Engineering Materials MCQ Questions & Answers | Mechanical Engineering

Case Hardening, is a heat treatment process that produces a surface which is resistant to wear, while maintaining toughness and strength of the core.
This treatment is applied to low carbon steel parts after machining, as well as high alloy steel bearings, gears, and other components.

The low-melting-point metals such as bismuth, lead, tin, and cadmium are added to aluminum to make free-machining alloys.
lead is added at about the 0.5% level with the same amount as bismuth in some alloys to improve machinability.

Manganese is used to
Increases hardenability, ductility and wear resistance.
Eliminates formation of harmful iron sulphides.
Austenite stabilizer.

This following elements have face-centered cubic structure:
Gamma iron (910°C to 1400°C), Cu, Ag, Au, Al, Ni, Pb, Pt.

The crystal structure of brass is F.C.C.
Face-centered cubic (fcc or cF) refers to a crystal structure consisting of an atom at each cube corner and an atom in the center of each cube face.

Titanium alloys is used to control grain size growth, which improves toughness. Also transforms sulfide inclusions form elongated to globular, improving strength and corrosion resistance as well as toughness and ductility.
Titanium alloys is a very strong, very lightweight metal that can be used alone or alloyed with steels. It is added to steel to give them high strength at high temperatures. Modern jet engines used titanium steels.

Pig Iron is the iron obtained from the blast furnace.
The content of iron in pig iron is very high,
it is around 92% and the second largest composition of pig iron is carbon which is around 4%.

Shock resistance of steel is increased by adding Nickel and chromium

Chromium is a powerful alloying element in steel.
It strongly increases the hardenability of steel, and markedly improves the corrosion resistance of alloys in oxidizing media.
Nickel is added to steels to increase hardenability.

Cobalt in steel Improves cutting ability and reduce hardenability