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4

Sub zero treatment of steel is done to

A. Suppress martensite transformation

B. Enhance its working performance in sub zero atmosphere

C. Reduce the retained austenite in hardened steel

D. Induce temper brittleness after its hardening

Correct Answer :

C. Reduce the retained austenite in hardened steel


Related Questions

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4

The main charge in blast furnace is usually

A. Iron ore & coke

B. Iron ore, coke & air

C. Limestone, coke & iron ore

D. Limestone, sand & iron ore

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4

For an ideal gas, Cp - Cv is

A. R

B. -R

C. 0

D. (3/2) R

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4

The most detrimental impurity in high pressure boiler feed water is

A. Suspended salt

B. Dissolved salt

C. Silica

D. Turbidity

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4

__________ of test specimens is not involved in any hardness testing method.

A. Fracture

B. Indentation

C. Wear

D. Scratch

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4

Triple point of water is

A. 0°F

B. 492°R

C. 0°K

D. -273°C

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4

__________ remains constant during the adiabatic cooling of moist air.

A. Wet bulb temperature

B. Dry bulb temperature

C. Relative humidity

D. Specific humidity

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4

Satellites burn off during re-entry to earth's atmosphere, because of the

A. Combustion with air

B. Gravitational pull by earth

C. Friction with earth's atmosphere

D. Loss in weight of the satellite

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4

Carbide tipped cutting tools are manufactured by powder metallurgy techniques and have a composition of

A. 90% tungsten carbide and 10% cobalt

B. 70% aluminium oxide & 30% silica

C. 30% nickel, 15% chromium & 55% tungsten

D. 65% tungsten & 35% zirconium

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4

The __________ of a double acting reciprocating pump as compared to the single acting pump will be almost double.

A. Flow output

B. Head developed

C. Overall efficiency

D. Weight

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4

Which of the following phenomenon/ phenomena is/are diffusion controlled?

A. Dislocation climb

B. Cross-slip

C. Twinning

D. Recrystallisation

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4

Consider an ideal solution of components A and B. The entropy of mixing per mole of an alloy containing 50% B is

A. R ln 2

B. -R ln 2

C. 3 R ln 2

D. -3R ln 2

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4

Catalyst used in the 'catalytic converter' employed in automobile exhaust line for complete combustion/oxidation of carbon monoxide, nitrogen oxides and hydrocarbons is

A. Alumina

B. Platinum

C. Vanadium pentoxide

D. Iron oxide

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4

Volumetric composition of flue gas analysed with the Orsat apparatus is : CO2 = 12%, O2 = 8%, CO = nil, N2 = 80%. This flue gas composition indicates that

A. Pure oxygen has been used for combustion

B. Nitrogen percentage in the fuel is very high

C. Excess air has been used for combustion

D. Hydrogen is not present in the fuel

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4

Change in volume of metals from absolute zero temperature to their melting points is

A. Almost same for all metals

B. Different for different metals

C. Less for low melting point metals

D. Less for high melting point metals

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4

Which of the following is prone to cup and cone fracture?

A. Cast iron

B. Soft brass

C. Round specimen of ductile metal

D. Flat tensile specimen of ductile metal

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4

What is the range of tempering temperature (°C) for most of the materials?

A. 75-100

B. 200-300

C. 350-450

D. 500-600

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4

Maximum hardenability of steel depends upon its

A. Chemical composition

B. Carbon content

C. Grain size

D. Alloying elements content

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4

Which of the following is preferred for riveting?

A. Lap joint

B. Butt joint

C. Either (A) or (B)

D. Neither (A) nor (B)

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4

Out of the following substances, one ton of __________ will store the maximum heat for a rise of 30°C in temperature.

A. Steel

B. Lignite

C. Water

D. Lime stone

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4

Lead is added to 60:40 brass primarily to improve

A. Machinability

B. Corrosion resistance

C. Fluidity

D. Strength

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4

Steel rods are normally used for concrete reinforcement because concrete and steel have almost equal

A. Tensile strength

B. Compressive strength

C. Young's modulus

D. Thermal co-efficient of expansion

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4

In a forced draft cooling tower, water is cooled from 95 to 80°F by exposure to air with a wet bulb temperature of 70°F. In this case, the

A. Range is 15°F

B. Approach is 10°F

C. Both (A) & (B)

D. Neither (A) nor (B)

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4

The transition temperature at which all the ferromagnetic materials become paramagnetic materials is termed as the 'Curie temperature'. Its value for cobalt is __________ °C.

A. 768

B. 1127

C. 1359

D. 1480

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4

The most important consideration, while designing the refrigeration system of an aircraft is that the refrigeration system

A. Is as light as possible

B. Has very high C.O.P.

C. Employs minimum quantity of refrigerant

D. Consumer minimum horse power

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4

Half life of a radioactive isotope corresponds to the time required for half of the __________ to decay.

A. Atoms

B. Neutrons

C. Nucleons

D. Electrons

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4

Velocity of a gas in sound is not proportional to (where, T = Absolute temperature of the gas. P = Absolute pressure of the gas. y = Ratio of specific heats (Cp/Cv) ρ = specific weight of the gas)

A. √T

B. 1/√P

C. √y

D. 1/√ρ

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4

Pick out the wrong statement.

A. A ferromagnetic material becomes paramagnetic above the 'Curie temperature'

B. Permanent magnets are made of hard materials, whereas electromagnets require soft magnetic materials

C. Soft magnetic materials (e.g., pure iron) have higher permeability and low hysterisis loss and coercive forces

D. Tungsten steel and alnico are not hard magnetic materials

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4

Corrosion is

A. A physical phenomenon

B. A chemical phenomenon

C. Same as erosion

D. An uncontrollable phenomenon

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4

Which of the following is the largest quantum of pressure?

A. 1 kg/cm2

B. 1 bar

C. 1 atmosphere

D. 1 kilo Pascal

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4

__________ furnace is generally used in the non-ferrous foundries.

A. Direct arc

B. Indirect arc

C. Resistance

D. Induction