In induction hardening ________ is high.
Current
Voltage
Frequency
Temperature
Correct Answer :
C. Frequency
Related Questions
The property of a material which enables it to retain the deformation permanently, is called
Brittleness
Ductility
Malleability
Plasticity
Which of the following impurity in cast iron promotes graphite nodule formation and increases the fluidity of the molten metal?
Silicon
Sulphur
Manganese
Phosphorus
Closed packed hexagonal space lattice is found in
Zinc, magnesium, cobalt, cadmium, antimony and bismuth
Gamma-iron, aluminium, copper, lead, silver and nickel
Alpha-iron, tungsten, chromium and molybdenum
None of the above
The following types of materials are usually the most ductile
Face centred cubic lattice
Body centred cubic lattice
Hexagonal close packed lattice
All of the above
Which is false statement about annealing? Annealing is done to
Relieve stresses
Harden steel slightly
Improve machining characteristic
Soften material
Preheating is essential in welding
Cast iron
High speed steel
All nonferrous materials
All of the above
Which is false statement about normalizing? Normalizing is done to
Refine grain structure
Reduce segregation in casting
Improve mechanical properties
Induce stresses
When a steel containing ________ 0.8% carbon is cooled slowly below the lower critical point, it consists of ferrite and pearlite.
Equal to
Less than
More than
None of these
The material widely used for making pendulums of clocks is
Stainless steel
High speed steel
Heat resisting steel
Nickel steel
Which of the following impurity in cast iron makes it hard and brittle?
Silicon
Sulphur
Manganese
Phosphorus
The hardness is the property of a material due to which it
Can be drawn into wires
Breaks with little permanent distortion
Can cut another metal
Can be rolled or hammered into thin sheets
Tungsten in high speed steel provides
Hot hardness
Toughness
Wear resistance
Sharp cutting edge
The hardness of steel primarily depends on
Percentage of carbon
Percentage of alloying elements
Heat treatment employed
Shape of carbides and their distribution in iron
Recrystallisation temperature is one
At which crystals first start forming from molten metal when it is cooled
At which new spherical crystals first begin to form from the old deformed one when a strained metal is heated
At which change of allotropic form takes place
At which crystals grow bigger in size
Hardness of upper bainite (acicular structure) is about
RC 65
RC 48
RC 57
RC 80
Bronze is an alloy of
Copper and zinc
Copper and tin
Copper, tin and zinc
None of these
Which of the following material has nearly zero coefficient of expansion?
Stainless steel
High speed steel
Invar
Heat resisting steel
For the allotropic forms of iron, the points of arrest are
The points where no further change occurs
Constant for all metals
The points where there is no further flow of metal
The points of discontinuity
The hardness and tensile strength in austenitic stainless steel can be increased by
Hardening and cold working
Normalising
Martempering
Full annealing
The addition of which of the following improves machining of copper?
Sulphur
Vanadium
Tin
Zinc
Ductility of a material can be defined as
Ability to undergo large permanent deformations in compression
Ability to recover its original form
Ability to undergo large permanent deformations in tension
All of the above
Which of the following is not the correct method of increasing fatigue limit?
Shot peening
Nitriding of surface
Cold working
Surface decarburisation
The metal suitable for bearings subjected to heavy loads, is
Silicon bronze
White metal
Monel metal
Phosphor bronze
Pick up the wrong statement
Aluminium in steel results in excessive grain growth
Manganese in steel induces hardness
Nickel and chromium in steel helps in raising the elastic limit and improve the resilience and ductility
Tungsten in steels improves magnetic properties and hardenability
The percentage of carbon in grey iron castings usually varies between
0.5 to 1 %
1.2 %
2.5 to 4.5 %
5 to 7 %
Cast iron has
High tensile strength
Its elastic limit close to the ultimate breaking strength
High ductility
All of the above
Cast iron is a
Ductile material
Malleable material
Brittle material
Tough material
Which of the following statement is correct?
The product produced by blast-furnace is called cast iron
The pig iron is the name given to the product produced by cupola
The cast iron has high tensile strength
The chilled cast iron has no graphite
In the lower part of the blast furnace (zone of fusion), the temperature is
400° to 700°C
800°C to 1000°C
1200°C to 1300°C
1500°C to 1700°C
Addition of silicon to aluminium results in
Improvement of casting characteristics
Improvement of corrosion resistance
One of the best known age and precipitation hardening systems
Improving machinability