Engineering Materials MCQ Questions & Answers | Mechanical Engineering

Blackheart cast iron. and Whiteheart cast iron has similar properties to steel

When low carbon steel is heated up to upper critical temperature, the average grain size is a minimum.

When low carbon steel is heated up to lower critical temperature There is no change in grain size

The lower critical temperature is same for all steels.
Lower critical temperature for steel’s austenite-to-pearlite transformation is 1333°Fahrenheit (723°Celsius). Below this temperature, austentite doesn’t exist.

Below 773°C (1,423°F), alpha iron becomes ferromagnetic (i.e., capable of being permanently magnetized), indicating a change in electronic structure but no change in crystal structure.

1.The unit cells Contain the smallest number of atoms which when taken together have all the properties of the crystals of the particular metal
2. The unit cells Have the same orientation and their similar faces are parallel
3. The unit cells May be defined as the smallest parallelepiped which could be transposed in three coordinate directions to build up the space lattice

Pig iron is the intermediate product extracted from iron ore in a blast furnace.
Pig iron is used as raw material in steel making.
Pig iron gets its name from the old fashioned method of casting the iron into moulds arranged in sand beds so that they could be fed from a common runner

Silicon is an impurity in cast iron that promotes the formation of graphite nodules.

It also increases the fluidity of the molten metal, making it easier to cast.

Option B: Sulphur is incorrect because sulphur generally promotes the formation of iron sulfide, which is detrimental to the properties of cast iron.

Option C: Manganese is incorrect because manganese is used to counteract the effects of sulphur but does not promote graphite nodule formation.

Option D: Phosphorus is incorrect because while phosphorus can increase fluidity, it does not specifically promote graphite nodule formation like silicon does.


Conclusion:

Silicon in cast iron promotes graphite nodule formation and increases the fluidity of the molten metal.

Wrought iron is soft, ductile, magnetic, and has high elasticity and tensile strength. It can be heated and reheated and worked into various shapes.

Nichrome is a nickel-chromium alloy with non-magnetic properties.