Phase diagrams QCAA Engineering Unit 4

What does the knowledge of phase diagrams allow engineers to achieve in steel?

• Desired mechanical properties

• Desired colour

• Desired weight

• Desired cost

What is the temperature at which austenite (γ) transforms into ferrite (α) in the Fe-C phase diagram?

• 727°C

• 912°C

• 1147°C

• 1394°C

Which phase is labeled as "α" in the Fe-C phase diagram?

• Austenite

• Ferrite

• Cementite

• Liquid

What is the softest structure in the iron-carbon alloy system?

• Austenite

• Cementite

• Pearlite

• Ferrite

What is the form of a eutectic reaction in the iron-carbon phase diagram?

• Liquid solution ⇌ Ferrite + Cementite

• Liquid solution ⇌ Austenite + Cementite

• Liquid solution ⇌ Ferrite + Austenite

• Liquid solution ⇌ Pearlite + Cementite

What phases are involved in the eutectoid reaction in the iron-carbon alloy system?

• A) Liquid and Austenite

• B) Ferrite and Cementite

• C) Austenite and Liquid

• D) Ferrite and Liquid

What is the eutectoid microconstituent of ferrite and cementite called?

• Austenite

• Martensite

• Pearlite

• Bainite

What is the carbon content range for steels?

• Less than 0.008 wt% C

• 0.008 to 2.14 wt% C

• Greater than 2.14 wt% C to 6.67 wt% C

• 1.00 to 3.00 wt% C

What is the carbon content of irons?

• Less than 0.008 wt% C

• 0.008 to 2.14 wt% C

• Greater than 2.14 wt% C to 6.67 wt% C

• 1.00 to 3.00 wt% C

At what temperature do iron-carbon alloys with 0.76 wt % C pass through the eutectoid point?

• 727°C

• 727°F

• 927°C

• 927°F