Austenite is a combination of
Ferrite and cementite
Cementite and gamma iron
Ferrite and austenite
Ferrite and iron graphite
Correct Answer :
B. Cementite and gamma iron
Related Questions
When elements like nickel, chromium, copper and molybdenum are added to the molten cast iron, it produces
White cast iron
Nodular cast iron
Malleable cast iron
Alloy cast iron
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
Super conduction by metals is observed in the temperature range of
Below 10°K
Above 100°K
Around 0°C
Around 100°C
Which of the following steel making process is being adopted at Rourkela (in India) Steel Plant?
Bessemer process
Open hearth process
Electric process
LD process
Which is false statement about normalizing? Normalizing is done to
Refine grain structure
Reduce segregation in casting
Improve mechanical properties
Induce stresses
Pick up wrong statement about wrought iron
It contains carbon of the order of 0 to 0.25%
It melts at 1535°C
It is very soft and ductile
It is made by adding suitable percentage of carbon to molten iron and subjecting the product to repeated hammering and rolling.
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
Structural steel contains following principal alloying elements
Nickel, chromium and manganese
Tungsten, molybdenum and phosphorous
Lead, tin, aluminium
Zinc, sulphur, and chromium
An important property of malleable cast iron in comparison to grey cast iron is the high
Compressive strength
Ductility
Carbon content
Hardness
Dow metal contains
94% aluminium, 4% copper and 0.5% Mn, Mg, Si and Fe
92.5% aluminium and, 4% copper, 2% nickel and 1.5% Mg
90% aluminium and 90% copper
90% magnesium and 9% aluminium with some copper
Lead is poured into the joint between two pipes. These pipes may be made of
Cast iron
Vitrified clay
Asbestos cement
Concrete
In nodular iron, graphite is in the form of
Cementite
Free carbon
Flakes
Spheroids
Quenching is not necessary when hardening is done by
Case hardening
Flame hardening
Nitriding
Any one of these
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
Addition of lead and bismuth to aluminium results in
Improvement of casting characteristics
Improvement of corrosion resistance
One of the best known age and precipitation hardening systems
Improving machinability
Recrystallisation temperature can be lowered by
Purification of metal
Grain refinement
Working at lower temperature
All of the above
High carbon steel carries carbon percentage
0.1 to 0.3 %
0.3 to 0.6 %
0.6 to 0.8 %
0.8 to 1.5 %
The machinability of steel is increased by
Silicon and sulphur
Phosphorous, lead and sulphur
Sulphur, graphite and aluminium
Phosphorous and aluminium
Process of Austempering results in
Formation of bainite structure
Carburised structure
Martenistic structure
Lamellar layers of carbide distributed throughout the structure
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
Hematite iron ore contains iron about
30 %
45 %
55 %
70 %
Points of arrest for iron correspond to
Stages at which allotropic forms change
Stages at which further heating does not increase temperature for some time
Stages at which properties do not change with increase in temperature
There is nothing like points of arrest
Elinvar, an alloy used in precision instruments, hair springs for watches, etc. contains the following element as principal alloying element
Iron
Copper
Aluminium
Nickel
Induction hardening is the process of
Hardening surface of work-piece to obtain hard and wear resistant surface
Heating and cooling rapidly
Increasing hardness throughout
Inducing hardness by continuous process
There are fourteen atoms in a unit cell of
Body centred cubic space lattice
Face centred cubic space lattice
Close packed hexagonal space lattice
None of these
Sulphur in pig iron tends to make it
Hard
Soft
Ductile
Tough
German silver contains
1% silver
2% silver
5% silver
No silver
Steel containing ferrite and pearlite is
Hard
Soft
Tough
Hard and tough
Materials after cold working are subjected to following process to relieve stresses
Hot working
Tempering
Normalising
Annealing
Preheating is essential in welding
Cast iron
High speed steel
All nonferrous materials
All of the above