Question 1

Heat treatment for softening hardened steel  Which heat treatment process is primarily used to soften hardened steel and refine its structure for machining/formability? Choose the correct option.

Accepted Answer

Concept Annealing involves heating to a suitable temperature, holding, and cooling slowly (usually in the furnace) to soften the steel, increase ductility, and relieve stresses. Tempering reduces brittleness of quenched steel but does not fully soften it; carburising adds carbon; normalising air-cools and yields higher hardness than full anneal. Final Answer Annealing

Question 2

Lower critical temperature (A₁) of steel vs. carbon content  How does the lower critical temperature (A₁) behave for plain carbon steels as carbon content varies? Choose the correct option.

Accepted Answer

Concept The lower critical temperature (A₁) for plain carbon steels is taken as approximately 723–727°C and is commonly treated as essentially constant for these steels in basic metallurgy problems. The upper critical temperature (A₃) decreases with increasing carbon. While Ac₁/Ar₁ can vary slightly with heating/cooling rates, the standard teaching is that A₁ is effectively the same for plain carbon steels. Final Answer Is the same for all steels

Question 3

Comparative ductility among common engineering metals  Among the following, which material typically exhibits the greatest ductility at room temperature? Choose the correct option.

Accepted Answer

Concept Room-temperature ductility (elongation/reduction of area) is very high for copper; it is one of the most ductile common metals (exceeded mainly by noble metals like gold/silver). Mild steel, nickel, and aluminium are ductile as well, but copper generally shows the highest ductility among the listed options. Final Answer Copper

Question 4

Carbon content range for cast irons  Select the correct typical carbon range that defines cast iron (as opposed to steel). Choose the correct option.

Accepted Answer

Concept Cast iron is generally defined for carbon contents from about 2% up to roughly 4.3–4.5%. Many curricula round the lower bound to 1.7% (the eutectoid limit of steel) to distinguish it clearly from steels. Final Answer 1.7 to 4.5% C

Question 5

Full annealing practice for hypo-eutectoid steel  In full annealing of a hypo-eutectoid steel, the steel is heated to 30–50°C above the upper critical temperature and then cooled how? Choose the correct option.

Accepted Answer

Concept Full annealing of hypo-eutectoid steels: heat to about 30–50°C above A₃ to form homogeneous austenite and cool slowly in the furnace. This promotes full transformation to coarse pearlite/ferrite and produces maximum softness and ductility. Final Answer Slowly in the furnace (furnace cooling)

Question 6

Effect of small boron additions to steel  A small percentage of boron is added to steels primarily to achieve which effect? Choose the correct option.

Accepted Answer

Concept Minute additions of boron (on the order of tens of ppm) markedly increase hardenability by reducing the tendency for ferrite/pearlite to form at prior austenite grain boundaries, allowing deeper martensitic transformation on quenching. Final Answer Increase hardenability

Question 7

Classification of cast irons by carbon content  Iron–carbon alloys containing 1.7 to 4.3% carbon are classified as which type of cast iron with respect to the eutectic composition (≈4.3% C)? Choose the correct option.

Accepted Answer

Concept The eutectic composition for Fe–C cast irons is about 4.3% C. Cast irons with less than this value (≈2.0–4.3% C; many texts start at ≈1.7%) are termed hypo-eutectic. Those with carbon content greater than 4.3% are hyper-eutectic. Final Answer Hypo-eutectic cast irons

Question 8

Heat treatment sequence: Arrange the metallurgical phenomena in correct chronological order for annealing of cold-worked steels.  As temperature/time increases during a standard annealing heat cycle, the microstructural stages occur in a characteris…

Accepted Answer

Concept/Approach During annealing of cold-worked steels, three phenomena occur in order: (1) stress relief (recovery), (2) recrystallisation, (3) grain growth. Why this order? • Stress relief / recovery: dislocation rearrangement lowers residual stresses without new grains forming.• Recrystallisation: new, strain-free grains nucleate and grow, replacing the deformed structure.• Grain growth: existing recrystallised grains coarsen when held longer/hotter. Common pitfalls Confusing recovery with recrystallisation, or assuming grain growth can precede recrystallisation. Final Answer Stress relief → recrystallisation → grain growth

Question 9

Cast iron heat treatment: Identify how malleable cast iron is produced.  Manufacturing route selection for obtaining malleable (toughened) cast iron from a base iron.  Choose the correct process description.

Accepted Answer

Concept Malleable cast iron is obtained by heat treating white cast iron for long durations (annealing), transforming cementite into temper carbon and producing a tougher, malleable structure. Why not the others? • Magnesium addition produces ductile (nodular) iron, not malleable iron.• Quick chilling makes white iron, not malleable iron. Final Answer From white cast iron by prolonged annealing (heat treatment)

Question 10

Material property for shock-resisting steels: Identify the most critical requirement.  Design focus: Select the dominant mechanical property needed when steels must withstand sudden impacts and shocks.  Choose the correct property.

Accepted Answer

Concept Shock-resisting steels must absorb impact energy without brittle fracture. The governing property is toughness (high area under the stress-strain curve in the plastic region). Common pitfall Confusing hardness or tensile strength with toughness. High hardness may increase brittleness, which is undesirable under shock loading. Final Answer High toughness

Question 11

The hardness of steel depends upon the

Accepted Answer

amount of carbon it contains

Question 12

When a low carbon steel is heated upto upper critical temperature

Accepted Answer

the average grain size is a minimum

Question 13

Which of the following statement is correct?

Accepted Answer

The chilled cast iron has no graphite.

Question 14

Which of the following statements are true for annealing of steels?

Accepted Answer

all of these

Question 15

Which of the following statement is true about brittle fracture?

Accepted Answer

Many metals with hexagonal close packed (H.C.P) crystal structure commonly show brittle fracture

Question 16

Beryllium bronze has

Accepted Answer

both (a) and (b)

Question 17

Martensite has needle like structure and is magnetic.

Accepted Answer

Correct

Question 18

Which of the following material has nearly zero coefficient of expansion?

Accepted Answer

Invar

Question 19

The iron ore in the charge of blast furnace acts as an iron bearing mineral.

Accepted Answer

True

Question 20

Which of the following display properties similar to that of steel?

Accepted Answer

both (a) and (b)

Engineering Materials Questions