Softening of hardened steel is done by its
Normalising
Tempering
Annealing
Carburising
Correct Answer :
A. Normalising
Related Questions
A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place
The better insulation material should be put just next to pipe (i.e., inside)
The better insulating material should be put outside
Either of the insulating material could be put on either side
Steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe)
Out of the following, the __________ pipe has the least corrosion resistance.
Mild steel
Copper
Cast iron
Wrought iron
Transformer cores are normally made from
Soft ferrites
High purity iron
Grain oriented Fe-Si alloy
Al-Ni-Co alloy
The minimum and the maximum number of members required to form a Private Limited Joint Stock Company are respectively
7 and 30
10 and 50
2 and 50
13 and 55
A material being tested for endurance strength is subjected to the __________ load.
Impact
Completely reversed
Dynamic
Static & dynamic
Globular form of cementite is formed during the __________ process.
Spheroidising
Hardening
Annealing
Normalising
'Cryogenics' is concerned with the generation & use of low temperature in the range of
0°K to 123°K
0°C to - 123°C
0°C to - 273°C
0°K to 273°K
Even though heat transfer co-efficient in boiling liquids is large, use of fins is advantageous, when the entire surface is exposed to __________ boiling.
Film
Nucleate
Transition
All modes of
In case of condensers & evaporators operating under given terminal conditions, LMTD (logarithmic mean temperature difference) for counter flow as compared to that for parallel flow is
More
Less
Equal
Much more
Function of fusible plug in a boiler is to
Drain out water and sludge from the boiler during repair
Put off fire in the furnace when water level in the boiler falls to unsafe limit
Guard the boiler in case of abnormal rise in steam pressure
All (A), (B) & (C)
The swift cup test evaluates the following property of a sheet metal.
Stretchability
Drawability
Bendability
None of these
Large diameter reinforced cement concrete (RCC) pipes are generally joined by __________ joint.
Flanged iron
Collar
Flexible
Expansion
Case hardening of a material is
Followed by tempering or carburising
Preceded by its tempering
Done to get a soft ductile interior with a very hard surface
Carried out to get extreme hardness in its core
Out of the following, maximum temperature drop for a given heat flow & for the same thickness will be in the case of
Steel
Glass wood
Copper
Fireclay bricks
__________ has a negative co-efficient of linear expansion.
Iron
Copper
Rubber
Nickel
Maximum permissible sulphur content in steel is __________ percent.
0.015
0.055
0.505
0.805
Vernier calipers cannot be used to measure the
I.D. & O.D. of the shaft
Thickness of parts
Depth of holes
Clearance between two mating surfaces
Pressure required to increase the density of water by about 1% is __________ atmosphere.
10
50
200
1000
The noble metals
Are exemplified by Na, K and Li
Do not resist corrosion very strongly
Are the lowermost in the electro-chemical series of metals
None of these
Tin based white metals are used, where bearings are subjected to
High pressure & load
Low pressure & load
High temperature
Large surface wear
__________ cannot increase the fatigue strength of a material.
Grain refining
Grain coarsening
Surface hardening
Shot peening
Silicon in steel
Makes it usable in almost all magnetic circuits where alternating current is used
Increases its electrical resistivity and decreases the hysteresis loss
Is present upto 5% & 4% respectively when used in transformers & motor armatures
All 'a', 'b' & 'c'
Resistance of an electrical conductor is proportional to its (where, l = length and A = cross-sectional area of the conductor)
A
l
A2
Both 'a' & 'b'
Pick out the wrong statement.
The equivalent stiffness of two springs (of equal stiffness 'S') in series is S/2 while in parallel is 2S
For a helical spring, deflection is proportional to D3 (D = mean coil diameter) or d4 (d = wire diameter)
Crushing load or columns is less than the buckling load
Modulus of resilience is proportional to (stress at elastic limit)2
The highest stress that a material can withstand for a specified length of time without excessive deformation is called the __________ strength.
Creep
Endurance
Fatigue
None of these
Magnetic permeability of iron is increased by its
Decarburising
Alloying with cobalt
Purification
Alternate heating & cooling
The temperature at which the magnetic property of iron disappears (i.e., it becomes non-magnetic) and its electrical conductivity & specific heat also changes, is called the 'Curie point', which is __________ °C.
768
908
1400
1539
Basic open hearth furnace (BOF) is not used for producing __________ steel.
Killed
Rimming
High alloy
None of these
Steel is welded using the __________ flame.
Carburising
Neutral
Oxidising
All (A), (B) & (C)
A high pressure boiler generates steam at a pressure greater than __________ kg/cm2.
10
30
50
80