This set of Mechanical Behaviour Multiple Choice Questions & Answers (MCQs) focuses on “Tensile Strength”.
1. What is tensile strength of brass?
a) 550 MPa
b) 220 MPa
c) 350 MPa
d) 760 MPa
View Answer
Explanation: Tensile strength of brass is 550 MPa. 220 MPa is UTS (ultimate tensile strength) for 99.9% copper. 350 MPa is UTS for cupronickel (10% Ni) and 760 MPa is UTS for high strength alloy steel.
2. Match the following?
| Material | Tensile strength (in MPa) |
|---|---|
| i) Annealed silver | p) 15 |
| ii) Rubber | q) 33 | iii) Brass | r) 170 |
| iv) Glass | s) 550 |
a) i-q, ii-p, iii-r, iv-s
b) i-r, ii-p, iii-s, iv-q
c) i-p, ii-r, iii-q, iv-s
d) i-r, ii-p, iii-q, iv-s
View Answer
Explanation: Annealed silver has UTS 170 MPa. Rubber has very low tensile strength (15 MPa). Brass has high UTS 550 MPa and glass has UTS 33 MPa.
3. Which one of the following, is not a unit of ultimate tensile strength?
a) MPa
b) N/m2
c) Kg/m3
d) psi
View Answer
Explanation: UTS is the maximum stress a material can withstand before fracturing. UTS have units of stress, which is force acting per unit area. Thus MPa, N/m2 and psi are units for ultimate tensile strength.
4. The ability of the material to withstand tensile force, without breaking, is known as ______
a) Yield strength
b) Tensile strength
c) Compressive strength
d) Creep strength
View Answer
Explanation: The ability of the material to withstand uniaxial tensile force is known as tensile strength. While the minimum applied stress, which causes permanent deformation, is yield strength. Ability to withstand compressive force without breaking is the compressive strength.
5. With an increase in the degree of cold working, tensile strength of material ______
a) Increases
b) Decreases
c) Remains constant
d) First decreases then increase
View Answer
Explanation: As the percent of cold working increases, UTS of materials increases. It is due to an increase in dislocation density and their interaction with imperfections. Cold working is therefore an effective strengthening mechanism for single phase materials.
6. Which one of the following factor decreases the tensile strength?
a) Cold working
b) Alloying
c) Temperature rise
d) Grain refinement
View Answer
Explanation: With an increase in temperature, UTS of material decreases. The reason is softning of material which leads to easy movement of dislocations. On other hands, cold working, alloying and grain refinement increases UTS by producing strains in a material.
7. Which statement is false?
a) With an increase in the degree of cold working, UTS increases.
b) UTS increases with a decrease in temperature.
c) UPS increases with an increase in grain size.
d) Larger the difference between the radius of solute and solvent atoms of alloy, higher is the tensile strength.
View Answer
Explanation: As grain size of the material decreases, UTS increases. It is due to the presence of more grain boundary area, which checks the motion of dislocations. Thus more energy is required to deform the material.
8. Tensile strength is used as a design criterion for ductile materials.
a) True
b) False
View Answer
Explanation: Tensile strength is used as a design criterion for brittle materials. While yield strength is used as design criterion for ductile materials. Because in ductile materials, considerable plastic deformation takes place before UTS which is undesirable.
9. If the Brinell hardness of a steel specimen is measured 149 HBN. What will be the UTS?
a) 431 MPa
b) 514 MPa
c) 608 MPa
d) 637 MPa
View Answer
Explanation: TS = 3.45 × HBN
TS = 3.45 × 149
= 514.05
~ 514 MPa
Here, HBN = Brinell hardness, TS = tensile strength of material in MPa.
10. Brinell hardness of a steel specimen is 151 HBN. Give the value of UTS of Steel in psi.
a) 520 psi
b) 42050 psi
c) 75500 psi
d) 86200 psi
View Answer
Explanation: TS = 500×HBN
TS = 500 × 151
= 75500 psi
Here, HBN = Brinell hardness, TS = tensile strength of material in psi.
11. Find the minimum tensile strength of spring material ASTM A232 having diameter 3 millimeter, exponent m = 0.155 and constant A = 173 kpsi.
a) 120 kpsi
b) 146 kpsi
c) 158 kpsi
d) 167 kpsi
View Answer
Explanation: Tensile strength of spring material is given by following formula TS = A/dm
= 173/30.155
= 145.91
~ 146 kpsi Here, A = material constant in kpsi, d = diameter in mm, m = exponent value, TS = tensile strength of material in kpsi.
12. Tensile strength depends on the molecular structure of the material.
a) True
b) False
View Answer
Explanation: Molecular structure of materials is responsible for interatomic bonding of atoms inside the material. As molecular structure of material changes, the bonding also changes. Thus required energy to break these bonds greatly changes.
13. Tensile strength increases with increasing ______
a) Temperature
b) Molecular weight
c) Purity
d) Grain size
View Answer
Explanation: Tensile strength increases with the molecular weight of material. It is due to the effect of entanglement. Other factors temperature, purity and grain size, on increasing, cause in decreasing UTS.
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