Match the phases of steel in
Group I with the crystal structures in
Group II .
Group I Group II
P. Martensite
1. bcc
Q. Cementite
2. fcc
R. Austenite
3. bct
S. Ferrite
4. Orthorhombic
A. P-3, Q-4, R-1, S-2
B. P-2, Q-3, R-1, S-4
C. P-3, Q-4, R-2, S-1
D. P-4, Q-3, R-2, S-1
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When the radius of tiny particle is less than critical nucleous size then it is called
A. embryo
B. Nuclei
C. embryo and Nuclei
D. growth
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Movement of jogs can produce
A. vacancies
B. interstitial
C. grain boundary sliding
D. grain boundary migration
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Four eutectoid steel samples W, X, Y and Z are austenitized and then subjected to normalising, quenching, martempering and austempering treatments respectively. Which of the following statements is not correct?
A. The microstructure of sample W will be fully pearlitic
B. The microstructure of sample X will be untempered martensite
C. The microstructure of sample Y will be teinpered martensite
D. The microstructure of sample Z will be bainitic
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Secondary hardening in steels arises out of the
A. precipitation of fine alloy carbides at high temperature
B. refinement of ferrite grain size by working
C. decomposition of retained austenite upon heat treatment
D. precipitation of complex inter-metallics upon heat treatment
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Match the materials in
Group 1 with the possible microstructure adjacent to the fusion line in the heat affected zone, in
Group 2 .
Group 1 Group 2
P. Pure aluminium
1. Martensite
Q. 0.6 mass% carbon steel
2. Grain boundary precipitation
R. Aged AI 4.5 mass% Cu alloy
3. Coarse precipitates
S. 18/8 stainless steel
4. Bainite
5. Coherent precipitates
6. Twins
7. Grain growth
A. P-6, Q-1, R-5, S-2
B. P-7, Q-1, R-2, S-4
C. P-4, Q-3, R-2, S-6
D. P-7, Q-1, R-3, S-2
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Tetragonal crystal structure has
A. a = b = c and α = β = γ = 90°
B. a = b ≠ c and α = β = γ = 90°
C. a ≠ b ≠ c and α = β = γ = 90°
D. a = b = c and α = β = γ ≠ 90°
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The percentage of pearlite in 0.8% carbon steel
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Eutectic AI-Sialloys can be modified by small additions of
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A peritectic reaction is
A. α + β ⟶ γ
B. L + α ⟶ β
C. L1 + L2 ⟶ β
D. L + α + β ⟶ γ
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The yield point phenomenon observed in annealed low carbon steel is due to the presence of the following element.
A. silicon
B. carbon
C. phosphorous
D. chromium
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Assertion 'a': Hardenability of steel can be increased by adding certain alloying elements.Reason 'r': The alloying elements can provide a fine dispersion of alloy carbides
A. Both 'a' and 'r' are true, but 'r' is not a correct reason for 'a'
B. Both 'a' and 'r' are false
C. 'a' is true but 'r' is false
D. Both 'a' and 'r' are true and 'r' is a correct reason for 'a'
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A copper sample has been metallographically analysed for determining its mean grain size. It is found to have an ASTM grain size number of 5. The number of grains per mm2 in the sample will be
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The energetic driving force for grain growth is due to
A. dislocations in the matrix
B. grain boundary energy
C. residual strains in different grains
D. stacking fault energy
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Match the following fracture surface features listed in
Group I with the fracture mechanisms listed in
Group II .
Group I Group II
P. Striations
1. Intergranular fracture
Q. Dimples and microvoids
2. Cleavage fracture
R. Flat facets and "river markings"
3. Ductile fracture
S. Jagged surface with grain-like features
4. Fatigue fracture
A. P-1, Q-2, R-3, S-4
B. P-1, Q-3, R-2, S-4
C. P-4, Q-3, R-2, S-1
D. P-2, Q-1, R-4, S-3
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According to Hume Rothery's rules, size of atoms must not differ by more than
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in a typical Ellingham diagram for the oxides, the C + O2 = CO2 line is nearly horizontal because
A. The slope of the line is equal to the enthalpy change at standard state, which is approximately zero is this case
B. The slope of the line is equal to the entropy change at standard state, which is approximately zero in the case
C. CO2 shows non-ideal behaviour
D. CO2 is a gaseous oxide
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Match the following.
Group-I Group-II
P. Hot shortness
1. Overcome by adding excessive amount of manganese
Q. Cold shortness
2. Weld decay
R. Season cracking
3. Reduction in impact strength at low temperatures
S. Sensitization
4. Tendency of brasses to corrode due to high residual stress
A. P-1, Q-3, R-4, S-2
B. P-4, Q-3, R-2, S-1
C. P-1, Q-3, R-2, S-4
D. P-1, Q-2, R-3, S-4
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Hardenability of steel does not depend upon the
A. alloy content
B. grain size
C. amount of carbon present
D. amount of cold work
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The interlamellar spacing, S, and the undercooling, ΔT below the eutectoid temperature in plane carbon steels are related as
A. SαΔT
B. SαΔT2
C. SαΔT-1
D. S α Δ T − 2 1
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