126. Pipes for bicycle frames are made of
(a) cold rolled steel
(b) hot rolled steel
(c) forged steel
(d) cast steel
(e) carbon-chrome steel.
Ans: a
127. Large forgings, crank shafts, axles normally contain carbon upto
(a) 0.05 to 0.20%
(b) 0.20 to 0.45%
(c) 0.45 to 0.55%
(d) 0.55 to 1.0%
(e) 1.0 to 1.2%.
Ans: c
128. Heavy duty leaf and coil spring* contain carbon of the following order
(a) 0.2%
(b) 0.5%
(c) 0.8%
(d) 1.0%
(e) 1.5%.
Ans: d
129. Taps, dies and drills contain carbon
(a) below 0.5%
(b) below 1%
(c) above 1%
(d) above 2.2%
(e) nil.
Ans: c
130. Drop forging dies contain carbon of the order of
(a) 0.1 to 0.2%
(b) 0.25 to 0.5%
(c) 0.6 to 0.7%
(d) 0.7 to 0.9%
(e) 1.0 to 1.2%.
Ans: c
131. Which is the false statement about wrought iron. It has
(a) high resistance to rusting and cor¬rosion
(b) high ductility
(c) ability of hold protective coating
(d) easily weldable characteristics
(e) uniform strength in all directions.
Ans: e
132. The tensile strength of wrought iron is maximum
(a) along the lines of slag distribution
(b) perpendicular to lines of slag dis-tribution
(c) uniform in all directions
(d) unpredictable
(e) none of the above.
Ans: a
133. Balls for ball bearings are made of
(a) cast iron
(b) mild steel
(c) stainless steel
(d) carbon-chrome steel
(e) high carbon steel.
Ans: d
134. Malleable cast iron
(a) contains lv7 to 3.5% carbon in free state and is obtained by the slow cooling of molten cast iron
(b) is also known as chilled cast iron and is obtained by cooling rapidly. It is almost unmachinable
(c) is produced by annealing process. It is soft, tough, and easily machined metal
(d) is 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.
Ans: c
135. Preheating is essential in welding
(a) cast iron
(b) high speed steel
(c) all non-ferrous materials
(d) all of the above
(e) none of the above.
Ans: a
136. The hardness of steel primarily depends on
(a) %age of carbon
(b) %age of alloying elements
(c) heat treatment employed
(d) method of manufacture
(e) shape of carbides and their distribution in iron.
Ans: e
137. Steel made from phosphatic iron is
(a) brittle
(b) hard
(c) ductile
(d) tough
(e) malleable.
Ans: a
138. Ductile cast iron
(a) contains 1.7 to 3.5% carbon in free state and is obtained by the slow cooling of molten cast iron
(b) is also known as chilled cast iron and is obtained by cooling rapidly. It is almost unmachinable
(c) is produced by annealing process. It is soft, tough and easily machined metal
(d) is produced by small additions of magnesium (or creium) in the ladle. Graphite is in nodular or spheroidal form and is well dispersed throughout the material
(e) none of the above.
Ans: d
139. Brass contains
(a) 70% copper and 30% zinc
(b) 90% copper and 10% tin
(c) 85-92% copper and rest tin with little lead and nickel
(d) 70-75% copper and rest tin
(e) 70% copper and 30% tin.
Ans: a
140. The crystal structure of brass is
(a) F.C.C.
(b) B.C.C.
(c) H.C.P.
(d) Orthorhombic crystalline structure
(e) none of the above.
Ans: a
141. The composition of silver solder is
(a) silver, copper, zinc
(b) silver, tin, nickel
(c) silver, lead, zinc
(d) silver, copper, aluminium
(e) silver, lead, tin
Ans: a
142. Which one of the following metals would work-harden more quickly than the others?
(a) copper
(b) brass
(c) lead
(d) silver
(e) aluminium.
Ans: b
143. A specimen of aluminium metal when observed under microscope shows
(a) B.C.C. crystalline structure
(b) F.C.C. crystal structure
(c) H.C.P. structure
(d) a complex cubic structure
(e) orthorhombic crystalline structure.
Ans: b
144. The usual composition of a soldering alloy is
(a) tin, lead and small percentage of an-timony
(b) tin and lead
(c) tin, lead and silver
(d) tin and copper
(e) tin, copper and lead.
Ans: a
145. Admiralty brass used for steam condenser tubes contains copper and zinc in the following ratio
(a) 50 : 50
(b) 30 : 70
(c) 70 : 30
(d) 40 : 60
(e) 60 : 40.
Ans: b
146. Corrosion resistance of steel is increased by adding
(a) chromium and nickel
(b) nickel and molybdenum
(c) aluminium and zinc
(d) tungsten and sulphur
(e) none of the above.
Ans: a
147. Corrundum contains more than 95%
(a) steel
(b) A1203
(c) Si02
(d) MgO
(e) german silver.
Ans: b
148. Alnico, an alloy used extensively for per-manent magnets contains iron, nickel, aluminium and cobalt in the following ratio
(a) 50 : 20 : 20 : 10
(b) 40 : 30 : 20 : 10
(c) 50 : 20 : 10 : 20
(d) 30 : 20 : 30 : 20
(e) 50 : 10 : 20 : 20.
Ans: a
149. If a refractory contains high content of silicon, it means refractory is
(a) acidic
(b) basic
(c) neutral
(d) brittle
(e) none of the above.
Ans: c
150. Bell metal contains
(a) 70% copper and 30% zinc
(b) 90% copper and 10% tin
(c) 85-92% copper and rest tin with little lead and nickel
(d) 70-75% copper and rest tin
(e) 70-75% copper and rest zinc and tin.
Ans: d