Microstructure of Steels Lesson & Quiz

What is the symbol used to represent Austenite in the microstructure of steels?

• α'

• γ

• α

• θ

Which phase is represented by the symbol α' in the microstructure of steels?

• Martensite

• Pearlite

• Cementite

• Idiomorphic ferrite

According to the text, the iron-carbon equilibrium phase diagram is useful for interpreting microstructures in steels because:

• It shows the transformation behavior of austenite at high temperatures.

• It indicates the aesthetic beauty of microstructures.

• It provides a detailed chemical composition of steel.

• It remains unchanged regardless of the concentration of solutes in the steel.

Tags

NGSS.HS-PS1-3

What is the purpose of identifying the microstructures in steel using simple techniques?

• To appreciate their aesthetic beauty.

• To understand their metallurgical theory.

• To identify the phases that grow from austenite.

• All of the above.

What type of crystal structure does austenite have?

• Orthorhombic unit cell structure

• Hexagonal close-packed structure

• Cubic-close packed crystal structure

• Body-centred cubic structure with an atom at each corner and at the centre of each face

What is the crystal structure of cementite?

• Cubic-close packed crystal structure

• Orthorhombic unit cell containing four formula units of Fe3C

• Hexagonal close-packed structure

• Body-centred cubic structure

Steels with a carbon concentration that exceeds the eutectoid concentration are known as:

• Hypoutectoid

• Hyperutectoid

• Hypereutectoid

• Eutectoid

Tags

NGSS.HS-PS2-6

Which mechanism involves a homogeneous deformation of the parent unit cell to generate the unit cell of ferrite?

• Displacive mechanism

• Reconstructive mechanism

• Diffusive mechanism

• Transformative mechanism

What is the basis of the shape memory effect according to the text?

• Change in the chemical composition during transformation

• One-to-one atomic correspondence between the ferrite and austenite

• The generation of strain energy during transformation

• The accommodation of atoms in a thin-plate shape

At what temperature does the reconstructive mechanism become sluggish?

• Below 850 K

• Above 850 K

• At room temperature

• At 0 K

Tags

NGSS.HS-PS1-5