MCQ
641. 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%
642. The most effective inhibitor of grain growth. when added in small quantities is--
carbon
manganese
vanadium
Cobalt
643. The lower critical point for all steels is—
600°C
700°C
723°C
913°C
644. The toughness of a material --when it is heated.
increases
remain same
decrease
none
645. Pearlite is a combination of--
ferrite and cementite
cementite and gamma iron
ferrite and austenite
ferrite and iron graphite
646. The machinability of steel is increased by--
silicon and sulphur
phosphorous, lead and sulphur
sulphur, graphite and aluminium
phosphorous and aluminium
647. 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
648. The cutting tools are made from--
nickel steel
silicon steel
chrome steel
high speed steel
649. Which of the following element results in presence of free graphite in CI--
carbon
silicon
sulphur
manganese
650. Lead is poured into the joint between two pipes. These pipes may be made of--
cast iron
asbestos cement
vitrified clay
concrete
651. Which of the following iron exists between Type equation here.910°C and 1403°C?
∝-iron
δ -iron
β-iron
γ-iron
652. In which forging is possible without any problem?
alloy steel
low carbon
high carbon
cast
653. Copper when alloyed with zinc is known as--
Brass
Babbits
Bronze
All of the above
654. Recrystallisation temperature can belowered by--
purification of metal
grain refinement
working at lower temperature
all of the above
655. Which of the following material has maximum ductility?
Mild steel
Nickel
Copper
Aluminum
656. Basic constituents of Monel metal are--
nickel, copper
nickel, molybdenum
zinc, tin, lead
nickel, lead and tin
657. 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%
658. Surveying tapes are made of a material having low coefficient of expansion and enough strength. The alloy used is—
silver metal
duralumin
Hastelloy
Invar
659. 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
660. Discontinous chips are formed during machining of--
brittle metal
hard metal
ductile metal
soft metal