MCQ
641. The percentage of carbon in pig iron varies from--
0.1 to 12%
2.5 to 4.5%
1.5 to 2.5%
4 to 4.5%
642. Which of the following element results in presence of free graphite in CI--
carbon
silicon
sulphur
manganese
643. Pearlite is a combination of--
ferrite and cementite
cementite and gamma iron
ferrite and austenite
ferrite and iron graphite
644. The cutting tools are made from--
nickel steel
silicon steel
chrome steel
high speed steel
645. Surveying tapes are made of a material having low coefficient of expansion and enough strength. The alloy used is—
silver metal
duralumin
Hastelloy
Invar
646. In which forging is possible without any problem?
alloy steel
low carbon
high carbon
cast
647. Copper when alloyed with zinc is known as--
Brass
Babbits
Bronze
All of the above
648. Which of the following iron exists between Type equation here.910°C and 1403°C?
∝-iron
δ -iron
β-iron
γ-iron
649. The machinability of steel is increased by--
silicon and sulphur
phosphorous, lead and sulphur
sulphur, graphite and aluminium
phosphorous and aluminium
650. The toughness of a material --when it is heated.
increases
remain same
decrease
none
651. The percentage of carbon in grey iron castings usually varies between-
0.5 to 1%
2.5 to 4.5%
1 to 2%
5 to 7%
652. Brass contains--
70% copper and 30% zinc
90% copper and 10% tin
85-92% copper and rest tin with little lead and nickel
70-75% copper and rest tin
653. Tensile strength of steel can be safely increased by--
adding carbon up to 2.8%
adding carbon up to 6.3%
adding carbon up to 0.83%
adding small quantities of copper
654. Vanadium in high speed steels--
promotes decarburisation
provides high hot hardness
forms very hard carbides and thus increases wear resistance
promotes retention of austenite
655. Discontinous chips are formed during machining of--
brittle metal
hard metal
ductile metal
soft metal
656. Lead is poured into the joint between two pipes. These pipes may be made of--
cast iron
asbestos cement
vitrified clay
concrete
657. Which of the following material has maximum ductility?
Mild steel
Nickel
Copper
Aluminum
658. The lower critical point for all steels is—
600°C
700°C
723°C
913°C
659. Recrystallisation temperature can belowered by--
purification of metal
grain refinement
working at lower temperature
all of the above
660. The most effective inhibitor of grain growth. when added in small quantities is--
carbon
manganese
vanadium
Cobalt