Ferromagnetic alpha iron exists in temperature range of________________?
(A) below 723°C
(B) 770 – 910°C
(C) 910-1440°C
(D) 1400-1539°C
(D) above 1539°C
The temperature at which ferromagnetic alpha iron transforms to paramagnetic alpha iron is _______________?
(A) 770°C
(B) 910°C
(C) 1050°C
(D) below recrystallisation temperature
(D) above recrystallization temperature
Which of the following constituents of steels is softest and least strong ________________?
(A) austenite
(B) pearlite
(C) ferrite
(D) cementlte
(D) bainite
A material is known as allotropic or polymorphic if it __________________?
(A) has a fixed structure under all conditions
(B) exists in several crystal forms at different temperatures
(C) responds to heat treatment
(D) has its atoms distributed in a random pattern
(D) none of the above
Points of arrest for iron correspond to__________________?
(A) stages at which allotropic forms change
(B) stages at which further heating does not increase temperature for some time
(C) stages at which properties do not change with increase in temperature
(D) there is nothing like points of arrest
(D) none of the above
Annealing of white cast iron results in production of_________________?
(A) malleable iron
(B) nodular iron
(C) spheroidal iron
(D) grey iron
(D) none of the above
Steel contains____________________?
(A) 80% or more iron
(B) 50% or more iron
(C) alloying elements like chromium, tungsten nickel and copper
(D) elements like phosphorus, sulphur and silicon in varying quantities
(D) high quantities of sulphur
An important property of high silicon (12 – 18%) cast iron is the high__________________?
(A) tenacity
(B) brittleness
(C) plasticity
(D) corrosion resistance
(D) hardness
White cast iron contains carbon in the form of__________________?
(A) free carbon
(B) graphite
(C) cementite
(D) white carbon
(D) ferrite
Chilled cast iron has____________________?
(A) no graphite
(B) a very high percentage of graphite
(C) a low percentage of graphite
(D) graphite as its basic constituent of composition
(D) none of the above is true