Engineering Materials MCQ Questions & Answers | Mechanical Engineering

When elements like nickel, chromium, copper and molybdenum are added to the molten cast iron, it produces Alloy cast iron.
Alloy cast iron - cast iron containing alloying elements (usually nickel or chromium or copper or molybdenum) to increase the strength or facilitate heat treatment.
Alloy cast iron - an alloy of iron containing so much carbon that it is brittle and so cannot be wrought but must be shaped by casting.

Ferromagnetism refers to materials (such as iron and nickel) that can retain their magnetic properties when the magnetic field is removed.

Corundum is a crystalline form of aluminium oxide (Al₂O₃) typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral.

When steels with exactly 0.8% carbon (known as a eutectoid steel), are cooled, the austenitic phase (FCC) of the mixture attempts to revert to the ferrite phase (BCC).
There is only one critical point in eutectoid steel which contains 0.8% carbon.

Age hardening is a heat treatment technique used to increase the yield strength of malleable materials, including most structural alloys of aluminium, magnesium, nickel, titanium and some steels and stainless steels.
Age hardening is related to Duralumin.

Inconel contains 80% nickel, 14% chromium and 6% iron

Correct Answer: B) It brittle

Pig iron is the raw material used to make steel.

Sulphur is an impurity that can be found in pig iron.

When too much sulphur is present, it makes the iron brittle, meaning it's more likely to crack or break when bent or stressed.

Let's look at why the other options are not the best answer:

A) It easily machinable: Sulphur can *sometimes* improve machinability in steel, but it usually doesn't in pig iron, and excessive sulphur makes it brittle not machinable.

C) It hard: While sulphur can affect hardness, its primary effect is to make the iron brittle.

D) The casting unsound: While high sulphur content *can* contribute to casting defects, the primary effect is that the resulting iron will be brittle even if the casting is good otherwise. Therefore, brittle is the better answer as this directly relates to the material's property.

So, the presence of sulphur in pig iron primarily makes it brittle.

There are fourteen atoms in a unit cell of Face centered cubic space lattice

There are some properties of aluminium is listed below:
Low density
Simple to process
Smooth surface
Lower dimensional tolerances
Not magnetisable
Can be decoratively anodised very well (dependent on the alloy)
Good machinability (dependent on the strength and alloying elements)

Sometimes referred to as yellow brass, has a nominal composition of 70% copper and 30% zinc.
Cartridge brass can be cold rolled into sheets, drawn into wires and formed into tube.