1. Factors affecting diffusion rates 1.Concentration Gradient—driving force 2.Diffusing species & host material 3.Temperature

2. Diffusing Host MetalT( o C)D (m 2 /s) species Fe  -Fe (BCC)5003.0 x 10 -21 Fe  -Fe (BCC)9001.8 x 10 -15 Fe  -Fe (FCC)5001.1 x 10 -17 Fe  -Fe (FCC)9007.8 x 10 -16 Which diffuses faster? A.Fe through  -Fe at 500 o C B.Fe through  -Fe at 900 o C C.Fe through  -Fe at 500 o C D.Fe through  -Fe at 900 o C

3. How does diffusion affect material properties?

4. Brass = Alloy of Copper and Zinc

5. Bras s Copp er Zinc Brass = Stronger than either Copper or Zinc Explanation in Chapter 7

6. City Steel Heat Treating Co. Solid Diffusion Hardening: Case Hardening  Hard Case w/ tough core Low-C Steels (> 0.30% C): Carburizing, Nitriding, Carbonitriding Carburized depth of 0.030 ” to 0.050 ” in 4 hours @ 1700°F

7. What happens in the case: Steel = C + Fe Add more C to the outer surface. Interstitial C imposes lattice strains in Fe Strains near dislocations can bind atoms and reduce deformation (see Ch. 7)

8. Carburizing—Solid Diffusion process Begin at 1:35–2:40 YouTube: Vacuum Carburizing and Heat treatingVacuum Carburizing and Heat treating Composition & processing affect material properties

9. Section 6.1-6.3 Mechanical Properties of Metals: Elastic Deformation: Stress-Strain behavior

10. Mechanical Properties: How will the object respond to an applied load (force)? Stiffness Ductility Strength Toughness Hardness

11. Tension Compression Shear

12. Tensile Test

15. Ductile Failure: Tensile Test of AlMgSi alloy

16. Brittle Failure: Tensile test of Nodular Graphite Cast Iron

17. Principles of Stress and Strain

18. What is it good for?

19. Normalize tensile tests Measure intensity of a load Stress is used to:

20. The Ultimate Chair Cushion Design

21. Types of Deformation Elastic Plastic

22. Elastic Deformation: Recoverable

23. Elastic By Design

24. Elastic deformation of Metals Motorcycle Shock absorber http://upload.wikimedia.org/wikipedia/commons/thumb/1/10/R75-rear-shock.jpg/220px-R75-rear-shock.jpg

25. Elastic deformation of Ceramics Fiber optic cable

26. Elastic deformation of Polymers Shooting a rubber band http://rickischultz.files.wordpress.com/2009/09/rubber-band.jpg

27. Elastic deformation of Composites Carbon-fiber prosthetic legs http://info.rogersathletic.com/get-strong/bid/62010/Muscle-Tendon-Springs

28. Elastic deformation of Composites Diving Board

29. Elastic deformation of Composites Diving Board

30. Quantifying Elastic Deformation

31. Hooke’s Law Elastic deformation–Recoverable:  = E  Stiffness – E – resistance to elastic deformation

33. Brittle Failure: Tensile test of Nodular Graphite Cast Iron

34. YouTube REAL Golf Ball hitting steel in slow motion by the USGA - YouTube

35. Comparison of E values

36. Plastic Deformation: Permanent

37. plastic (adj.) 1630s, "capable of shaping or molding" from L. plasticus, from Gk. plastikos "able to be molded, pertaining to molding,"

38. plastic (adj.) Main modern meaning, "synthetic product made from oil derivatives," first recorded 1909, coined by Leo Baekeland (see bakelite). Picked up in counterculture slang as an adj. meaning "false, superficial" (1963).

39. Mechanical Property: Elasticity–recoverable deformation Paper clip under normal use

40. Mechanical Property: Plasticity—permanent deformation Paper clip under abuse

41. Plasticity by design Radial profile segments

42. Plasticity by accident Street lamp damaged during storm (Bridgeport, CN)

43. Formed by plastic deformation; Behaves elastically Binder Clip

44. Plastic deformation of Metals–Spring shape Elastic deformation: Shock absorbers Springs absorb shock transmitted from road to vehicle.

45. Plastic Deformation Plastic deformation – Permanent Yielding – onset of plastic deformation Yield strength – Stress at yield (specified amount of strain).