The lower critical point for all steels is
600°C
700°C
723°C
913°C
Correct Answer :
C. 723°C
Related Questions
Which of the following iron exist between 910°C and 1403°C?
α-iron
β-iron
γ-iron
δ-iron
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
Railway rails are normally made of
Mild steel
Alloy steel
High carbon
Tungsten steel
Induction hardening is basically a
Carburising process
Surface hardening process
Core hardening process
None of these
Lead is poured into the joint between two pipes. These pipes may be made of
Cast iron
Vitrified clay
Asbestos cement
Concrete
Carbon steel is
Made by adding carbon in steel
Refined from cast iron
An alloy of iron and carbon with varying quantities of phosphorus and sulphur
Extensively used for making cutting tools
The unique property of cast iron is its high
Malleability
Ductility
Surface finish
Damping characteristics
Cyaniding is the process of
Dipping steel in cyanide bath
Reacting steel surface with cyanide salts
Adding carbon and nitrogen by heat treatment of steel to increase its surface hardness
Obtaining cyanide salts
Paramagnetic alpha iron changes to gamma iron at
770°C
910°C
1440°C
1539°C
Tungsten 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
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
Mild steel belongs to the following category
Low carbon steel
Medium carbon steel
High carbon steel
Alloy steel
Cementite consist of
13% carbon and 87% ferrite
13% cementite and 87% ferrite
13% ferrite and 87% cementite
6.67% carbon and 93.33% iron
Wrought iron
Is a ductile material
Can be easily forged or welded
Cannot stand sudden and excessive shocks
All of these
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
Hematite iron ore contains iron about
30 %
45 %
55 %
70 %
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
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
The unit cells
Contain the smallest number of atoms which when taken together have all the properties of the crystals of the particular metal
Have the same orientation and their similar faces are parallel
May be defined as the smallest parallelepiped which could be transposed in three coordinate directions to build up the space lattice
All of the above
The loss of strength in compression with simultaneous gain in strength in tension due to overloading is known as
Hysteresis
Creep
Visco elasticity
Boeschinger effect
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
In grey cast iron, carbon is present in the form of
Cementite
Free carbon
Flakes
Spheroids
Corundum contains more than 95%
Steel
Al2O3
SiO2
MgO
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
Constantan an alloy used in thermocouples is an alloy of
Copper and tin
Copper and zinc
Copper and iron
Copper and nickel
When the steel is normalised, its
Yield point increases
Ductility decreases
Ultimate tensile strength increases
All of these
The maximum internal diameter of a blast furnace is about
3 m
6 m
9 m
12 m
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
Admiralty brass used for steam condenser tubes contains copper and zinc in the following ratio
50 : 50
30 : 70
70 : 30
40 : 60
According to Indian standard specifications, SG 400/15 means
Spheroidal graphite cast iron with B.H.N. 400 and minimum tensile strength 15 MPa
Spheroidal graphite cast iron with minimum tensile strength 400 MPa and 15 percent elongation
Spheroidal graphite cast iron with minimum compressive strength 400 MPa and 15 percent reduction in area
None of the above