For the allotropic forms of iron, the points of arrest are
The points where no further change occurs
Constant for all metals
The points where there is no further flow of metal
The points of discontinuity
Correct Answer :
D. The points of discontinuity
Related Questions
When medium carbon steel is heated to coarsening temperature
There is no change in grain size
The average grain size is a minimum
The grain size increases very rapidly
The grain size first increases and then decreases very rapidly
Eutectoid steel consists of
Wholly pearlite
Wholly austenite
Pearlite and ferrite
Pearlite and cementite
Dye penetrant method is generally used to locate
Core defects
Surface defects
Superficial defects
Temporary defects
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
In low carbon steels, presence of small quantities of sulphur improves
Weldability
Formability
Machinability
Hardenability
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
Pearlite is a combination of
Ferrite and cementite
Cementite and gamma iron
Ferrite and austenite
Ferrite and iron graphite
Iron-carbon alloys containing carbon ________ 4.3% are known as hypereutectic cast irons.
Equal to
Less than
More than
None of these
The temperature at which ferromagnetic alpha iron transforms to paramagnetic alpha iron is
770°C
910°C
1050°C
Below recrystallisation temperature
The coordination number of a face centred cubic space lattice is
Six
Twelve
Eighteen
Twenty
Which of the following statements are true for annealing of steels?
Steels are heated to 500 to 700°C
Cooling is done slowly and steadily
Internal stresses are relieved
All of these
The alloying element which reduces the formation of iron sulphide in steel is
Chromium
Nickel
Vanadium
Manganese
Weld decay is the phenomenon found with
Cast iron
Mild steel
Nonferrous materials
Stainless steel
Balls for ball bearings are made of
Cast iron
Mild steel
Stainless steel
Carbonchrome steel
The ultimate tensile strength and yield strength of most of the metals, when temperature falls from 0 to 100°C will
Increase
Decrease
Remain same
First increase and then decrease
Delta metal is an alloy of
Copper, zinc and iron
Iron, nickel and copper
Iron, lead and tin
Iron, aluminium and magnesium
Induction hardening is basically a
Carburising process
Surface hardening process
Core hardening process
None of these
Mild steel belongs to the following category
Low carbon steel
Medium carbon steel
High carbon steel
Alloy steel
Super conduction by metals is observed in the temperature range of
Below 10°K
Above 100°K
Around 0°C
Around 100°C
Gamma-iron occurs between the temperature ranges of
400°C to 600°C
600°C to 900°C
900°C to 1400°C
1400°C to 1530°C
When low carbon steel is heated up to upper critical temperature
There is no change in grain size
The average grain size is a minimum
The grain size increases very rapidly
The grain size first increases and then decreases very rapidly
The crystal of alpha iron is
Body centered cubic
Face centered cubic
Hexagonal close packed
Cubic structure
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
Which is false statement about properties of aluminium?
Modulus of elasticity is fairly low
Wear resistance is very good
Fatigue strength is not high
Creep strength limits its use to fairly low temperatures
Admiralty brass used for steam condenser tubes contains copper and zinc in the following ratio
50 : 50
30 : 70
70 : 30
40 : 60
Ductile 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 creium) in the ladle. Graphite is in nodular or spheroidal form and is well dispersed throughout the material
In compression, a prism of brittle material will break
By forming a bulge
By shearing along oblique plane
In direction perpendicular to application of load
By crushing into thousands of pieces
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
Cartridge brass can be
Cold rolled into sheets
Drawn into wires
Formed into tube
Any one of these
Corrosion resistance of steel is increased by adding
Chromium and nickel
Nickel and molybdenum
Aluminium and zinc
Tungsten and sulphur