GATE MT Principles of heat treatment of steels, TTT and CT diagrams; Surface hardening treatments; Recovery, recrystallization and grain growth; Heat treatment of cast iron and aluminium alloys. PYQs & Answers

Questions 1–10 of 10. Imported answers require independent review unless marked reviewed.

The microstructures of a quenched steel tempered at three temperatures

for a fixed time are schematically illustrated. The solid circles represent cementite particles in ferrite matrix;

and

are average radii of cementite particles, and

and

are volume fractions of cementite at temperatures

and

, respectively. If the cementite in steel is more noble than ferrite, then which one of the three microstructures will have the highest corrosion rate when exposed to an aqueous solution of 3.5 wt. % NaCl?

Diagram for Metallurgical Engineering question 42

Your answerChoose one option.

Microstructure at

Independent of microstructure

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For the given schematic TTT diagram of an eutectoid steel, the following statement(s) is/are true for the heat treatment schedules HT-1, HT-2, and HT-3.

Diagram for Metallurgical Engineering question 50

Your answerSelect all correct options. You can choose more than one.

HT-3 leads to the formation of a pearlite microstructure

HT-1 leads to a predominantly martensite microstructure

HT-2 leads to a bainite microstructure

HT-3 leads to a mixture of pearlite and bainite microstructure

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The CCT diagram of a eutectoid steel with a superposed cooling curve is shown in the figure. The microstructure at room temperature (RT) after this heat treatment is ____________

Diagram for Metallurgical Engineering question 22

Your answerChoose one option.

pearlite only

pearlite + retained austenite

martensite only

pearlite + martensite

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Identify the correct statement(s) with respect to the role of nickel as an alloying element in steels.

Your answerSelect all correct options. You can choose more than one.

It increases the M_s temperature

It is an austenite stabiliser

It decreases the M_s temperature

It is a carbide former

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

Your answerChoose one option.

Nickel

Manganese

Carbon

Silicon

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

Your answerChoose one option.

Oil > Water > Brine > Air

Brine > Oil > Water > Air

Brine > Water > Oil > Air

Water > Brine > Oil > Air

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A heavily cold-worked metal will

Your answerChoose one option.

yield a coarser recrystallized grain size.

possess a lower driving force for recrystallization.

have a higher energy barrier for nucleation of recrystallized grains.

recrystallize at lower temperatures.

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In a Jominy end-quench test of the eutectoid plain-carbon steel, which of the following represents the sequence of microstructures observed from the quenched end of the specimen?

Your answerChoose one option.

Fine Pearlite, Coarse Pearlite, Martensite and Pearlite, Martensite

Martensite, Martensite and Pearlite, Fine Pearlite, Coarse Pearlite

Coarse Pearlite, Pearlite and Martensite, Fine Pearlite, Martensite

Martensite, Martensite and Pearlite, Coarse Pearlite, Fine Pearlite

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A steel is plastically worked in the temperature range below the nose of the TTT curve and above M

, followed by quenching to produce fine martensite. What is this process called?

Your answerChoose one option.

Martempering

Ausforming

Inter-critical form

Normalizing

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During heat treatment of a cold worked metal, recrystallization is 20% complete after 100 s. The transformation (in %) in 400 s is ________ (answer up to two decimal places)

(Assume Avrami exponent, n = 2)

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GATE MT Principles of heat treatment of steels, TTT and CT diagrams; Surface hardening treatments; Recovery, recrystallization and grain growth; Heat treatment of cast iron and aluminium alloys. PYQs

How to practice Principles of heat treatment of steels, TTT and CT diagrams; Surface hardening treatments; Recovery, recrystallization and grain growth; Heat treatment of cast iron and aluminium alloys.

Question 42

Question 50

Question 22

Question 31

Question 9

Question 10

Question 20

Question 18

Question 20

Question 49