Engineering Materials — Part 2 MCQs with Explanations

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.

The transistor is made of Germanium

The portion of the blast furnace below its widest cross-section is called Bosh

The silicon steel is widely used for Generators and transformers in the form of laminated cores

Generally rod are made of steel because of ability to absorb high impact at the expense of durability and also for lightness of steel.

Blast furnace is used to produce Pig iron

Compressive strength of grey cast iron is 57 tonnes/cm

Y-alloy contains 3.5 to 4.5% copper, 1.2 to 1.7% manganese, 1.8 to 2.3% nickel, 0.6% each of silicon, magnesium and iron, and rest aluminium

Wrought iron is an iron alloy with very low carbon content with respect to cast iron. It is soft, ductile, magnetic, and has high elasticity and tensile strength. It can be heated and reheated and worked into various shapes.

White cast iron Is also known as chilled cast iron and is obtained by cooling rapidly. It is almost unmachinable. White cast iron is a cast iron without any alloy addition and with low C and Si content such that the structure is hard brittle iron carbide with no free graphite. A fast cooling rate prevents the precipitation of C as graphite.

When the steel is normalized, its Yield point increases, Ductility decreases and Ultimate tensile strength increases.

Amorphous material is one In which there is no definite atomic structure and atoms exist in a random pattern just as in a liquid

Cast iron is manufactured in Cupola

The molecules in a solid move Back and forth like tiny pendulums

Upper bainite is a microstructure in steel that forms at higher transformation temperatures compared to lower bainite, typically in the range of 350°C to 550°C. It has an acicular structure consisting of parallel ferrite plates separated by cementite, giving it a distinctive needle-like appearance. Because it forms at higher temperatures, carbon diffusion is more pronounced, leading to coarser carbide particles and lower hardness compared to lower bainite. On the Rockwell C (RC) scale , upper bainite typically measures around RC 48 , which is lower than the hardness of lower bainite (around RC 57) and much lower than untempered martensite (around RC 65 or higher). This hardness level offers moderate strength with better toughness than harder microstructures.

A reversible change in the atomic structure of the steel with a corresponding change in the properties is known as Allotropic change

A reversible change in the atomic structure of steel with corresponding change in the properties is known as Allotropic change

Hardness of martensite is about RC 65

A coarse grained steel is less tough and has a greater tendency to distort during heat treatment

Wrought iron is least corrosion resistant

Points of arrest for iron correspond to Stages at which allotropic forms change

The charge is fed into the blast furnace through the Throat

The charge of the blast furnace consists of Calcined ore (8 parts), coke (4 parts) and limestone (1 part)

Pearlite consists of 13% cementite and 87% ferrite

Balls for ball bearings are made of Carbon-chrome steel

resilience is the ability of a material to absorb energy when it is deformed elastically, and release that energy upon unloading.

grey cast iron is a type of cast iron that has a graphitic microstructure

Gas turbine blade is made up of exotic materials superalloys to withstand in the difficult environment inside the gas turbine. As a consequence of operating the gas turbine at high temperature and high stresses, the turbine blades are subjected to certain deformation (creep).

Iron-carbon alloys containing 1.7 to 4.3% carbon are known as Hypoeutectic cast irons

The correct answer is A: Cold rolled steel . Let's break down why: Cold rolled steel: This type of steel is processed at room temperature after hot rolling. This process increases its strength, improves its surface finish, and makes it more dimensionally accurate. These are all important properties for bicycle frames, which need to be strong, lightweight, and have a smooth finish for welding and painting. Hot rolled steel: This steel is processed at high temperatures. While it's cheaper to produce, it's not as strong or dimensionally accurate as cold-rolled steel. Its surface finish is also rougher, making it less suitable for bicycle frames. Forged steel: Forging involves shaping steel using compressive forces. While forging can produce very strong parts, it's more commonly used for components like crankshafts or connecting rods that need to withstand extreme stress, not entire frame tubing. Cast steel: Casting involves pouring molten steel into a mold. Cast steel can be used to make complex shapes, but it generally has lower strength and ductility compared to wrought steels (like rolled or forged steel). It is rarely used for bicycle frames due to its weight and potential for porosity. In Summary: Bicycle frames need a strong, lightweight material with a good surface finish. Cold rolled steel provides the best balance of these properties, making it the ideal choice for bicycle frame tubing.

Uranium, Thorium and Niobium metal are used for nuclear energy

Aluminium bronze contains aluminium and copper in the ratio of 10 : 90

phosphor bronze is an alloy of copper with 0.5–11% of tin and 0.01–0.35% phosphorus

A material is known as allotropic or polymorphic if it Exists in several crystal forms at different temperatures