This set of Mechanical Behaviour Objective Questions & Answers focuses on “Malleability”.
1. The ability of a material to undergo plastic deformation without rupture, when a compressive force is applied, is known as ______
c) Compressive strength
Explanation: Malleability is defined as the ability of a material to undergo plastic deformation without fracture in compression state. While in the case of ductility tensile Force comes into the picture. Formability of a material is defined as the ability of sheet metal to be formed in a desired shape without fracturing.
2. Which metal has maximum malleability?
Explanation: Gold has maximum malleability. Its one-gram mass can be made into a sheet of a 1-meter square. Platinum, silver and gold have good malleability but less than that of gold.
3. Which metal shows good malleability but poor ductility?
Explanation: Lead shows high plastic deformation under the application of tensile force but not on compression force. Some FCC crystal structure materials show both good malleability and ductility. Examples are silver, gold and aluminium.
4. With an increase in temperature, malleability of material ______
c) Remains constant
d) Varies independent of temperature
Explanation: Materials show good malleability at higher temperatures. It shows the same effect as on ductility. That’s why materials are deformed by hot working.
5. Malleability is the property of a material to be formed into ______
Explanation: Malleability is the ability of material to be formed into sheets. By applying compressive force by forging or hammering, material is made into sheets. While the ability of a material to be drawn into wires is called ductility.
6. Malleable iron is made by heating white iron between _____ for a long time period.
Explanation: Malleable iron is made by heating white iron on temperature 800-900°C. Heating is done for a long time so as to decompose cementite into graphite clusters. This iron has good malleability.
7. Malleable cast iron consists of _____
a) Graphite flakes
b) Graphite nodules
c) Graphite clusters
Explanation: In malleable iron, graphite clusters are present in the ferrite or pearlite matrix. This shape of graphite increases malleability of cast iron. Grey cast iron consists of graphite flakes and nodular cast iron consist graphite nodules.
8. Crystal structure of a material is important factor, which affects the malleability.
Explanation: Crystal structure of material affects the motion of dislocations. In FCC crystal structure dislocations move relatively easily and have high malleability. While in HCP crystals dislocation motion is difficult, so these have less malleability.
9. Which statement is false regarding malleability?
a) Presence of interstitials decreases malleability
b) With an increase in temperature malleability of material decreases
c) FCC crystals generally have good malleability
d) Materials with weak metallic bond tend to have good malleability
Explanation: With an increase in temperature malleability of material increases. At higher temperatures, metal becomes soft and deform easily. Forming of metal becomes easy on high temperatures.
10. Materials with stronger metallic bonds exhibit high malleability.
Explanation: In materials with stronger metallic bonds, extra energy is required to rearrange the atoms for permanent deformation. That’s why their malleability is poor.
Sanfoundry Global Education & Learning Series – Mechanical Behaviour & Testing of Materials.
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