1. 1545 1 2 3 1.ECTECTIC 2.PERITECTIC 3.EUTECTOID 1537 Cementite Fe 3 C

2. Fe- C diagram- REGIONS HYPOEUTECTOID HYPEREUTECTIC HYPEREUTECTOID STEEL CAST IRON 1131 723 0.8 2 4.3 1545 1537 0.16 1493 6.7 HYPOEUTECTIC

3. Fe- C diagram- simplified R P Q C 100 Fe Austenite+cementite- LEDEBURITE Ferrite + Cementite- PEARLITE MARTENSITE- a metastable phase of steel- by quenching- highly stressed α iron supersaturated with carbon

4. EUTECTIC REACTION EUTECTIC TEMPERATURE LIQUID α+ β

5. Location 1- Eutectic Reaction

6. PERITECTIC REACTION Liquid + β α Peritectic Temperature PERI in Greek- Around

7. Location 2- Peritectic Reaction δ Iron - BCC - γ Iron – FCC - AUSTENITE

8. EUTECTIOD REACTION SOLID 1 SOLIDS 2 & 3 EUTECTIOD TEMPERATURE

9. Location 3- EUTECTOID REACTION 0.8% C FERRITE α +γ γ FERRITE + CEMENTITE δ Iron - BCC – Max. solubility of 0.1% at 1493 0 C γ Iron – FCC – AUSTENITE- max. solubility of 2% at 1131 0 C α Iron – BCC- max. solubility of 0.22% at 723 0 C – FERRITE Fe 3 C –CEMENTITE - 100% iron carbide - Intermetallic Compound - From Latin caementum, meaning stone chips. –

10. 723 0 C 910 0 C

11. Unit cells AusteniteFerriteMartensite FCC BCC RECT.PRISM- BC Tetragonal

12. Effect of carbon % (by weight) on lattice dimensions Fe atom C atom Carbon % c (nm)a (nm) 00.286 0.200.2880.2858 0.400.2910.2856