Identify the false statement
Martensitic steels are less susceptible to pitting corrosion than austenitic steels
Pitting corrosion is usually very localised
Hydrogen embrittlement is facilitated by tensile stress
Stress corrosion cracking is facilitated by tensile stress
Correct Answer :
A. Martensitic steels are less susceptible to pitting corrosion than austenitic steels
Related Questions
The swift cup test evaluates the following property of a sheet metal.
Stretchability
Drawability
Bendability
None of these
A particle is settling in a liquid under Stokesian conditions. The free falling velocity of the particle is proportional to
√(Particle diameter)
Particle diameter
(Particle diameter)2
(Particle diameter)3
Carbon is present in the form of __________ in grey cast iron.
Spheroids
Nodular aggregates of graphite
Flakes
Cementite
A fluid is termed as the Newtonian fluid, when the shear stress is __________ the velocity gradient.
Independent of
Inversely proportional to
Directly proportional to
None of these
Change in volume of metals from absolute zero temperature to their melting points is
Almost same for all metals
Different for different metals
Less for low melting point metals
Less for high melting point metals
While the oxy-acetylene flame produces a temperature of 3200°C, the temperature produced by oxy-hydrogen flame is about __________ °C.
1800
2000
2400
3000
A spring material should have low
Elastic limit
Deflection value
Fatigue resistance
None of these
Sub zero treatment of steel is done to
Suppress martensite transformation
Enhance its working performance in sub zero atmosphere
Reduce the retained austenite in hardened steel
Induce temper brittleness after its hardening
Magnesium is present in
Haemoglobin
Chlorophyll
Hypo solution
None of these
Pick out the correct statement
Jet engine can work, where there is no atmosphere
Rocket engines cannot work, where there is no atmosphere
Rocket engines carry oxygen required for the combustion in the form of oxidiser
Jet engines also carry oxidiser
The mechanism which changes the value of manipulated variable in response to the output signal from the control unit is called the
Final control element
On-off control
Floating control action
None of these
The maximum thickness of the metal which can be welded using ultrasonic welding is __________ mm.
0.5
3
10
25
A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness __________ metre.
0.01
0.1
0.25
0.5
The normal stress is the same in all directions at a point in a fluid, only when the fluid
Is at rest & has zero viscosity
Is frictionless
Fluid layer has no motion relative to an adjacent layer of fluid
is incompressible & frictionless
Silicon percentage in acid resistant cast iron is about
4
8
14
20
Unit of surface tension in S.I. unit is
Watt/m
Joule/
Newton/
Joule/m
Compressed dry air is used as the cutting fluid, while machining
Steel
Cast iron
Aluminium
None of these
Alloying elements present in Haynes stellite, which has superior performance than high speed steel, are:
Nickel, cobalt & chromium
Tungsten, chromium & cobalt
Manganese, chromium & cobalt
Tungsten, molybdenum & nickel
Electrical conductivities of semi-conductors are of the order of __________ ohm/cm.
10-3
103
10-15
1015
Which of the following is the largest quantum of pressure?
1 kg/cm2
1 bar
1 atmosphere
1 kilo Pascal
Which of the following is an example of cathodic protection of metals against corrosion?
Painted steel
Galvanised iron
Case hardened steel
Lead lined reactor
Maximum amount of thermal radiation is emitted at all wavelengths at any specified temperature by a/an __________ body.
Grey
Black
Opaque
White
The kinematic viscosity (in stoke) and the absolute/dynamic viscosity (in poise) are the same for __________ at room temperature.
Air
Water
Mercury
Alcohol
Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans?
Emissivity of pipe surface
Diameter & length of the pipe
Temperature of hot pipe surface & that of air in the room
None of these
Out of the following, which will fracture most readity, when hit with a hard hammer?
Brass
Bronze
German silver
Cast iron
Carnot cycle is also termed as the constant __________ cycle in thermodynamics.
Entropy
Pressure
Volume
Heat
What is the percentage of chromium in 18-4-1 high speed steel?
1
4
18
23
Gratings is associated with the measurement of
Linear displacement
Concavity/convexity
Surface texture
Flatness
Material of construction of foundry crucible is
Lead
Stainless steel
Graphite
Cast iron
Nusselt number is related to the Reynolds number (Re) in turbulent & laminar flow respectively as
Re0.5, Re0.8
Re0.8, Re-0.5
Re0.8, Re0.5
Re-0.8, Re0.5