Surface Technology Part 1 Introduction

1. Surface TechnologyPart 1Introduction Professor Kenneth W Miller Office A108 Phone 0841 9348 0324 Surface Technology

2. Topics for Today • Course Syllabus • Introductions • My background • What is your background • What are your areas of interest • Automobile Parts of Interest • Materials of Interest • What is Not Covered • Fundamentals of Materials Science Surface Technology

3. Automotive Parts of Interest • Body in White • Suspension Components • Brake Components • Steering Components • Space Frames • Accessories • Mirrors • Antenna Surface Technology

4. Enemies List • Metal to metal contact • Sun • Water • Salt • Rocks • Grocery carts • Time Surface Technology

5. Body and Frame Functions • Strength • Frame • A, B, and C Pillars • Suspension and Steering Components • Braking Components • Cosmetic • Body panels • hood Surface Technology

6. Steel Carbon Steel HSLA Stainless Steel New Alloys Aluminum Magnesium Polymers Composites Automotive Materials of Interest Surface Technology

7. What is Not Covered • Engine and engine components • Tires • Polymers will get limited coverage • underbody impact protection • body parts Surface Technology

8. Summary • Body in White is the Primary Topic • Steel is the Primary Material • Aluminum is Becoming Significant • Magnesium is of Limited Interest • What are the factors in material selection? Surface Technology

9. Material StructureAtomic Level • Patterns of Atoms • Unit Cells • Body-Centered Cubic (BCC) • Face-Centered Cubic (FCC) • Hexagonal Close Pack (HCP) Surface Technology

10. Material Structure - FCC Surface Technology

11. Material Structure -BCC Surface Technology

12. Material Structure - HCP Surface Technology

13. Energy and Packing • Non dense, random packing • Dense, regular packing Surface Technology 2

14. Material Structure - APF • Atomic Packing Factor • APF = Volume of atoms / Volume of cell • APF = 0.74 for FCC • APF = 0.68 for BCC • APF = 0.74 for HCP Surface Technology

15. Material StructureCoordination Number • Nearest neighbors and touching atoms • Coordination Number = 12 for FCC • Coordination Number = 8 for BCC • Coordination Number = 12 for HCP Surface Technology

16. Material Structure - FCC Surface Technology

17. Material Structure - BCC Surface Technology

18. Material Structure - HCP Surface Technology

19. Strength of Materials • Determined by bond strength • Limited by slip planes • Slip planes and dislocations • Split planes and inclusions • Atomic separation (distances) Surface Technology

20. Crystalline Defects Surface Technology

21. Bond Strength Surface Technology

22. Energy and Packing • Non dense, random packing • Dense, regular packing Surface Technology 2

23. Granular Structure • Pure metals are rarely used • Practical limits to crystalline structure • Can create anisotropy • Reflects heterogeneous composition • Caused and changed through • Forming operations such as casting • Working operations e.g. rolling, drawing • Heat treatment Surface Technology

24. Granular Structure Polycrystalline lead ingot Magnified 7x Surface Technology

25. Granular Structure • Size – effects strength • Size – effects toughness • Orientation – affects directional strength • Orientation at surface – corrosion opportunities • Can be seen through a small microscope • Crystalline structure requires special equipment Surface Technology

26. Strain • Engineering Strain • True Strain Surface Technology

27. Stress • Engineering Stress • True Stress Surface Technology

28. Stress and Strain • These are point functions • >0 for tension, <0 for compression • Both are directional • Both depend on plane considered • Normal stress and strain • Shear stress and strain • Full stress or strain state is represented as a 3x3 matrix Surface Technology

29. Stress and Strain Surface Technology

30. Material Properties • Tensile strength • Yield strength • Toughness • Hardness • Fracture toughness • Modulus of Elasticity • Poisson’s Ratio Surface Technology

31. Stress and Strain • Elastic Range – linear • σ = E · ε • E is the modulus of elasticity or Young’s Modulus • Full recovery, no permanent change • Plastic Range – non-linear • Varies with material • Work hardening • Necking • Permanent change to size and strength Surface Technology

32. Modulus of Elasticity Surface Technology

33. Modulus of Elasticity Surface Technology

34. Yield Point Surface Technology

35. Necking Surface Technology

36. Stress Strain • Power law relationship • Typical for steel and aluminum • Assumes slow strain • Assumes uniform temperature Surface Technology

37. Stress Strain Surface Technology

38. Poisson’s Ratio • Pull it and it gets thinner • Squish and it gets thicker • Consider a tensile specimen pulled in z • Upper limit is 0.5 for no material volume change Surface Technology

39. Material Properties Surface Technology

40. Discussion - Surfaces • Appearance • Cover minor flaws • Hide difference materials • Protection from Corrosion • Protection from scratches or impacts • Increase / decrease friction • Improve scratch resistance (hardness) Surface Technology

41. Manufacturing Considerations • Cost • Speed – timing for production • Downstream effects • Value to the consumer • Weight • Appearance • Safety Surface Technology

42. Manufacturing Cost • Materials • Time • Equipment • Flexibility (changeover time and cost) • Labor • Waste disposal (toxic?) Surface Technology