The presence of hydrogen in steel causes
Reduced neutron absorption cross-section
Improved Weldability
Embrittlement
Corrosion resistance
Correct Answer :
C. Embrittlement
Related Questions
Depth of hardness of steel is increased by addition of
Nickel
Chromium
Tungsten
Vanadium
In a hardening process, the hypo-eutectoid steel is
Heated from 30°C to 50°C above the upper critical temperature and then cooled in still air
Heated from 30°C to 50°C above the upper critical temperature and then cooled suddenly in a suitable cooling medium
Heated from 30°C to 50°C above the upper critical temperature and then cooled slowly in the furnace
Heated below or closes to the lower critical temperature and then cooled slowly
Thermoplastic materials are those materials which
Are formed into shape under heat and pressure and results in a permanently hard product
Do not become hard with the application of heat and pressure and no chemical change occurs
Are flexible and can withstand considerable wear under suitable conditions
Are used as a friction lining for clutches and brakes
The correct sequence for descending order of machinability is
Grey cast iron, low carbon steel, wrought iron
Low carbon steel, grey cast iron, wrought iron
Wrought iron, low carbon steel, grey cast iron
Wrought iron, grey cast iron, low carbon steel
Monel metal contains
63 to 67% nickel and 30% copper
88% copper and 10% tin and rest zinc
Alloy of tin, lead and cadmium
Malleable iron and zinc
Large forgings, crank shafts, axles normally contain carbon up to
0.05 to 0.20 %
0.20 to 0.45 %
0.45 to 0.55 %
0.55 to 1.0 %
Super conduction by metals is observed in the temperature range of
Below 10°K
Above 100°K
Around 0°C
Around 100°C
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
The maximum internal diameter of a blast furnace is about
3 m
6 m
9 m
12 m
Materials after cold working are subjected to following process to relieve stresses
Hot working
Tempering
Normalising
Annealing
When filing or machining cast iron makes our hands black, then it shows that ________ is present in cast iron.
Cementite
Free graphite
Both A and B
None of these
In nodular iron, graphite is in the form of
Cementite
Free carbon
Flakes
Spheroids
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
Which of the following constituents of steels is softest and least strong?
Austenite
Pearlite
Ferrite
Cementite
The type of space lattice found in gamma-iron is
Face centered cubic space lattice
Body centered cubic space lattice
Close packed hexagonal space lattice
None of these
Blast furnace is used to produce
Pig iron
Cast iron
Wrought iron
Steel
The lower critical temperature
Decreases as the carbon content in steel increases
Increases as the carbon content in steel increases
Is same for all steels
Depends upon the rate of heating
White cast iron has
Carbon in the form of carbide
Low tensile strength
High compressive strength
All 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
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 hardness of steel increases if it contains
Pearlite
Ferrite
Cementite
Martensite
Cast iron is a
Ductile material
Malleable material
Brittle material
Tough material
A reversible change in the atomic structure of steel with corresponding change in the properties is known as
Molecular change
Physical change
Allotropic change
Solidus change
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
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
White cast iron contains carbon in the form of
Free carbon
Graphite
Cementite
White carbon
The molecules in a solid move
In a random manner
In a haphazard way
In circular motion
Back and forth like tiny pendulums
Age-hardening is related with
Stainless steel
Gun metal
German silver
Duralumin
Normalising of steel is done to
Refine the grain structure
Remove strains caused by cold working
Remove dislocations caused in the internal structure due to hot working
All of the above
The compressive strength of cast iron is ________ that of its tensile strength.
Equal to
Less than
More than
None of these