Engineering Materials MCQ Questions & Answers | Mechanical Engineering

Heat treatment process effect on material structure and grains.
Most carbon steels and carbon alloy steels can be heat treated for the purpose of improving mechanical properties such as tensile and yield strength.
This is accomplished due to the heat treatment fundamentally altering the microstructure of the steel.

The tensile strength of wrought iron is maximum. Along the lines of slag distribution

sulfur is normally regarded as an impurity and has an adverse effect on impact properties when a steel is high in sulphur and low in manganese.
Sulphur improves machinability but lowers transverse ductility and notched impact toughness and has little effects on the longitudinal mechanical properties

Connecting rod is, usually, made from Medium carbon steel

Ball bearings are usually made from Chrome steel

A small percentage of boron is added to steel in order to Increase hardenability

Steel is primarily an alloy of iron and carbon, with iron being the major component.

By definition, steel contains more than 80% iron, and the rest is mainly carbon (usually less than 2%) along with small amounts of other elements.

Option A is correct because it directly reflects the high percentage of iron in steel, which typically exceeds 80% in composition.

Option B is incorrect as 50% is too low to define steel; that would categorize it as a different alloy.

Option C mentions alloying elements which are used in special steels (like stainless steel), but they are present in much smaller proportions and are not defining features of all steels.

Option D lists impurities or residual elements often found in steel, but they are not the primary constituents.

Therefore, the correct answer is Option A: 80% or more iron

The steels which contains less than 0.8% carbon are known as hypo eutectoid steels. It consists of pearlite and proeutectoid ferrite.

Brass is an alloy of Copper and zinc

The transistor is made of Germanium