221. When a low carbon steel is heated upto lower critical temperature,
there is no change in grain size
the average grain size is a minimum
the grain size increases very rapidly
the grain size first i
✅ The correct answer is option A.
Engineering Materials MCQs
222. According to Indian standard specifications, SG 400/15 means
spheroidal graphite cast iron with B.H.N. 400 and minimum tensile strength 15 MPa
spheroidal graphite cast iron with minimum tensile strength 400 MPa and 15 percent elongation
spheroidal graphite cast iron with minimum compressive strength 400 MPa and 15 percent reduction in area
none of the above
✅ The correct answer is option B.
223. Body centred cubic space lattice is found in
zinc, magnesinm, cobalt, cadmium, antimony and bismuth
gamma-iron, aluminium, copper, lead, silver and nickel
alpha-iron, tungsten, chromium and molybdenum
none of the above
✅ The correct answer is option C.
224. In high speed steels, manganese is used to tougher the metal and to increase its
yield point
critical temperature
melting point
hardness
✅ The correct answer is option B.
225. According to Indian standard specifications, a plain carbon steel designated by 40 C8 means that the carbon content is
0.04%
0.35 to 0.45%
0.4 to 0.6%
0.6 to 0.8%
✅ The correct answer is option B.
226. A steel with carbon above 0.8% is known as hyper-eutectoid steel.
Agree
Disagree
✅ The correct answer is option A.
227. Silicon is added in low carbon steels to
make the steel tougher and harder
make the steel of good bending qualities
raise the yield point
all of these
✅ The correct answer is option A.
228. Which of the following solids are malleable and ductile?
Ionic solids
Covalent solids
Metallic solids
none of these
✅ The correct answer is option C.
229. The aluminium alloy made by melting aluminium with 2 to 10% magnesium and 1.75% copper is called
duralumin
Y-alloy
magnalium
hindalium
✅ The correct answer is option C.
230. In the austempering process of heat treatment, austenite changes into
martensite
troostite
sorbite
bainite
✅ The correct answer is option D.