear
c) Fretting wear
d) Erosive wear
Explanation: Adhesive wear occurs due to frictional contact between metals. Abrasive wear occurs due to the descending of the surface of the material over a different harder surface. Fretting wear is the wear which causes the deduction of material from both the surfaces in contact over an extended period of time. Erosive wear causes wear of the material due to the effect of solid or liquid particles over a short period of time.
10. Deformation that occurs due to stress over a period of time is known as ____________
a) Wear resistance
Explanation: Creep is the time-dependent deformation of the material under stress. Wear resistance, fatigue, and fracture deal with deformation under stress without a time factor, i.e. they are time-independent.
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