Strengthening Mechanisms - Mechanical Behaviour of Materials - Metallurgical Engineering Previous Year Questions

1

2007 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2007

Match the terms from group I to their descriptions in group II.

Group I	Group II
(P) Hall-Petch Effect	(1) Solute-dislocation interaction
(Q) Bauschinger Effect	(2) Dislocation multiplication
(R) Cottrell atmosphere	(3) Grain boundary strengthening
	(4) Barrelling under compression
	(5) Mechanical hysteresis during plasticity

A

P-3, Q-5, R-1

B

P-1, Q-4, R-3

C

P-3, Q-1, R-2

D

P-4, Q-3, R-2

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2

2008 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2008

A metal with an average grain size of 36 \(\mu m\) has yield strength of 250 MPa and that with 4 \(\mu m\) has 500 MPa. The friction stress of the metal in MPa is

A

31.2

B

62.5

C

125

D

250

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3

2008 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2008

Identify the attributes associated with dispersion hardened alloys
(P) dispersoids do not dissolve in the matrix even at high temperatures
(Q) dispersoids are coherent with the matrix
(R) dispersoids impart creep resistance to the alloy
(S) dispersoids improve the corrosion resistance of the alloy

A

P, S

B

Q, R

C

Q, S

D

P, R

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4

2009 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2009

During low temperature plastic deformation of an under-aged precipitation hardened alloy, dislocations

A

climb to completely avoid the precipitate

B

loop around the precipitate

C

cross-slip to completely avoid the precipitate

D

cut through the precipitate

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5

2012 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2012

Regarding recrystallization, which one of the following statements is NOT correct?

A

Higher the amount of cold work, lower is the recrystallization temperature

B

Higher the recovery, higher is the recrystallization temperature

C

Higher the temperature of cold work, higher is the recrystallization temperature

D

Finer the initial grain size, higher is the recrystallization temperature

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6

2013 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2013

The yield strength of a polycrystalline metal increases from 100 MPa to 145 MPa on decreasing the grain size from 64 μm to 25 μm. The yield strength of this metal (in MPa) having a grain size of 36 μm is

A

110

B

125

C

140

D

165

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7

2014 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2014

Match the following strengthening methods (Group I) in metallic alloys with typical mechanisms responsible (Group II) for them.

Group I	Group II
P. Grain size strengthening Q. Work hardening R. Dispersion strengthening S. Solid solution hardening	1. Orowan looping 2. Suzuki interaction 3. Lomer-Cottrell barrier 4. Dislocation pileup at grain boundaries

A

P-3, Q-4, R-2, S-1

B

P-3, Q-2, R-1, S-4

C

P-4, Q-3, R-1, S-2

D

P-4, Q-1, R-3, S-2

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8

2017 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2017

Both creep resistance and tensile strength of a metal can be enhanced by

A

increase in the grain size

B

decrease in the grain size

C

addition of dispersoids

D

annealing

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9

2025 · Metallurgical Engineering · Mechanical Behaviour of Materials · Strengthening Mechanisms

Metallurgical Engineering (MT) 2025

Two randomly oriented polycrystalline copper samples with average grain sizes of 10 µm (Sample A) and 100 µm (Sample B) were tested at room temperature.
Given:
\(E_A\) = Young’s modulus of Sample A
\(E_B\) = Young’s modulus of Sample B
\(YS_A\) = Yield strength of Sample A
\(YS_B\) = Yield strength of Sample B
Which one of the following statements is CORRECT?

A

\(E_A > E_B\) and \(YS_A > YS_B\)

B

\(E_A = E_B\) and \(YS_A < YS_B\)

C

\(E_A > E_B\) and \(YS_A = YS_B\)

D

\(E_A = E_B\) and \(YS_A > YS_B\)

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