The alloying element which increases residual magnetism and coercive magnetic force in steel for magnets is
Chromium
Nickel
Vanadium
Cobalt
Correct Answer :
D. Cobalt
Related Questions
The machinability of aluminium increases when __________ is added to aluminium.
Copper
Magnesium
Silicon
Lead and bismuth
Free carbon in iron makes the metal
Soft and gives a coarse grained crystalline structure
Soft and gives a fine grained crystalline structure
Hard and gives a coarse grained crystalline structure
Hard and gives a fine grained crystalline structure
Which of the following material has nearly zero coefficient of expansion?
Stainless steel
High speed steel
Invar
Heat resisting steel
The crystal structure of gamma iron is
Body centered cubic
Face centred cubic
Hexagonal close packed
Cubic structure
Which is the false statement about wrought iron? It has
High resistance to rusting and corrosion
High ductility
Ability of hold protective coating
Uniform strength in all directions
Eutectoid steel contains following percentage of carbon
0.02 %
0.3 %
0.63 %
0.8 %
Tensile strength of steel can be safely increased by
Adding carbon up to 2.8%
Adding carbon up to 6.3%
Adding carbon up to 0.83%
Adding small quantities of copper
Addition of manganese to aluminium results in
Improvement of casting characteristics
Improvement of corrosion resistance
One of the best known age and precipitation hardening systems
Improving machinability
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
Isotropic materials are those which have the same
Elastic properties in all directions
Stresses induced in all directions
Thermal properties in all directions
Electric and magnetic properties in all directions
An important property of malleable cast iron in comparison to grey cast iron is the high
Compressive strength
Ductility
Carbon content
Hardness
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 %
Which of the following alloys does not have copper as one of the constituents?
Delta metal
Monel metal
Constantan
Nichrome
Elinvar, an alloy used in precision instruments, hair springs for watches, etc. contains the following element as principal alloying element
Iron
Copper
Aluminium
Nickel
Babbitt metal is a
Lead base alloy
Copper base alloy
Tin base alloy
Cadmium base alloy
Steel made from phosphate iron is
Brittle
Hard
Ductile
Tough
The elastic stress strain behaviour of rubber is
Linear
Nonlinear
Plastic
No fixed relationship
The charge of the blast furnace consists of
Calcined ore (8 parts), coke (4 parts) and limestone (1 part)
Calcined ore (4 parts), coke (1 part) and limestone (8 parts)
Calcined ore (1 part), coke (8 parts) and limestone (4 parts)
Calcined ore, coke and limestone all in equal parts
In mottled cast iron, carbon is available in
Free form
Combined form
Nodular form
Partly in free and partly in combined state
German silver is an alloy of
Silver and some impurities
Refined silver
Nickel, Copper and zinc
Nickel and copper
The hardness and tensile strength in austenitic stainless steel can be increased by
Hardening and cold working
Normalising
Martempering
Full annealing
Muntz metal contains copper and zinc in the ratio of
50 : 50
40 : 60
60 : 40
20 : 80
Addition of copper to aluminium results in
Improvement of casting characteristics
Improvement of corrosion resistance
One of the best known age and precipitation hardening systems
Improving machinability
If a refractory contains high content of silicon, it means refractory is
Acidic
Basic
Neutral
Brittle
The coke in the charge of blast furnace
Controls the grade of pig iron
Acts as an iron bearing mineral
Supplies heat to reduce ore and melt the iron
Forms a slag by combining with impurities
Brass contains
70% copper and 30% zinc
90% copper and 10% tin
85 - 92% copper and rest tin with little lead and nickel
70 - 75% copper and rest tin
Sulphur in cast iron
Makes the iron soft and easily machinable
Increases hardness and brittleness
Make the iron white and hard
Aids fusibility and fluidity
Chromium when added to steel __________ the tensile strength.
Does not effect
Decreases
Increases
None of these
Malleability 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
The surface hardness of the following order is achieved by nitriding operation
600 VPN
1500 VPN
1000 to 1100 VPN
250 VPN