76. Cyaniding is the process of
(a) dipping steel in cyanide bath
(b) reacting steel surface with cyanide salts
(c) adding carbon and nitrogen by heat treatment of steel to increase its surface hardness
(d) obtaining cyanide salts
(e) making corrosion resistant steel.
Ans: c
77. Induction hardening is the process of
(a) hardening surface of workpiece to obtain hard and wear resistant surface
(b) heating and cooling rapidly
(c) increasing hardness throughout
(d) inducing hardness by continuous process
(e) hardening core.
Ans: a
78. The loss of strength in compression with simultaneous gain in strength in tension due to overloading is known as
(a) hysteresis
(b) creep
(c) visco elasticity
(d) Boeschinger effect
(e) inelasticity.
Ans: d
79. Process of austempering results in
(a) formation of bainite structure
(b) carburised structure
(c) martenistic structure
(d) lamellar layers of carbide distributed throughout the structure
(e) relieving of stresses throughout a component.
Ans: a
80. The surface hardness of the following order is achieved by nit riding operation
(a) 600 VPN
(b) 1500 VPN
(c) 1000 to 1100 VPN
(d) 250 VPN
(e) 2000 VPN.
Ans: c
81. Hardness of martensite is about
(a) RC 65
(b) RC 48
(c) RC 57
(d) RC 80
(e) RC 32.
Ans: a
82. Weld decay is the phenomenon found with
(a) cast iron
(b) mild steel
(c) non-ferrous materials
(d) wrought iron
(e) stainless steel.
Ans: e
83. Materials after cold working are subjected to following process to relieve stresses
(a) hot working
(b) tempering
(c) normalising
(d) annealing
(e) special heat treatment.
Ans: d
84. Hardness of upper bainite (acicular structure) is about
(a) RC 65
(b) RC 48
(c) RC 57
(d) RC 80
(e) RC 32.
Ans: b
85. Carbon in iron is an example of
(a) substitutional solution
(b) interstitial solid solution
(c) intermetallic compounds
(d) all of the above
(e) none of the above.
Ans: b
86. Brass (alloy of copper and zinc) is an example of
(a) substitutional solid solution
(b) interstitial solid solution
(c) intermetallic compounds
(d) all of the above
(e) none of the above.
Ans: a
87. Which is false statement about annealing.
Annealing is done to
(a) relieve stresses
(b) harden steel slightly
(c) improve machining characteristic
(d) soften material
(e) permit further cold working.
Ans: b
88. Argentite is the principal ore or raw material for
(a) aluminium
(b) tin
(c) zinc
(e) lead
(e) silver.
Ans: e
89. Hardness of lower bainite (tempered martensite) is about
(a) RC 65
(b) RC 48
(c) RC 57
(d) RC 80
(e) RC 32.
Ans: c
90. Which is false statement about normalising. Normalising is done to
(a) refine grain structure
(b) reduce segregation in casting
(c) improve mechanical properties
(d) induce stresses-
(e) relieve internal stresses.
Ans: d
91. Vanadium in high speed steels
(a) promotes decarburisation
(b) provides high hot hardness
(c) forms very hard carbides and thus in-creases wear resistance
(d) promotes retention of austenite
(e) increases toughness.
Ans: c
92. Amorphous material is one
(a) in which atoms align themselves in a geometric pattern upon solidification
(b) in which there is no definite atomic structure and atoms exist in a random pattern just as in a liquid
(c) which is not attacked by phosphorous
(d) which emits fumes on melting
(e) none of the above.
Ans: b
93. Dislocations in materials refer to the following type of defect
(a) point defect
(b) line defect
(c) plane defect
(d) volumetric defect
(e) chemical defect.
Ans: b
94. An example of amorphous material is
(a) zinc
(b) lead
(c) silver
(d) glass
(e) brass.
Ans: d
95. Which is false statement about tempering.
Tempering is done to
(a) improve machinability
(b) improve ductility
(c) improve toughness
(d) release stresses
(e) reduce hardness and brittleness.
Ans: a
96. Which is false statement about case hardening. Case hardening is done by
(a) electroplating
(b) cyaniding
(c) induction hardening
(d) nitriding
(e) flame hardening.
Ans: a
97. Which of the following is the binding material in cemented carbides
(a) cobalt
(b) nickel
(c) vanadium
(d) iron
(e) carbon.
Ans: a
98. Chromium in steel
(a) improves wear resistance, cutting ability and toughness
(b) refines grain size and produces less tendency to carburisation, improves corrosion and heat resistant properties
(c) improves cutting ability and reduces hardenability
(d) gives ductility, toughness, tensile strength and anticorrosion properties
(e) makes steel hard.
Ans: a
99. Manganese in steel increases its
(a) tensile strength
(b) hardness
(c) ductility
(d) fluidity
(e) malleability.
Ans: a
100. Cemented carbide tools are nqt found to be suitable for cutting
(a) brass
(b) cast iron
(c) aluminium
(d) steel
(e) non-ferrous alloys.
Ans: d