Phase Diagrams - Part 2 Flashcards
What is the quenching process?
The soaking of a metal at high temperatures within the recrystallisation phase, followed by a rapid cooling progress
What does the quenching of steel produce?
Martensite
What is the tempering process?
The steady heating of martensitic steel at temperature below the recrystallisation phase, followed by the cooling phrase
What can be said for the ductility of martensite?
Negligible (most brittle steel microstructure)
What are the outcomes of slow, medium and rapid cooling of Austenite?
Slow - Pearlite
Medium - Bainite
Rapid - Martensite
What has the highest yield strength out of pearlite and martensite?
Martensite
What has the highest hardness out of pearlite and martensite?
Martensite
What has the highest UTS out of pearlite and martensite?
Martensite
What has the highest fracture toughness out of pearlite and martensite?
Pearlite
What effect does tempering martensite do?
- Tempered martensite is less brittle than martensite
- Sacrifices some strength and hardness for increased toughness
- Tempering reduces internal stresses caused by quenching
- Some carbon comes out of solution
What is annealing?
The steady heating of a metal at a certain temperature above the recrystallisation phase followed by a slow cooling process
What is hardenability and what test is used to measure it?
Measure of the ability to form martensite.
Jominy end quench test
What does the microstructure of an alloy depend on?
Its composition and cooling rate
