⚙️Mechanical Engineering MCQs
Mechanical Engineering MCQs
488 MCQs21
Recrystallization temperature is one________________?
Aat which crystals first start forming from molten metal when it is cooled
Bat which new spherical crystals first begin to form from the old deformed one when a strained metal is heated
Cat which change of allotropic form takes place
Dat which crystals grow bigger in size E. at which crystals are destroyed on heating
22
Delta iron occurs at temperature of_______________?
Aroom temperature
Babove melting point
Cbetween 1400°C and 1539°C
Dbetween 910°C and 1400°C E. none of the above
23
Super conduction by metals is observed in the temperature range of_________________?
Abelow 10°K
Babove 100°K
Caround 0°C
Daround 100°C E. above 1000°C
24
Which of the following represents the allotropic forms of iron__________________?
Aalpha iron, beta iron and gamma iron
Balpha iron and beta iron
Cbody centred cubic a-iron and face centred cubic a-iron
Dalpha iron, gamma from and delta iron E. none of the above
25
Malleable cast iron _________________?
Acontains l.7 to 3.5% carbon in free state and is obtained by the slow cooling of molten cast iron
Bis also known as chilled cast iron and is obtained by cooling rapidly. It is almost unmachinable
Cis produced by annealing process. It is soft, tough, and easily machined metal
Dis 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 E. none of the above
26
Tungsten in steel________________?
Aimproves wear resistance, cutting ability and toughness
Brefines grain size and produces less tendency to carburisation, improves corrosion and heat resistant properties
Cimproves cutting ability and reduces hardenability
Dgives ductility, toughness, tensile strength and anticorrosion properties E. raises its melting point
27
Which of the following is not the correct method of increasing fatigue limit __________________?
Ashot peening
Bnitriding of surface
Ccold working
Dsurface decarburisation E. under-stressing
28
Which of the following pipes is least corrosion resistant__________________?
Abrass
Bmild steel
Ccast iron
Dwrought iron E. copper
29
High carbon steel carries carbon %age c_________________?
A0.1 to 0.3%
B0.3 to 0.6%
C0.6 to 0.8%
D0.8 to 1.5% E. 1.5 to 2.5%.
30
The percentage of carbon in low carbon steel is__________________?
A0.05%
B0.15%
C0.3%
D0.5% E. 0.7%.