With steel we talked about the five phases of steel from the

With steel, we talked about the five phases of steel from the TTT diagram What are they? Which is the most brittle? Which is the hardest? Which takes the longest time to cool? Which phase(s) are at equilibrium? 5

Solution

The values will depend on the temperature of interest

Normally: CEMENTITE is brittle

MARTENSITE is hard

Longest time to form ( from TTT curve) Bainite

Martensite is not an equilibrium phase

Austenite,Pearlite in equilibrium, Pearlite transforms to a finer orm called Bainite

Martensite is a diffusionless tranformation hence not shown in the equilibrium phase diagram.