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Maximum change in the hardness of martensite occurs in the carbon content range of __________ percent in steel.

A. 0.01 to 0.10

B. 0.2 to 0.4

C. 0.5 to 0.7

D. 0.8 to 1.0

Correct Answer :

B. 0.2 to 0.4


Related Questions

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The temperature at which ferromagnetic material can no longer be magnetised by the outside forces, is termed as the

A. Critical point

B. Curie temperature

C. Inversion temperature

D. Eutectic temperature

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Steel containing low percentage of nickel, chromium & tungsten are termed as the __________ steel.

A. Wrought

B. Tool

C. Alloy

D. Plain carbon

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An alloy of Fe - 0.4 % C is

A. Cast iron

B. Hypo-eutectoid steel

C. Hyper-eutectoid steel

D. Eutectoid steel

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What is the value of included angle of a triangular notch for maximum discharge?

A. 30°

B. 60°

C. 90°

D. 120°

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Solidification time of a molten metal in a casting is proportional to (where, V = volume of metal & A = its surface area; in the casting)

A. V/A

B. V/A2

C. V2/A

D. V2/A2

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Oxygen cylinders used for autogenous (cutting/welding) purposes are

A. Seamless & made of steel

B. Heat treated before use

C. Made by sand casting

D. Welded steel cylinders

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Normalising does not __________ of a metal.

A. Improve machinability & tensile strength

B. Remove internal stresses

C. Refine the structure

D. Remove strains caused by cold working

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Most of the phosphorous present in the blast furnace burden enters into

A. Hot metal

B. Flue gases

C. Slag

D. Refractory lining

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What happens, when SO2 is passed through a solution of H2S in water?

A. Precipitation of sulphur takes place

B. H2SO3 is formed

C. Oleum is formed

D. None of these

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Limestone addition in the blast furnace is done to flux __________ present in the raw materials.

A. SiO2

B. Al2O3

C. MnO2

D. P

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Routing in production, planning & control is concerned with the

A. Sequence of operation to be performed

B. Progress of work performed

C. Authorisation of work to be performed

D. Balancing of load on machines

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Addition of silicon to cast iron

A. Promotes graphite module formation

B. Improves its ductility

C. Does not promote graphite flakes formation

D. Increases the fluidity of molten metal

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More than 95% of __________ is present in corundum.

A. SiO2

B. Al2O3

C. CaSiO2

D. MgO

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The escape velocity of a body on earth which is independent of its mass is about __________ km/second.

A. 3

B. 7

C. 11

D. 15

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Silicon percentage in silicon steel used for electrical equipments is about

A. 1

B. 4.0

C. 8

D. 14

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Insulation of liquid surface can be achieved by __________ on top of its surface.

A. Floating hollow polypropylene spheres

B. Spraying alumina powder

C. Putting cement

D. None of these

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Which of the following performance characteristics of a S.I engine is not affected by the front end volatility of the petrol used?

A. Vapour locking

B. Hot starting

C. Spark plug fouling

D. All 'a', 'b' & 'c'

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4

At absolute zero temperature, for any reaction involving condensed phases

A. Δ G° = 0 , Δ H° = 0

B. Δ H° = 0 , Δ S° = 0

C. Δ S° = 0 , Δ E° = 0

D. Δ S° = 0 , Δ Cp° = 0

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Steam condenser tubes are made of admiralty brass, in which percentage of zinc & copper are __________ respectively.

A. 70 & 30

B. 30 & 70

C. 50 & 50

D. 90 & 10

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4

In the acid Bessemer process, the hot metal should have the following composition.

A. S < 0.05% and P < 0.05%

B. S < 0.05% and P < 1.5%

C. S < 0.05% and P > 1.5%

D. S > 1.5% and P < 0.05%

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High speed steel tools retain their hardness upto a temperature of __________ °C.

A. 500

B. 750

C. 900

D. 1100

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A solid aluminium ball, when quenched in a water bath maintained at 40°C, cools down from 550°C to 450°C in 20 seconds. The expected temperature of the ball after next 20 seconds may be about __________ °C.

A. 370

B. 340

C. 320

D. 300

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__________ stress cannot be sustained by a fluid in equilibrium.

A. Shear

B. Tensile

C. Compressive

D. None of these

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Which of the following low melting alloy containing bismuth and lead is used for electric fuse?

A. Wood's metal

B. Babbitt metal

C. Monel metal

D. Duralumin

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Addition of small amount of __________ to grey cast iron is done to produce nodular grey cast iron.

A. Manganese

B. Phosphorous

C. Magnesium

D. Chromium

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Oxyacetylene reducing flame is used while carrying out welding on

A. Alloy steel

B. Grey cast iron

C. Mild steel

D. High carbon steel

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In case of compression of one kg of air, the work done will be the least, when the value of polytropic index 'n' is

A. 1

B. 1.4

C. 1.5

D. Y = Cp/Cv

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A thin, flat & square plate measuring 2 m × 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2. The plate temperature will remain constant at 30°C, if the convective heat transfer co-efficient is __________ W/m2 °C.

A. 50

B. 100

C. 150

D. 200

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Tesla metre per ampere (T. m/A) is the unit for the measurement of

A. Magnetic susceptibility

B. Magnetic moment

C. Permeability of free space

D. Flux density

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Yield strength of a polycrystalline metal with an average grain size d, is proportional to

A. d1/2

B. d-1/2

C. d

D. d-1