L9 - Steel Phase Diagrams Flashcards
1
Q
What is the crystallographic structure of Austenite?
A
- FCC
- Carbon in interstitial sites
2
Q
What is the crystallographic structure of Ferrite?
A
- BCC
- Carbon in interstitial sites
3
Q
What is Austenite?
A
- solid solution of carbon in iron
- is stable at high temperatures
4
Q
What is Ferrite?
A
- solid solution of carbon in iron
- is stable at low temperatures
5
Q
What is cémentite?
A
- Fe3C
- fixed composition
- hard brittle phase
6
Q
What is pearlite?
A
- a microconstituent of Ferrite and Cementite
- eutectoid mixture
- lamellar structure
7
Q
What is a phase?
A
- homogenous region that has uniform physical and chemical characteristics
8
Q
What is a micro constituent?
A
- identifiable element of microstructure
- can contain more than one phase
9
Q
What is a eutectic reaction?
A
- liquid goes to two solids
10
Q
What is a eutectoid reaction?
A
- solid goes to 2 different solids
11
Q
What effect does increasing the amount of Carbon in the composition of steel do?
A
- only Ferrite formed up to 0.022wt%
- is soft and ductile
- only pearlite formed at 0.76wt%
- many phase boundaries, act as grain boundaries
- cementite obstructs dislocation motion
- higher yield stress
- cementite formed at higher carbon concentrations
- increased strength and hardness, however is brittle
- low percentage elongation
