1. The work to which we have set ourselves is the liberation of the imagination, and the harnessing of the imagination to man’s physical creativity
- Friedre Ginaz

2. Hardness
Resistance to indentation

3. Hardness
Resistance to indentation
Greater hardness
gives higher
hardness nos.

4. Types of hardness tests

5. Comparison of hardness scales

6. Example - quenched plain carbon steels

7. Correlation betwn strength & hardness
Harder means stronger for metals & alloys

8. Toughness
Resistance to being clobbered

9. Toughness
Resistance to being clobbered
Impact test measures energy absorbed upon fracture
measure of toughness

10. Toughness
Resistance to being clobbered

11. Impact test
measure impact energy at different
temperatures

12. Impact test
measure impact energy at different
temperatures

13. Impact test
measure impact energy at different
temperatures

14. Fracture toughness - KIc = Yc a
resistance to brittle fracture in presence of
a crack - resistance to crack propagation
under load
common specimen configuration
usually pre-cracked here before testing

15. Creep
deformation under small loads at
elevated temps.

16. Fatigue
deformation under small cyclic loads

17. Fatigue
S-N curves & endurance limit

18. Assignments for next class:
1. review today's classnotes; know hardness
tests; impact test & temperature effect:
3 stages of creep; S-N curves
2. Read text: pp , sections , pp