Ferrous Alloys 7.3.1

What is Austenite?

• A phase of iron with a BCC structure

• An interstitial solid solution of carbon in FCC iron

• A type of heat treatment process

• A phase found only in non-ferrous metals

What is the main purpose of heat treatment?

• To melt metals for casting

• To remove impurities from metals

• To alter mechanical properties by heating and cooling metals
  

• To mix different metals into an alloy

Which of the following is NOT a common heat treatment method?

• Annealing

• Galvanization

• Hardening

• Tempering

What is the main characteristic of annealing?

• Rapid cooling in water or oil

• Slow cooling to soften the metal
  

• Heating without changing microstructure
  

• Hardening the outer surface only

Why is normalising performed on metals?

• To make them brittle and hard

• To relieve internal stresses and create a uniform grain size

• To increase electrical conductivity

• To dissolve carbon in iron

What is the purpose of tempering?

• To increase hardness and make metal brittle

• To reduce hardness and relieve internal stresses

• To absorb carbon into the surface

• To rapidly cool the metal in oil

Which heat treatment process increases the surface hardness by absorbing carbon?

• Tempering
  

• Ageing

• Carburisation

• Stress relieving

• Nitriding

What is the name of the temperature where iron loses its magnetism?

• Curie temperature

• Melting point

• Austenite point

• Critical Temperature

Which heat treatment method is mainly used to improve the yield strength of metals?

• Annealing

• Stress relieving

• Case hardening

• Precipitation hardening (Ageing)

What percentage of carbon marks the boundary between steel and cast iron in the iron-carbon phase diagram?

• 0.6 %

• 2.14%

• 0.8%

• 1.14