What is the first stage in the solidification process of metal?

• Solidification is complete

• Cluster of nucleus form

• Small dendrites begin to develop

• Spaces between dendrites fill

What is the temperature below which a substance is stable in the solid state called?

• Eutectoid

• Critical temperature

• Liquidus

• Solidus

Which phase diagram shows the connection between the amount of carbon and the changes in internal structure of iron and steels?

• Binary phase diagram

• Iron-Carbon phase diagram

• Isomorphous system

• Eutectic phase diagram

What is the maximum carbon solubility in α-ferrite at 727°C?

• 6.67%

• 0.022%

• 0.09%

• 2.14%

What structure does austenite have?

• Face-centered cubic (FCC)

• Hexagonal close-packed (HCP)

• Body-centered cubic (BCC)

• Simple cubic

What is the eutectoid composition for ferrite and cementite?

• 0.9% carbon

• 0.5% carbon

• 1.2% carbon

• 0.76% carbon

What happens to austenite when cooled rapidly?

• It transforms into ferrite

• It turns into cementite

• It transforms into martensite

• It remains unchanged

What is cementite also known as?

• Fe4C

• FeO

• Fe3C

• Fe2O3

What is the stable form of iron at room temperature?

• Austenite

• Martensite

• Ferrite

• Cementite

What is the effect of adding chromium to steel?

• Decreases hardness

• Increases ductility

• Increases resistance to corrosion

• Lowers tensile strength