1. The American University in Cairo Mechanical Engineering Department MENG 426: Metals, Alloys & Composites Interactive MENG 426 Lab Tutorials Experiment (4) Eutectoid, Hyper- & Hypo- Alloys Prepared by Eng. Moataz M. Attallah Fall 2002

2. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab ReportsOutline 1.Review: phase diagrams & invariant reactions 2.Fe-Fe 3 C System: major features 3.Eutectoid reaction 4.Controlling parameters 5.Specimens 6.Lab report

3. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Review: Phase diagrams   Phase Diagram: Graphical representation for the material (pure/mixture/binary alloy/tertiary alloy) within a temperature range at a range of compositions, showing the existing phases & any transformation reactions. Equilibrium Diagrams Equilibrium cooling: slow cooling that does not deform the structure.

4. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Review: Invariant reactions   Phase transformation reactions that take place at a specific temperature and composition (zero degree of freedom).   Types: Eutectic Eutectoid Peritectic Peritectoid Montectic

5. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Fe-Fe 3 C System Iron-Iron Carbide System

6. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Fe-Fe 3 C System phases (1) Iron-Iron Carbide System Fe 3 C Cementite or Iron Carbide 6.67% C, 93.33% Fe Stoichiometric Intermetallic Ionic & covalent bonding Hard and brittle

7. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Fe-Fe 3 C System phases (2) Iron-Iron Carbide System http://info.lu.farmingdale.edu/depts/met Austenite Gamma iron, FCC, ISS Maximum solubility 2%

8. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Fe-Fe 3 C System phases (3) Iron-Iron Carbide System http://info.lu.farmingdale.edu/depts/met Ferrite Alpha iron, BCC, ISS Maximum solubility 0.02%

9. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Fe-Fe 3 C System phases (4) Iron-Iron Carbide System Delta Ferrite Alpha iron, BCC, ISS Maximum solubility 0.1%

10. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Fe-Fe 3 C System phases (5) Iron-Iron Carbide System Ledeburite Eutectic (Fe 3 C+ ) Cast iron eutectic

11. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Eutectoid Reaction Pearlite

12. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Eutectoid Microstructure

13. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab ReportsHypo/Eutectoid/Hyper

14. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Hyper- & Hypo-Eutectoid

15. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Hypo- & Hyper- Eutectoid

16. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab ReportsObjective  Get acquainted with Fe-Fe 3 C phase diagram.  Study the effect of the eutectoid invariant reaction on steel microstructure.  Differentiate between eutectoid, hypo-eutectoid, and hyper-eutectoid microstructures.  Study the effect of cooling on microstructure

17. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab ReportsSpecimens Specimen (1): 0.35%C, etched for 15 sec. in 2% HNO 3 alchoholic solution (nital) Specimen (2): 0.8% C, furnace cooled, ground and polished with diamond paste and finishing with a 1 micron grade, followed by etching with nital. Specimen (3): same as specimen (2), with air- cooling Specimen (4): 1.3%C etched in nital

18. Review Phase diagram Invariant re-ax Fe-Fe 3 C system Phases Eutectoid Re-ax Microstructure Hypo- & Hyper- Specimens Lab Reports Lab Report Required:  A "neat" sketch for the viewed microstructures.  Describe the phase transformation for each specimen from the liquid state to the solid state with the aid of the (Fe-Fe 3 C) phase diagram.

19. Questions?