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Which of the following is not a characteristic observed in material failure by fatigue fracture?

A. Plastic deformation of material does not occur

B. Initiation of crack from below the surface does not occur

C. Initiation of crack occurs on the surface of the machine part

D. Presence of both rough & smooth zone with conchoidal markings in smooth zone of the surface

Correct Answer :

B. Initiation of crack from below the surface does not occur


Related Questions

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A dense structure of grinding wheel is not used for the

A. Ductile material

B. Hard materials

C. Brittle materials

D. Finishing cuts

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4

Pick out the wrong statement about coating/electroplating of metals.

A. Phosphate coating is used as an excellent base for paints & enamels

B. Phosphate coating is less corrosion resistant than chromate coating

C. The base metal to be electroplated is normally made the cathode of the electrolytic cell and coating metal is made the anode

D. Calorising is the process of coating steel with chromium

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4

Electrical conductivities of semi-conductors are of the order of __________ ohm/cm.

A. 10-3

B. 103

C. 10-15

D. 1015

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4

Air/fuel ratio on molar (volume) basis for combustion of methane with theoretical quantity of air with be

A. 9.5 : 1

B. 12.5 : 1

C. 15.5 : 1

D. 18.5 : 1

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4

Out of the following, the __________ pipe has the least corrosion resistance.

A. Mild steel

B. Copper

C. Cast iron

D. Wrought iron

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4

Good design of the casing of a centrifugal pump aims at minimising the

A. Cavitation

B. Frictional losses

C. Kinetic energy loss

D. Static head

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4

Pick out the wrong statement.

A. Lead can creep under its own weight at room temperature

B. The electrical conductivity of gold is considerably reduced by alloying additions due to the decrease in electron movement

C. Recrystallisation temperature decreases with decrease in strain in a cold worked metal

D. With increase in temperature, the electrical conductivity of intrinsic semi-conductor will increase

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4

Square steel key is normally strong in failure by shear & crushing. Keys are normally made of __________ steel bars.

A. Hot rolled mild

B. Cold rolled mild

C. Forged

D. Machinable stainless

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4

If Reynolds number is greater than 1, then the

A. Viscous force is larger than the inertia force

B. Inertia force is larger than the viscous force

C. Inertia force is larger than the surface tension force

D. Inertia force is larger than the gravitational force

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4

Elimination of brittleness resulting from welding of saw blades is done by __________ of the welded portion.

A. Annealing

B. Toughening

C. Work hardening

D. Tempering

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4

Consideration of the creep is the most important in case of the

A. Blades of gas turbine

B. Piston of an I. C. engine

C. Flywheel of steam engine

D. Cycle chain

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4

Leakage in a cooking gas cylinder is detected by

A. Radio-isotopes

B. Pouring soap solution on the surface and locating the gas bubbles

C. Halide torch

D. Pungent smell of mercaptans present in the gas

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4

A polymer is termed as an 'elastomer', if its percentage elongation is more than 100%. An elastomer is termed as 'rubber' if its percentage elongation is more than __________ percent.

A. 150

B. 200

C. 300

D. 400

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4

Basicity of the slag in Indian blast furnace is in the range of

A. 0.7-1.0

B. 1.1-1.4

C. 1.5 - 1.8

D. 2.0 - 2.5

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4

In a drilling process, the metal is removed by both shearing & extrusion. General purpose drills are made of

A. Stainless steel

B. Mild steel

C. High speed steel

D. High carbon steel

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4

__________ is not used as the control rod material in a nuclear reactor.

A. Cobalt

B. Hafnium

C. Cadmium

D. Boron

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4

Diameter of the rivet to be provided on a 20 mm. thick boiler plate will be __________ mm.

A. 10

B. 20

C. 30

D. 40

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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

Reduction in the grain size reduces the __________ of the material.

A. Fatigue resistance

B. Tensile strength

C. Creep resistance

D. All (A), (B) & (C)

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4

The ratio of the shear stress to the principal stress on a principal plane is

A. 0

B. 1

C. 1/2

D. 1/3

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4

Moist climate is the most favourable factor in the site selection far a

A. Steel plant

B. Textile factory

C. Petroleum refinery

D. Coke oven battery

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4

The expected efficiency of a single riveted lap joint is of the order of 50%. If the thickness of the plate is increased four times, then the rivet diameter will have to be increased __________ times.

A. Two

B. Four

C. Six

D. Eight

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4

Function of gear box is to

A. Reduce the speed

B. Obtain variable speed

C. Increase the speed

D. Produce high torque

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4

Which of the following pairs is not correctly matched?

A. Uranium - 233 : Fertile material

B. Binding energy : Mass defect

C. Scattering: Absorption cross-section

D. Number of nucleons : Mass number

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4

Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of

A. Grashoff number

B. Grashoff number & Reynolds number

C. Reynolds number

D. Grashoff number & Prandtl number

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4

Which of the following equipments is used for liquid dispersion?

A. Packed column

B. Venturi scrubber

C. Bubble cap plate column

D. Wetted wall column

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4

The hardenability of steel decreases with

A. Decrease in dislocation density

B. Increase in solutionising temperature

C. Increase in strength

D. Decrease in grain size

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4

Which one can be directly solidified from gaseous state without entering into liquid state?

A. Helium

B. Oxygen

C. Carbon dioxide

D. None of these

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4

Pick out the wrong statement.

A. Complete unity of command exists in a line organisation

B. Line organisation is net suitable for expansion and growth of an industry

C. In line and staff organisation, line executes and staff directs

D. None of these

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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