A material is known as allotropic or polymorphic if it
Has a fixed structure under all conditions
Exists in several crystal forms at different temperatures
Responds to heat treatment
Has its atoms distributed in a random pattern
Correct Answer :
B. Exists in several crystal forms at different temperatures
Related Questions
The ability of a material to resist softening at high temperature is known as
Creep
Hot tempering
Hot hardness
Fatigue
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
The material in which the atoms are arranged chaotically, is called
Amorphous material
Mesomorphous material
Crystalline material
None of these
An engineer's hammer is made of
Cast iron
Forged steel
Mild steel
High carbon steel
Vanadium in high speed steels
Promotes decarburisation
Provides high hot hardness
Forms very hard carbides and thus increases wear resistance
Promotes retention of austenite
Eutectoid steel contains following percentage of carbon
0.02 %
0.3 %
0.63 %
0.8 %
Age-hardening is related with
Stainless steel
Gun metal
German silver
Duralumin
Lead is poured into the joint between two pipes. These pipes may be made of
Cast iron
Vitrified clay
Asbestos cement
Concrete
Manganese is added in low carbon steel to
Make the steel tougher and harder
Raise the yield point
Make the steel ductile and of good bending qualities
All of the above
Age hardening is related to
Duralumin
Brass
Copper
Silver
The temperature at which ferromagnetic alpha iron transforms to paramagnetic alpha iron is
770°C
910°C
1050°C
Below recrystallisation temperature
Dye penetrant method is generally used to locate
Core defects
Surface defects
Superficial defects
Temporary defects
Wrought iron
Is a ductile material
Can be easily forged or welded
Cannot stand sudden and excessive shocks
All of these
The alloy, mainly used for corrosion resistance in stainless steels is
Silicon
Manganese
Carbon
Chromium
Chromium in steel
Improves wear resistance, cutting ability and toughness
Refines grain size and produces less tendency to carburisation, improves corrosion and heat resistant properties
Improves cutting ability and reduces hardenability
Gives ductility, toughness, tensile strength and anticorrosion properties
Eutectoid reaction occurs at
600°C
723°C
1147°C
1493°C
Hardness of steel depends on
Amount of carbon it contains
The shape and distribution of the carbides in iron
Method of fabrication
Contents of alloying elements
Connecting rod is usually made of
Aluminium
Low carbon steel
Medium carbon steel
High carbon steel
Free cutting steels
Are used where ease in machining is the criterion
Contain carbon in free form
Require least cutting force
Do not exist
Amorphous material is one
In which atoms align themselves in a geometric pattern upon solidification
In which there is no definite atomic structure and atoms exist in a random pattern just as in a liquid
Which is not attacked by phosphorous
Which emits fumes on melting
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
Elinvar, an alloy used in precision instruments, hair springs for watches, etc. contains the following element as principal alloying element
Iron
Copper
Aluminium
Nickel
Aluminium bronze contains
94% aluminium, 4% copper and 0.5% Mn, Mg, Si and Fe
92.5% aluminium, 4% copper, 2% nickel, and 1.5% Mg
10% aluminium and 90% copper
90% magnesium and 9% aluminium with some copper
Specify the sequence correctly
Grain growth, recrystallisation, stress relief
Stress relief, grain growth, recrystallisation
Stress relief, recrystallisation, grain growth
Grain growth, stress relief, recrystallisation
The transistor is made of
Silver
Gold
Copper
Germanium
Pick up the wrong statement Nickel and chromium in steel help in
Providing corrosion resistance
Improving machining properties
Providing high strength at elevated temperatures
Raising the elastic limit
A cold chisel is made of
Mild steel
Cast iron
HSS
High carbon
By severely deforming a metal in a particular direction it becomes
Ductile
Malleable
Homogeneous
Anisotropic
'Killed steels' are those steels
Which are destroyed by burning
Which after their destruction are recycled to produce fresh steel
Which are deoxidised in the ladle with silicon and aluminium
In which carbon is completely burnt