Engineering Materials Flashcards: Plastics, Metals and Processing

Cartes de ce paquet

1. Carte 1

   Question

   Engineering stress in a tensile test: force divided by what?

   Réponse

   Original specimen cross-sectional area.

2. Carte 2

   Question

   Engineering strain in a tensile test: extension divided by what?

   Réponse

   Original gauge length. Strain is dimensionless.

3. Carte 3

   Question

   Elastic deformation: what happens after unloading?

   Réponse

   The deformation recovers.

4. Carte 4

   Question

   Young’s modulus describes which material behaviour?

   Réponse

   Resistance to elastic tensile or compressive strain, in the linear elastic region.

5. Carte 5

   Question

   Yield strength marks the onset of what?

   Réponse

   Significant permanent deformation, using the specified yield or proof criterion.

6. Carte 6

   Question

   Ultimate tensile strength: which point on an engineering stress–strain curve?

   Réponse

   The maximum engineering tensile stress.

7. Carte 7

   Question

   Ductility describes what happens before tensile fracture?

   Réponse

   How much plastic deformation the material can undergo.

8. Carte 8

   Question

   Indentation hardness measures resistance to what?

   Réponse

   Localized permanent penetration by an indenter.

9. Carte 9

   Question

   Tensile toughness: what does the area under the stress–strain curve to fracture represent?

   Réponse

   Energy absorbed per unit volume up to fracture under those test conditions.

10. Carte 10

    Question

    Density relates which two quantities?

    Réponse

    Mass per unit volume.

11. Carte 11

    Question

    Thermal conductivity describes which ability?

    Réponse

    Transferring heat through a material under a temperature gradient.

12. Carte 12

    Question

    Electrical conductivity describes which ability?

    Réponse

    Carrying electric current under an electric field.

13. Carte 13

    Question

    Creep: what changes under a sustained load over time?

    Réponse

    Deformation increases with time; temperature and stress affect the rate.

14. Carte 14

    Question

    Fatigue damage is associated with what loading pattern?

    Réponse

    Repeated or fluctuating loading that can initiate and grow cracks.

15. Carte 15

    Question

    Brittle fracture: how much plastic deformation precedes it?

    Réponse

    Little plastic deformation compared with ductile fracture under the same test conditions.

16. Carte 16

    Question

    A bracket bends too far but recovers fully. Which property should you examine first?

    Réponse

    Elastic stiffness: material modulus together with the bracket’s geometry.

17. Carte 17

    Question

    A metal clip stays bent after one overload. Which threshold was exceeded locally?

    Réponse

    Its yield threshold; permanent deformation occurred.

18. Carte 18

    Question

    A housing must absorb a drop without fracture. Which evidence matters beyond tensile strength?

    Réponse

    Impact-test performance under relevant temperature, notch and geometry conditions.

19. Carte 19

    Question

    Two materials have equal yield strength. Must their tensile toughness be equal?

    Réponse

    No. Different ductility can produce different energy absorption before fracture.

20. Carte 20

    Question

    A plastic clamp slowly loosens at fixed deflection. Which time-dependent effect is this?

    Réponse

    Stress relaxation: the stress decreases while the imposed deformation is held.

21. Carte 21

    Question

    Does a higher hardness alone prove a part will resist every wear mechanism?

    Réponse

    No. Wear also depends on contact, loading, lubrication and the wear mechanism.

22. Carte 22

    Question

    Why compare impact results only with matching test conditions?

    Réponse

    Specimen geometry, notches, temperature and test method affect measured impact behaviour.

23. Carte 23

    Question

    Can a generic family property range serve as a finished-part design allowable?

    Réponse

    No. Select a grade, condition and relevant design data before qualifying the part.

24. Carte 24

    Question

    A lighter material is proposed for the same-size part. Which property predicts its mass change?

    Réponse

    Density, provided the volume remains the same.

25. Carte 25

    Question

    Ferrous versus nonferrous metals: what is the defining distinction?

    Réponse

    Whether iron is the main constituent. Nonferrous does not mean completely iron-free.

26. Carte 26

    Question

    Steel belongs to which basic alloy family?

    Réponse

    Iron-based alloys containing carbon, often with other alloying elements.

27. Carte 27

    Question

    Why specify a steel grade and heat treatment rather than just “steel”?

    Réponse

    Composition and processing change its microstructure and mechanical properties.

28. Carte 28

    Question

    What is a grain in a polycrystalline metal?

    Réponse

    A crystalline region with a particular lattice orientation.

29. Carte 29

    Question

    What separates neighbouring metal grains with different orientations?

    Réponse

    A grain boundary.

30. Carte 30

    Question

    Which crystal defect commonly moves during plastic deformation of metals?

    Réponse

    A dislocation.

31. Carte 31

    Question

    Cold working usually trades increased strength for what?

    Réponse

    Reduced ductility, as plastic deformation impedes further dislocation motion.

32. Carte 32

    Question

    What is a common purpose of annealing a cold-worked metal?

    Réponse

    Restore ductility and reduce hardness through a controlled heat treatment.

33. Carte 33

    Question

    Quenching in metal heat treatment means what cooling step?

    Réponse

    Rapid cooling using a specified medium; the appropriate regime depends on the alloy and intended result.

34. Carte 34

    Question

    What gives stainless steel much of its corrosion resistance?

    Réponse

    A thin chromium-rich passive surface film.

35. Carte 35

    Question

    Why distinguish grey cast iron from ductile cast iron during selection?

    Réponse

    Graphite form and resulting mechanical behaviour differ; “cast iron” is not one property set.

36. Carte 36

    Question

    Why are aluminium alloys often screened for lightweight structures?

    Réponse

    Their relatively low density can help reduce mass; stiffness, strength and geometry still need checking.

37. Carte 37

    Question

    Why is copper often screened for electrical conductors?

    Réponse

    High electrical conductivity; cost, strength and connection design also matter.

38. Carte 38

    Question

    Brass is principally an alloy of copper with which element?

    Réponse

    Zinc.

39. Carte 39

    Question

    Traditional tin bronze is principally an alloy of which two elements?

    Réponse

    Copper and tin. Other bronze families use different alloying additions.

40. Carte 40

    Question

    Does “stainless” mean immune to chloride corrosion?

    Réponse

    No. Grade, environment and surface condition still govern corrosion resistance.

41. Carte 41

    Question

    Two dissimilar metals touch in salty water. Which corrosion mechanism should be checked?

    Réponse

    Galvanic corrosion, because electrical contact and an electrolyte can form a galvanic couple.

42. Carte 42

    Question

    Can you rank aluminium and steel parts by stiffness using only their material names?

    Réponse

    No. Compare the actual moduli and part geometries for the required loading.

43. Carte 43

    Question

    A copper alloy is stronger than pure copper. Must it conduct electricity equally well?

    Réponse

    No. Alloying changes conductivity as well as mechanical properties; check that alloy’s data.

44. Carte 44

    Question

    A steel sheet cracks during forming after extensive cold work. What processing step may restore formability?

    Réponse

    An appropriate anneal before further forming; confirm the alloy-specific procedure.

45. Carte 45

    Question

    What is a common purpose of tempering a quench-hardened steel?

    Réponse

    Improve toughness and ductility, usually with some reduction in hardness.

46. Carte 46

    Question

    How can an insulating washer help a dissimilar-metal joint resist galvanic corrosion?

    Réponse

    By interrupting the electrical connection, if the whole joint is electrically isolated.

47. Carte 47

    Question

    Before approving a welded metal component, which material region besides the weld metal needs consideration?

    Réponse

    The heat-affected zone, whose thermal cycle can change properties without melting it.

48. Carte 48

    Question

    What is the key processing–structure–property lesson for metal selection?

    Réponse

    A chemical composition alone does not determine performance; processing changes microstructure.

49. Carte 49

    Question

    A polymer is built from what kind of molecular structure?

    Réponse

    Large molecules containing many linked repeating units.

50. Carte 50

    Question

    Which polymer class can usually be reheated and reshaped: thermoplastics or cured thermosets?

    Réponse

    Thermoplastics. Cross-links in a cured thermoset prevent ordinary melt reshaping.

51. Carte 51

    Question

    What deformation behaviour distinguishes an elastomer?

    Réponse

    It can undergo substantial deformation and recover toward its original shape when the load is removed, within its working range.

52. Carte 52

    Question

    What does “semi-crystalline polymer” mean?

    Réponse

    Ordered crystalline regions coexist with amorphous regions.

53. Carte 53

    Question

    Which polymer regions undergo glass transition: amorphous or crystalline?

    Réponse

    Amorphous regions. Around the glass transition, motion of chain segments becomes much easier.

54. Carte 54

    Question

    What structural feature prevents a cured thermoset from flowing like a thermoplastic melt?

    Réponse

    A covalently cross-linked network.

55. Carte 55

    Question

    Why are plasticizers added to some polymer formulations?

    Réponse

    To increase flexibility; the amount and compatibility affect the final properties.

56. Carte 56

    Question

    Why add UV stabilizers to a polymer intended for outdoor exposure?

    Réponse

    To reduce degradation caused by ultraviolet exposure; the formulation and exposure still need verification.

57. Carte 57

    Question

    Why can adding glass fibres make moulded polymer properties direction-dependent?

    Réponse

    Fibres become oriented during flow, so reinforcement differs with direction.

58. Carte 58

    Question

    What structural change separates glass transition from crystalline melting in a polymer?

    Réponse

    Glass transition increases chain-segment mobility in amorphous regions; melting breaks down the ordered crystalline regions.

59. Carte 59

    Question

    ABS is an abbreviation for which polymer name?

    Réponse

    Acrylonitrile butadiene styrene.

60. Carte 60

    Question

    PA6 is another name for which polyamide?

    Réponse

    Polyamide 6, also called nylon 6.

61. Carte 61

    Question

    Why distinguish “dry” from “conditioned” polyamide property data?

    Réponse

    Moisture conditioning changes the material state and can change mechanical behaviour.

62. Carte 62

    Question

    Does one grade’s ABS datasheet establish the properties of every ABS grade?

    Réponse

    No. Formulation, grade, test method and conditions must match the claim.

63. Carte 63

    Question

    INEOS Terluran GP-22 is specified for which main shaping process?

    Réponse

    Injection moulding; it is a general-purpose ABS grade.

64. Carte 64

    Question

    BASF Ultramid B3S is supplied for which main shaping process?

    Réponse

    Injection moulding; BASF describes this PA6 grade as easy-flowing and finely crystalline.

65. Carte 65

    Question

    A warm polymer bracket carries a constant load for months. Which data are needed beyond a short tensile test?

    Réponse

    Long-term creep data for the relevant load, temperature and material condition.

66. Carte 66

    Question

    Ultramid B3EG6 differs from unreinforced PA6 by which reinforcement?

    Réponse

    BASF specifies glass-fibre reinforcement for this PA6 injection-moulding grade.

67. Carte 67

    Question

    Which part category does INEOS identify as a particular application for Terluran GP-22?

    Réponse

    Housings, including appliance housings. This is a candidate application, not automatic design approval.

68. Carte 68

    Question

    Why keep opened Ultramid B3S granule containers carefully closed?

    Réponse

    To limit moisture absorption before processing.

69. Carte 69

    Question

    Can glass-filled PA6 data replace unfilled PA6 data in a design check?

    Réponse

    No. Reinforcement changes the material; use the exact grade and relevant orientation data.

70. Carte 70

    Question

    Must a thermoplastic part be accepted by the local recycling system?

    Réponse

    No. Remeltability alone does not establish collection, sorting or recycling compatibility.

71. Carte 71

    Question

    For an outdoor ABS housing, is a good indoor impact result enough evidence?

    Réponse

    No. Check weathering, temperature and the exact grade’s suitability for the exposure.

72. Carte 72

    Question

    BASF lists grips and fixing clamps for Ultramid B3S. What remains to verify for a loaded clamp?

    Réponse

    Grade-specific long-term behaviour at the actual temperature and moisture state, plus the part geometry.

73. Carte 73

    Question

    Metal casting shapes a part by which change of state?

    Réponse

    Liquid metal solidifies inside a mould.

74. Carte 74

    Question

    Forging shapes metal by what basic mechanism?

    Réponse

    Compressive plastic deformation of solid metal; it may be performed hot or cold.

75. Carte 75

    Question

    Extrusion is particularly suited to which basic geometry?

    Réponse

    A continuous length with a substantially constant cross-section, formed through a die.

76. Carte 76

    Question

    CNC machining is additive or subtractive?

    Réponse

    Subtractive: controlled cutting removes material from a workpiece.

77. Carte 77

    Question

    Injection moulding of a thermoplastic: what happens after the cavity fills?

    Réponse

    The melt cools and solidifies before the part is ejected.

78. Carte 78

    Question

    Thermoforming starts from which form of plastic stock?

    Réponse

    A sheet heated until formable, then shaped over or into a mould.

79. Carte 79

    Question

    Blow moulding is commonly used for which type of plastic part?

    Réponse

    Hollow parts, such as bottles, formed by inflating a heated preform or tube in a mould.

80. Carte 80

    Question

    Additive manufacturing builds geometry by what basic approach?

    Réponse

    Adding material, commonly layer by layer, from a digital model.

81. Carte 81

    Question

    In milling, what typically rotates to remove material?

    Réponse

    The cutting tool.

82. Carte 82

    Question

    Why may a cast part still need machining?

    Réponse

    Selected surfaces may need tighter tolerances or a better finish than the casting provides.

83. Carte 83

    Question

    Sand casting and permanent-mould casting mainly differ in what tooling feature?

    Réponse

    Sand moulds are expendable; permanent moulds are reused.

84. Carte 84

    Question

    Why can injection moulding be costly for a very small production run?

    Réponse

    Tooling cost is spread across too few parts; compare total cost at the required volume.

85. Carte 85

    Question

    A long plastic tube has the same cross-section throughout. Which process is a natural first candidate?

    Réponse

    Extrusion, followed by cooling and cutting to length.

86. Carte 86

    Question

    A thin plastic packaging tray must be formed from sheet. Which process is a natural first candidate?

    Réponse

    Thermoforming; check wall thinning and the required detail.

87. Carte 87

    Question

    Why should a forged part’s grain flow be considered in design?

    Réponse

    Deformation creates directional structure; the load direction and process route affect performance.

88. Carte 88

    Question

    A design needs a few changing metal prototypes. Why consider CNC machining before buying a production mould?

    Réponse

    It can make revised parts directly from stock without dedicated mould tooling.

89. Carte 89

    Question

    What distinguishes a fusion-weld heat-affected zone from the fusion zone?

    Réponse

    The heat-affected zone changes thermally but does not melt; the fusion zone melts and resolidifies.

90. Carte 90

    Question

    Why clean and prepare a metal surface before applying a protective coating?

    Réponse

    Contaminants and surface defects can impair coating adhesion and performance.

91. Carte 91

    Question

    Does a corrosion-resistant coating make the underlying material irrelevant?

    Réponse

    No. Damage, adhesion, exposure and substrate compatibility still matter.

92. Carte 92

    Question

    Why check build orientation when selecting a layer-built polymer part?

    Réponse

    Layer bonding and deposition can make strength depend on direction.

93. Carte 93

    Question

    A hollow plastic bottle needs a shaped enclosed body. Which process family should you screen first?

    Réponse

    Blow moulding; select the exact variant for the material and geometry.

94. Carte 94

    Question

    Many identical thermoplastic housings are needed. Which process deserves early cost comparison?

    Réponse

    Injection moulding, because repeat production can spread tooling cost over many parts.

95. Carte 95

    Question

    Why does choosing a process also affect material selection?

    Réponse

    Materials must tolerate that process and achieve the required finished-part properties.

96. Carte 96

    Question

    Before releasing a selected material–process combination, what evidence closes the selection loop?

    Réponse

    Verify the exact grade, processing condition and part performance against the actual requirements.

96 cartes

Engineering Materials Flashcards: Plastics, Metals and Processing

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