GATE MT topic:materials-science PYQs & Answers — Page 32

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topic:materials-science

Questions 311–320 of 650. Imported answers require independent review unless marked reviewed.

Topic practice 650 questionsPage 32 of 65

Molten steel at 1873 K weighing 100 metric tons is desulfurized using 1250 kg of synthetic slag by equilibration. If the sulfur content in the steel is reduced from 0.015 mass% to 0.0025 mass%, the desulfurizing index is ______ (round off to the nearest integer).

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High cycle fatigue data for an alloy at various alternating stresses,

(see figure) is given below.

Stress, (MPa)	, Number of cycles to failure
500	1000
400	10000
300	100000
200	1000000

A specimen of this alloy is subjected to multiple stress cycles sequentially in the following order: (i) first 5000 cycles at

MPa followed by (ii) 25000 cycles at

MPa and finally (iii) at

MPa. Assuming that Miner’s law is obeyed, the number of cycles to failure at the final applied stress of 500 MPa is __________.

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The partial molar enthalpy of Au in an Ag-Au melt containing 25 mol% Au at 1400 K is −8300 J·mol⁻¹. Assuming regular solution behavior, the activity of Au in the melt is ______ (round off to 3 decimal places).

Given:

J·K⁻¹·mol⁻¹

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A rectangular block made of Material I and Material II of identical cross sections (as shown in the figure) has a temperature (T) of 435 K and 400 K at the bottom and top surfaces, respectively. Assuming purely steady state conductive heat transfer, the temperature at the interface is ______ K (round off to nearest integer).

(Given: The two parts of the block made of Material I and Material II have equal thickness of 25 mm each. The thermal conductivities of Material I and Material II are 50 W·m⁻¹·K⁻¹ and 200 W·m⁻¹·K⁻¹, respectively.)

Diagram for Metallurgical Engineering question 54

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During solidification of a pure metal, the radius of critical nucleus at an undercooling of 10 K is __________ ×

m (answer rounded off to 1 decimal place).

Given: solid/liquid interface energy = 0.177 J·m⁻²,

melting point of the metal = 1356 K and

latent heat of fusion = 1.88 ×

J·m⁻³

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The concentration

of a solute (in units of atoms·mm⁻³) in a solid along

direction (for

) follows the expression

where

is in mm,

and

are in units of atoms·mm⁻⁵ and atoms·mm⁻⁴, respectively. Assuming

, the magnitude of flux at

mm is _____ ×

atoms·mm⁻²·s⁻¹ (answer rounded off to the nearest integer).

Given: diffusion coefficient of the solute in the solid is 3 ×

mm²·s⁻¹.

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Assuming that Dulong-Petit law is valid for a monoatomic solid, the ratio of heat capacities

at 500 K is ______ (round off to 3 decimals).

Given: molar volume = 7×10⁻⁶ m³·mol⁻¹,

isothermal compressibility = 8×10⁻¹² Pa⁻¹,

isobaric expansivity = 6×10⁻⁵ K⁻¹ and

J·K⁻¹·mol⁻¹.

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A sieve made of steel wire of diameter 53 μm has an aperture size of 74 μm. Its mesh number is ______ (round off to the nearest integer).

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Steel plates are welded autogenously using Gas Tungsten Arc welding with an arc heat transfer efficiency of 0.65. The first weld is made using a welding current of 200 A at an arc voltage of 18 V with a welding speed of 0.002 m·s⁻¹. The second weld is made at a welding speed of 0.002 m·s⁻¹ with the same arc voltage. If both the welds have identical heat input, the welding current of the second weld is ________ A (round off to the nearest integer).

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A cylindrical specimen of an Al alloy with diameter of 30 mm is cold extruded to a diameter of 20 mm. If the flow behavior of the alloy is expressed by the equation,

MPa, the ideal plastic work of deformation per unit volume is ________ ×

J (answer rounded off to the nearest integer).

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GATE MT topic:materials-science PYQs

Question 51

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Question 54

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Question 58

Question 59

Question 60