The defect which takes place due to imperfect packing of atoms during crystallisation is known as
Line defect
Surface defect
Point defect
None of these
Correct Answer :
C. Point defect
Related Questions
Beryllium bronze has
High yield point
High fatigue limit
Both (A) and (B)
None of these
Gamma iron exits at following temperature
Room temperature
Near melting point
Between 1400°C and 1539°C
Between 910°C and 1400°C
Connecting rod is, usually, made from
Low carbon steel
High carbon steel
Medium carbon steel
High speed steel
German silver contains
1% silver
2.5% silver
5% silver
10% silver
The steel widely used for motor car crankshafts is
Nickel steel
Chrome steel
Nickel-chrome steel
Silicon steel
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
Acidic solution is one which has pH value
Greater than 7
Less than 7
Equal to 7
pH value has nothing to do with neutral solution
Paramagnetic alpha iron changes to gamma iron at
770°C
910°C
1440°C
1539°C
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
The ratio of the volume occupied by the atoms to the total volume of the unit cell is called
Coordination number
Atomic packing factor
Space lattice
None of these
Gun metal contains
70% copper and 30% zinc
90% copper and 10% tin
85 - 92% copper and rest tin with little lead and nickel
70 - 78% copper and rest tin
Weld decay is the phenomenon found with
Cast iron
Mild steel
Nonferrous materials
Stainless steel
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
Sulphur in steel
Acts as deoxidiser
Reduces the grain size
Decreases tensile strength and hardness
Lowers the toughness and transverse ductility
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
The elastic stress strain behaviour of rubber is
Linear
Nonlinear
Plastic
No fixed relationship
Y-alloy contains
3.5 to 4.5% copper, 0.4 to 0.7% magnesium, 0.4 to 0.7% manganese and rest aluminium
3.5 to 4.5% copper, 1.2 to 1.7% manganese, 1.8 to 2.3% nickel, 0.6% each of silicon, magnesium and iron, and rest aluminium
4 to 4.5% magnesium, 3 to 4% copper and rest aluminium
5 to 6% tin, 2 to 3% copper and rest aluminium
In spheroidising process, the steel is
Heated below the lower critical temperature and then cooled slowly
Heated up to the lower critical temperature and then cooled in still air
Heated slightly above the lower critical temperature and then cooled slowly to a temperature of 600°C
None of the above
Which of the following impurity in cast iron promotes graphite nodule formation and increases the fluidity of the molten metal?
Silicon
Sulphur
Manganese
Phosphorus
The ability of a material to resist fracture due to high impact loads, is called
Strength
Stiffness
Toughness
Brittleness
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
Iron-carbon alloys containing 1.7 to 4.3% carbon are known as
Eutectic cast irons
Hypoeutectic cast irons
Hypereutectic cast irons
None of these
Coarse grained steel
Is less tough and has a greater tendency to distort during heat treatment
Is more ductile and has a less tendency to distort during heat treatment
Is less tough and has a less tendency to distort during heat treatment
Is more ductile and has a greater tendency to distort during heat treatment
Drop forging dies contain carbon of the order of
0.1 to 0.2 %
0.25 to 0.5 %
0.6 to 0.7 %
0.7 to 0.9 %
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 material in which the atoms are arranged chaotically, is called
Amorphous material
Mesomorphous material
Crystalline material
None of these
Malleable cast iron
Contains 1.7 to 3.5% carbon in Free State and is obtained by the slow cooling of molten cast iron
Is also known as chilled cast iron and is obtained by cooling rapidly. It is almost unmachinable
Is produced by annealing process. It is soft, tough, and easily machined metal
Is produced by small additions of magnesium (or cerium) in the ladle. Graphite is in the nodular or spheroidal form and is well dispersed throughout the material
Which of the following statement is incorrect about duralumin?
It is prone to age hardening
It can be forged
It has good machining properties
It is lighter than pure aluminium
The percentage carbon content in wrought iron is about
0.02
0.1
02
0.4
A material is said to be allotropic, if it has
Fixed structure at all temperatures
Atoms distributed in random pattern
Different crystal structures at different temperatures
Any one of the above