Engineering Materials MCQ Questions & Answers | Mechanical Engineering

Stainless steel is an alloy of Iron with a minimum of 10.5% Chromium.
Chromium produces a thin layer of oxide on the surface of the steel known as the 'passive layer'.
This prevents any further corrosion of the surface.
Increasing the amount of Chromium gives an increased resistance to corrosion.

The Bauschinger effect refers to a property of materials where the material's stress/strain characteristics change as a result of the microscopic stress distribution of the material.
For example, an increase in tensile yield strength occurs at the expense of compressive yield strength

The Bessemer process is an industrial process for the mass production of steel from molten pig iron before the development of the open hearth furnace.
The key principle is removal of impurities from the iron by oxidation with air being blown through the molten iron.
In basic Bessemer process, the furnace is lined with a mixture of tar and burnt dolomite bricks.

Babbitt metal is a soft alloy of tin.
Babbitt metal contains 89.3% tin, 7.1% antimony and 3.6% copper.

Gamma iron is an allotropic form of iron existing between the temperature 910°C and 1400°C and having a face-centered cubic lattice.
It is a metallic, non-magnetic allotrope of iron or a solid solution of iron with an alloying element.

Induction hardening is a type of surface hardening in which a metal part is induction-heated and then quenched.
The quenched metal undergoes a martensitic transformation, increasing the hardness and brittleness of the part.
In induction hardening Frequency is high.

S. G. Iron (Spheroidal Graphite Iron) is a type of cast iron that has been treated while molten with an element such as magnesium or cerium to induce the formation of free graphite as nodules or spherulites. This imparts a measurable degree of ductility (easily manipulated) to the cast metal.
According to Indian standard specifications, SG 400/15 means Spheroidal graphite cast iron with minimum tensile strength 400 MPa and 15 percent elongation.

gun metal contains lead in addition to the zinc; it is typically composed of 86% copper, 9.5% tin, 2.5% lead, and 2% zinc.

Below 912°C (1,674°F) iron again adopts the BCC structure characteristic of α-iron, also called ferrite. The substance assumes a paramagnetic property and it changes into gamma iron.

iron with a bcc structure is called ferrite. Another name for ferrite is alpha iron.
ferrite is shown in figure