# Mechanical Behaviour Questions and Answers – Formability

This set of Mechanical Behaviour Multiple Choice Questions & Answers (MCQs) focuses on “Formability”.

1. The ability of a metal workpiece to undergo plastic deformation without being damaged is known as ____
a) Formability
b) Stiffness
c) Resilience
d) Yield strength

Explanation: Formability is the ability of a metal to undergo plastic deformation without being damaged. Stiffness is resistance to elastic deflection. Resilience is energy absorbed when the material is deformed elastically.

2. Which instrument is used to measure formability?
a) Universal testing machine
b) Impact testing machine
c) Erichsen machine
d) Fatigue testing machine

Explanation: Erichsen machine is used to measure formability of sheet metal. UTM is used to measure strength. Fatigue testing machine is used to measure fatigue strength and impact testing machine to measure impact strength.

3. What is the reason of orange-peel effect?
a) Coarse grain structure
b) Fine grain structure
c) Inclusions
d) Impurities

Explanation: Grain size greatly affects deep drawing. Coarse grain size gives the rough surface appearance. It is known as orange-peel effect.

4. ______ increases the formability of the metal sheet.
a) Annealing
b) Cold working
c) Inclusions
d) Grain coarsening

Explanation: Annealing causes recrystallization in sheet metal reducing stresses. It hence improves formability. Cold working and inclusions decrease formability.

5. Erichsen value of formability ______ with the thickness of the metal sheet.
a) Increases
b) Decreases
c) Remains constant
d) First increases and then decreases

Explanation: With an increase in thickness of the sheet, the extent to which it can plastically deform increases. Thus the formability increases.

6. Formability of sheet metal ____ with an increase in normal anisotropy.
a) Increases
b) Decreases
c) Remains constant
d) Varies independently

Explanation: With an increase in normal anisotropy, the flow stress of material decreases. Decreased flow stress increases the strength of the cup section. Thus formability increases with normal anisotropy.

7. In the _____ test, the specimen is bent between two rollers until an angle between 30° to 45° is reached.
a) Free bending test
b) Olsen cup test
c) Swift cup test
d) Fukui conical cup test

Explanation: Free bending test is performed by bending the specimen to 30° to 45° angle. Observations are made to see whether cracks are formed. Olsen, Swift and Fukui conical cup tests are performed by measuring cupping value.

8. What is the value of lankford coefficient (r) for good deep drawable material?
a) ≤ 1
b) ≤ 2
c) ≤ 3
d) ≤ 4

Explanation: Lankford coefficient is a specific material property. It is the ratio of width deformation to thickness deformation in a uniaxial tensile test. It should be equal to or below 2 for good deep drawability.

9. Inclusions don’t affect formability of materials.
a) True
b) False

Explanation: Impurities become elongated during rolling. These are known as stringers. These can cause the sheet to fail by cracking.

10. Lack of symmetry in crack shows anisotropy in a material.
a) True
b) False

Explanation: Type of crack formed is used to identify the directional property of a material. Lack of symmetry shows anisotropy. Anisotropy tells the different properties in different directions.

Sanfoundry Global Education & Learning Series – Mechanical Behaviour & Testing of Materials.

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