Metallurgical Engineering Gate Yearwise 



Metallurgical Engineering Gate 2021 Questions with Answer

Ques 27 GATE 2021

A hypothetical binary eutectic phase diagram of A-B is shown below. An alloy with 5 wt.% B solidifies with no convection. Assuming steady state, the critical temperature gradient (in K mm-1) required to maintain planar solidification front is: _______ (round off to nearest integer).

Given: Diffusivity of B in liquid = 10-9 m2 s-1 Velocity of solidification front = 4 µm s-1


(100) is the correct answer.

Ques 28 GATE 2021

A thick steel plate containing 0.1 wt.% C is carburized at 950oC. The plate's surface carbon concentration is maintained at 1.1 wt.% C. After 9 hours, the depth (in mm) below the surface at which the carbon concentration is 0.6 wt.% C will be: _______ (round off to 2 decimal places).
Given: Diffusivity of carbon in γ-Fe at 950oC = 1.6 x 10-11 m2 s-1 Error function table:


(0.65) is the correct answer.

Ques 29 GATE 2021

The radius of an interstitial atom which just fits (without distorting the structure) inside an octahedral void of a bcc-iron crystal (in nm) is: _______ (round off to 3 decimal places). Assume the radius of Fe atom to be 0.124 nm.


(0.021) is the correct answer.

Ques 30 GATE 2021

For uniaxial tensile stress-strain behaviour of polycrystalline aluminium, which one of the following statements is FALSE?

A

True stress is always higher than the engineering stress.

B

At the ultimate tensile stress point on the true stress-strain curve, dσ/dε = 0

C

Resilience is the area under the elastic region of the engineering stress-strain curve.

D

Maximum true stress does not correspond to the maximum load.


(b) is the correct answer.

Ques 31 GATE 2021

Which one of the following is FALSE for creep deformation?

A

The minimum creep rate is obtained in the primary stage (stage I).

B

Creep resistance decreases with decrease in grain size.

C

Coble creep occurs via grain boundary diffusion.

D

Nabarro-Herring creep occurs via lattice diffusion.


(a) is the correct answer.

Ques 32 GATE 2021

Which one of the following elements alloyed with iron is a ferrite stabilizer?

A

Nickel

B

Manganese

C

Carbon

D

Silicon


(d) is the correct answer.

Ques 33 GATE 2021

Which one of the following is the correct decreasing sequence of Quenching Power for quenchants used in heat treatment of steels?

A

Oil > Water > Brine > Air

B

Brine > Oil > Water > Air

C

Brine > Water > Oil > Air

D

Water > Brine > Oil > Air


(c) is the correct answer.

Ques 34 GATE 2021

A body is subjected to a state of stress given by the following stress tensor:

If yielding is predicted by the Tresca Criterion, the uniaxial tensile yield stress (in MPa) of the body should be less than or equal to: _______ (round off to nearest integer).


(150) is the correct answer.

Ques 35 GATE 2021

Consider homogeneous nucleation of a spherical solid in liquid. For a given undercooling, if surface energy of a nucleus increases by 20%, the corresponding increase (in percent) in the critical radius of the nucleus is: _______ (round off to nearest integer).


(20) is the correct answer.

Ques 36 GATE 2021

If saturation magnetization of iron at room temperature is 1700 kA m-1 the magnetic moment (in A m2) per iron atom in the crystal is: _______ x10-23 (round off to 1 decimal place). (Given: Lattice parameter of iron at room temperature = 0.287 nm)


(2.0) is the correct answer.

Ques 37 GATE 2021

In the X-ray diffraction pattern of a FCC crystal, the first reflection occurs at a Bragg angle (θ) of 30o. The Bragg angle (in degree) for the second reflection will be: _______ (round off to 1 decimal place).


(35.3) is the correct answer.

Ques 38 GATE 2021

A 0.6 wt.% C steel sample is slowly cooled from 900oC to room temperature. The fraction of proeutectoid ferrite in the microstructure is: _______ (round off to 2 decimal places). Given: Eutectoid composition: 0.8 wt.% C Maximum solubility of carbon in α-Fe: 0.025 wt.% C


(0.25) is the correct answer.

Ques 39 GATE 2021

If the degree of polymerization of polyethylene is 30000, the average molecular weight (in g mol-1) is: _______ (round off to nearest integer). (Given: Atomic weights of carbon and hydrogen are 12 and 1, respectively)


(840000) is the correct answer.

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