Materials

1 SEMESTER Materials course at WUT, Mechatronics department

75 flashcards · Other · by Aida Muravyeva

1. 1) Polymers: a) Typical thermosets are Polyethylene, Polypropylene and Polystyrene b) Typical thermosets are Epoxies and Polyurethanes c) Typical thermoplastics are Epoxies and Polyurethanes d) Typical thermoplastics are Polyethylene, Polypropylene and Polystyrene

   b) Typical thermosets are Epoxies and Polyurethanes d) Typical thermoplastics are Polyethylene, Polypropylene and Polystyrene

2. Medium-carbon steels: a)cContain 0.25-0.6% C b) Can be quench, hardened and tempered (better quality grades) c) Are commonly used for tools and springs d) Contain 0.6-1.0% C

   Contain 0.25-0.6% C Can be quench, hardened and tempered (better quality grades

3. Rolling bearings are often produced from:

   d) Steels containing around 1% C and 1,5% Cr

4. Ceramics are characterized by high: a) Brittleness b) Thermal shock resistance c) Hardness d) Resistance to mechanical vibration

   Hardness Brittleness

5. Vulcanization process: a) Crystallize the polymer b) Crosslinks the macromolecules c) Decrease the strength of polymers d) Increase the strength of polymers

   Crosslinks the macromolecules Increase the strength of polymers

6. Degree of the polymerization (DP): a) Is determined by number of monomer units in a macromolecule b) The strength of polymers decreases with increasing DP c) The strength of polymers increases with increasing DP d) Is determined by time needed to finish the polymerization process

   Is determined by number of monomer units in a macromolecule The strength of polymers increases with increasing DP

7. Commercial glasses: a) Are based on zirconium oxide (zirconia). b) Are based on aluminum oxide (alumina). c) Have positive ions added to the structure to reduce the glass temperature. d) A based on silicon oxide (silica).

   Have positive ions added to the structure to reduce the glass temperature. A based on silicon oxide (silica).

8. Thermoset polymers: a) During heating decompose before melting b) Consist of cross-linked macromolecules c) Almost always have crystalline structure

   During heating decompose before melting Consist of cross-linked macromolecules

9. 9) Which has the highest specific strength (yield stress divided by density): a) β-Titanium alloys b) β-aluminum alloys c) HSLA steels d) α-aluminum alloys

   β-Titanium alloys

10. 10) Aluminum alloys: a) For high strength shall contain 0.5-1.5%C b) Are often quench hardened and tempered c) Are often solution heat treated and aged d) Have high corrosion resistance due to tight oxides layer

    Are often solution heat treated and aged Have high corrosion resistance due to tight oxides layer

11. In dry environments, oxidation process of metals can be controlled by:

    Diffusion of ions through the oxide film.

12. 12)Wet corrosion in presence of cracks on metal surface: a) Region inside crack becomes reach in oxygen, so the corrosion is faster. b) Corrosion occurs at crack tip, leading to crack growth. c) Electrons migrate from crack (anodic region) to free surface (cathodic region). Oxides from inside the crack until it is completely filled.

    Corrosion occurs at crack tip, leading to crack growth Electrons migrate from crack (anodic region) to free surface (cathodic region).

13. 13)Which of the alloying elements is least effective in forming protective layers by preferential oxidation on steel: a) Mn. b) Si. c) Al. d) Cr.

    a) Mn.

14. 14)Which of the quoted below alloys doesn’t show ductile-to-brittle transition at low temperature? a) Carbon steel. b) Austenitic steel. c) All alloys show this effect. d) Copper alloys.

    Austenitic steel Copper alloys.

15. 15)During wet corrosion: a) The higher potential is needed to stop the oxidation reaction the is tendency for oxidation. b) The rate of loss of a material increases, because hydrated oxides are formed. c) The diffusion rate in a material body increases d) The lower potential is needed to stop the oxidation reaction the higher is tendency for oxidation.

    b) The rate of loss of a material increases, because hydrated oxides are formed.

16. 16)Tensile strength (TS) is defined as the ratio of: a) The force at which material starts to deform plastically to the sample cross section area after the test. b) The force at rupture to the area of the sample cross section area before the test. c) The maximum force to the sample cross section area before the test. d) The force at rupture to the area of the sample cross section area after the test

    The maximum force to the sample cross section area before the test.

17. 17)Which alloy microstructure would have the highest resistance to creep: a) Columnar structure b) Polycrystalline fine structure c) Single-crystal structure d)Polycrystalline coarse structure

    Single-crystal structure

18. 18)When plastic deformation occurs at under constant load over a long time period: a) Creep rate increases exponentially with temperature. b) Dependence of creep rate on temperature is parabolic. c) For most polymers creep is a problem already at room temperature. d) Creep rate is higher for higher applied loads

    Creep rate is higher for higher applied loads NOTES:a) Creep rate increases exponentially with temperature. This is a common and often accurate empirical observation for many materials, but it is not a universal rule for all materials or for all conditions. The relationship is often complex and can be better described by various empirical models.

19. 19)When designing parts where friction is important one shall remember that: a) When ceramics slide on ceramics friction coefficient is high b) A little oxygen or water greatly reduces coefficient of friction. c) When hard metals slide the junctions are small so friction coefficient is low. d) When surfaces are cleaned in vacuum friction coefficient is high

    When ceramics slide on ceramics friction coefficient is high When surfaces are cleaned in vacuum friction coefficient is high NOTES: When ceramics slide on ceramics friction coefficient is high: This is generally true, as ceramic-on-ceramic friction coefficients can be high (0.5 to 1.0) due to their hardness and the lack of a natural lubricant.

20. 20)Yield strength (YS) is defined as the ratio of the force at: a) The force at rupture to the area of the sample cross section area before the test. b) The maximum force to the sample cross section area after the test. c) The force at which material starts to deform plastically to the sample cross section area after the test. d) which material starts to deform plastically to the sample cross section area before the test.

    which material starts to deform plastically to the sample cross section area before the test.

21. 21) Which processes could be used to decrease tensile strength of normalized carbon steel a) Normalizing b) Quench hardening and tempering c) Stress relief annealing d) Full annealing

    Stress relief annealing Full annealing

22. 22) Charpy test (impact loading) could be used to: a) Measure fracture toughness (critical strain energy release rate) b) Find a temperature of ductile-to-brittle transition c) Study material behavior at high deformation rate d) Measure hardness and percentage elongation of material

    Find a temperature of ductile-to-brittle transition Study material behavior at high deformation rate

23. 23)Brittle material (as for instance most of ceramics) a) There is visible/measurable necking during tensile test. b) Stress-strain curve is linear c) Fracture during compression test happens at higher loads than during tensile test d) Elastic recovery is observed for specimen loaded above yield strength but below ultimate tensile strength.

    Stress-strain curve is linear Fracture during compression test happens at higher loads than during

24. 25) The effect of tempering of the quench hardened material its properties change as follow: a) The fracture toughness of the quenched material increase b) The strength of the quenched material increase c) The elongation of the quenched material increase d) The elongation of the quenched material decrease

    The effect of tempering of the quench hardened material its properties change as follow: The fracture toughness of the quenched material increase The elongation of the quenched material increase

25. 26)Hot-working of the alloy is: a) Impossible b) Harder than cold working c) Easier than cold working d) As easy as cold working

    Easier than cold working

26. 24)How to produce nanostructured materials? a) By carburizing of low-carbon steel. b) By hydrostatic extrusion. c) By severe plastic deformation by Equal-Channel Angular Pressing. d) By austempering (heating steel in austenite arnge and quenching in a molten salt)

    By severe plastic deformation by Equal-Channel Angular Pressing.

27. 27)Which of these types of atomic bounds are primary bounds: a) Van der Waals bonds b) Metallic bounds c) Hydrogen bounds d) Covalent bounds

    Metallic bounds Covalent bounds

28. 28)Eutectoid reaction in given binary phase diagram: a) Is liquid-solid reaction b) Has lower temperature than eutectic reaction c) Occurs at constant temperature d) Has higher temperature than eutectic reaction

    Has lower temperature than eutectic reaction Occurs at constant temperature

29. 29)The diffusion coefficient of atoms increases exponentially with the temperature because: a) The density of vacancies increases b) The amplitude of atom’s vibration increase c) The density of vacancies decreases d) The frequency of atom’s vibration increase

    The density of vacancies increases The amplitude of atom’s vibration increase

30. 30)Which structure will have lowest atomic packing factor (APF): a) Amorphous b) Crystalline body centered cubic (B.C.C.) c) Crystalline hexagonal close-packed (H.C.P.) d) Crystalline face centered cubic (F.C.C.)

    Crystalline body centered cubic (B.C.C.)

31. 31)The Gibbs rule (at atm. Pressure F = C – P + 1) allows degrees of freedom calculation for known: a) Components, phases and structural elements numbers b) Components number and temperature value c) Structural elements and phases numbers d) Phases and components numbers

    Phases and components numbers

32. 32)The diffusion: a) Decrease with increasing temperature b) Do not depend on temperature c) Occurs only in solid phase d) Increase with increasing temperature

    Increase with increasing temperature

33. 33)Hook’s Law is valid for: a) Tensile strains only b) Any strains c) High strains d) Low strains

    Low strains

34. 34)Structural constituent is: a) A metal or ceramics composed of more than one chemical element b) Separated from the remainder material by a boundary surface called an interface c) A chemically and structurally homogeneous portion of the material microstructure d) A characteristic, metallographically discernible component of the microstructure.

    A characteristic, metallographically discernible component of the microstructure.

35. 35)Plastic deformation of metals and their alloys at room temperature: a) Increase their strength b) Metals and their alloys cannot be deformed plastically at room temperature c) Does not change their strength d) Decrease their strength

    Increase their strength

36. 36)Diffusion is fast for: a) Close-packed structures b) Small diffusing atoms c) Materials w/covalent bonding d) Low density materials

    Low density materials Small diffusing atoms

37. 37)The most frequently used metals have: a) mono-crystalline structure b) polycrystalline structure c) amorphous structure d) heavy cross-linked structure

    polycrystalline structure

38. 38)Composites are: a) two or more phase metals b) inorganic glasses c) combination of the two or more different type of materials d) covalent cross-linked polymers

    combination of the two or more different type of materials

39. 39)Titanium alloys show: a) high specific strength b) low specific strength c) high stiffness d) low stiffness e) high resistance to corrosion f) f) low resistance to corrosion

    high specific strength low stiffness high resistance to corrosion

40. 40)Fast fracture of material occurs when: a) stress reaches the yield strength of the material b) at a given stress the crack length reaches critical value c) for a given crack length stress reaches critical value d) the strain reaches the percentage elongation to fracture of the material

    at a given stress the crack length reaches critical value for a given crack length stress reaches critical value

41. 41)What kind of hardening method can be used for alloys which show solid solubility limit increasing with the temperature (e.g. aluminium alloys)? a) cold working b) quench hardening and tempering c) precipitation hardening d) inoculation process

    precipitation hardening cold working

42. 42)Ceramics show: a) low stiffness b) high stiffness c) low fracture toughness d) high fracture toughness e) low density f) high density

    low fracture toughness high stiffness low density

43. 43)The strength of polycrystalline materials at room temperature can be increased by: a) decreasing of the grain size b) increasing of the grain size c) making easier of the dislocation movement d) making harder of the dislocation movement

    increasing of the grain size making harder of the dislocation movement

44. 44)Cold working of metals and their alloys cause: a) decrease of their strength b) increase of their strength c) does not change their strength d) increase dislocation density e) decrease dislocation density

    increase of their strength increase dislocation density

45. 45)Tensile strength of the carbon steels: a) increase with increasing of the carbon content b) decrease with increasing of the carbon content c) increase with the carbon content till 0.8% carbon then decrease d) does not change with the carbon content e) increase with the refining of ferrite and cementite f) decrease with the refining of ferrite and cementite g) refining of the ferrite and cementite in the microstructure has no influence

    Increase with increasing of the carbon content increase with the carbon content till 0.8% carbon then decrease decrease with the refining of ferrite and cementite

46. 54)Dislocations a) are 1-D defects b) are 2-D defects c) are characterised by Hook's vector d) can have twin orientation

    are 1-D defects

47. 52)Which structure doesn’t show ductile to brittle transition at lower temperature: a) h.c.p. structure metals are used. b) b.c.c. structure metals are used. c) f.c.c. structure metals are used.

    f.c.c. structure metals are used.

48. 51)Arrange structures from the highest to the lowest strength: a) 2 lower bainite. b) 3 upper brainite. c) 5 course pearlite. d) 4 fine pearlite. e) 1 martensite.

    martensite, lower bainite, upper bainite, fine pearlite, course pearlite.

49. 50)Which of the quoted below cyclic loaded materials show the fatigue limit? a) steels. b) aluminum alloys. c) copper alloys. d) titanium alloys.

    steels.

50. 49)Fast fracture of material occurs when: a) stress reaches the yield strength. b) at a given stress the crack length reaches critical value c) for a given crack length stress reaches critical value. d) the strain reaches the percentage elongation to fracture.

    at a given stress the crack length reaches critical value for a given crack length stress reaches critical value.

51. 48)Tempering process of the quench hardened steels is used for a) increasing strength and ductility. b) decreasing strength and ductility. c) increasing strength and decreasing ductility. d) decreasing strength and increasing ductility.

    decreasing strength and increasing ductility.

52. 47)Which alloys can be quench hardened? a) one-phase alloys b) in which the solid solubility limit increases with increasing temperature. c) alloys with allotropy (which have different crystalline structure at different temperatures). d) all types of alloys. underline the alloys which can be precipitation hardened.

    alloys with allotropy (which have different crystalline structure at different in which the solid solubility limit increases with increasing temperature. b and c, b is underlined

53. 46)Which cast iron has the best mechanical properties? a) grey (ordinary) cast iron. b) white cast iron. c) spheroidal cast iron. underline the cast iron showing good dumping capacity.

    grey (ordinary) cast iron.

54. 45)Tensile strength of the carbon steel: a) increase with increasing of the carbon content. b) decreases with increasing of the carbon content. c) increases with carbon content till 0.8% carbon then decreases. d) does not change with carbon content.

    increases with carbon content till 0.8% carbon then decreases.

55. 45)Tensile strength of the carbon steels: a) increase with increasing of the carbon content b) decrease with increasing of the carbon content c) increase with the carbon content till 0.8% carbon then decrease d) does not change with the carbon content e) increase with the refining of ferrite and cementite f) decrease with the refining of ferrite and cementite g) refining of the ferrite and cementite in the microstructure has no influence

    increase with the carbon content till 0.8% carbon then decrease decrease with the refining of ferrite and cementite

56. 46)The definition of the fatigue process is: a) plastic deformation of the material under increased loading at RT b) crack forming and growth under cycled stress at RT c) plastic deformation of the material under constant loading at high temperature d) plastic deformation of the material under increased loading at high temperature

    crack forming and growth under cycled stress at RT

57. 48)Recrystallization is the process at which: a) new, undeformed grains nucleate and grow in the heated cold-worked materials b) intensive grain growth in the heated cold-worked materials is observed c) dislocation rearrange to into low angle grain boundaries in the heated coldworked material d) dislocation density in the heated cold-worked materials drops to its original value

    A new, undeformed grains nucleate and grow in the heated cold-worked materials dislocation density in the heated cold-worked materials drops to its original value

58. 49)High ductility of the pure metals is the effect of their: a) weak metallic bonds b) amorphous structure c) low resistance to dislocations movement d) lack of dislocation

    low resistance to dislocations movement

59. 50)Factors increasing fatigue life: a) mean stress increasing b) mean stress decreasing c) surface polishing d) surface roughening e) surface hardening (carburizing, nitriding) f) hardening the whole material

    mean stress decreasing surface polishing surface hardening (carburizing, nitriding)

60. 51)Martempering enable: a) to obtain better hardness than common quench hardening and tempering b) reduce thermal stresses during quench hardening c) simplify the heat treatment process d) reduce the cost of the heat treatment process

    simplify the heat treatment process reduce the cost of the heat treatment process

61. 53)Spheroidal cast iron is produced by: a) heat treatment of the white iron b) addition of Mg-Ni alloy or Mg-Cu alloy powders directly before casting c) addition of Si-Fe alloy powder directly before casting d) increasing the cooling rate of the castings

    ddition of Mg-Ni alloy or Mg-Cu alloy powders directly before casting

62. 60) Arrange the following structures according to increasing their atomic packing factor (APF): a) crystalline body-centered cubic (b.c.c.) b) crystalline face-centered cubic (f.c.c.) c) crystalline hexagonal close-packed (h.c.p.) d) amorphous

    amorphous 1 crystalline body-centered cubic (b.c.c.) 2 crystalline face-centered cubic (f.c.c.) 3 c) crystalline hexagonal close-packed (h.c.p.) 3

63. 61) Brittlement of the ceramic materials is the effect of their: a) strong atomic bounds b) amporphous structure c) lack od dislocations d) high resistance to dislocations movements

    strong atomic bounds

64. 63) Which diffusion of atoms is quicker: a) volume diffusion b) gross boundary diffusion The diffusion: c) increase with increasing temperature d) decrease with increasing temperature

    gross boundary diffusion increase with increasing temperature

65. 65) Plastic deformation of crystalline materials is easier when: a) they haven’t any dislocations b) they contain a few dislocations c) they contain very many dislocations

    they contain a few dislocations

66. 66) Overcooling (the difference between melting point and the cooling temperaturę) during crystallization of th(...) forming of: a) the coarse (big grain size) microstructure b) the fine (small grain structure) microstructure c) has no influence on the microstructure

    the coarse (big grain size) microstructure

67. 67) Mention the types of atomic bonds. Underline primary bonds: a) metallic b) covalent c) ionic d) Van der Waal e) hydrogen

    a) metallic b) covalent c) ionic underline all 3

68. 68) Definition of fatigue proces: a) plastic deformation of the material under increased... loading at b) crack forming and growth under cycled stress c) plastic deformation of the material under increased loading at high temperature d) plastic deformation of the material under increased loading at high temperaturę

    crack forming and growth under cycled stress

69. 71) The best plain bearings are made as: a) thin Al-Sn surface layer on slightly softer and thicker Pb-Sn second.... b) thin Pb – Sn surface layer on slightly harder and thicker Al-An second... c) Thick Cu-Sn-P or Sn-Cb-Cu alloys d) white cast iron

    thin Pb – Sn surface layer on slightly harder and thicker Al-An second...

70. 72) What kind of cast iron has the best vibrational damping capacity? a) grey (ordinary) cast iron b) white cast iron c) spheroidal cast iron d) malleable cast iron

    grey (ordinary) cast iron

71. 73) Arrange the following composites according to decreasing stiffness: (cpntinuous fiber stiffness = 2*chopped fiber stiffness (or 5* chopped fiber below crit.lenght) a) Continuous glass fiber reinforced polymers when the fibers are paralel b) continuous glass fiber reinforced polymers when the fibers are woven c) chopped glass fiber reinforced polymers when the fibres are paralel d) chopped glass fiber reinforced polymers when the fibres are woven

    a, b,d,c

72. 74) Arrange according to decreasing resisatnce to corrosion a) ocide ceramic b) carbon steel c) chromium containing alloy steel d) magnesium alloy

    chromium containing alloy steel ocide ceramic carbon steel magnesium alloy

73. 75) Which polymers can be crystallized? a) elastomers b) thermosets c) thermoplastics d) no on polimer can be crystallized

    elastomers thermoplastics

74. Structural constituent is: a) A metal or ceramics composed of more than one chemical element b) Separatedfromtheremaindermaterialbyaboundarysurfacecalledan interface c) A chemically and structurally homogeneous portion of the material microstructure d) Acharacteristic,metallographicallydiscerniblecomponentofthe microstructure.

    d) Acharacteristic,metallographicallydiscerniblecomponentofthe microstructure.

75. Indryenvironments,oxidationprocessofmetalscanbecontrolledby: a) Diffusion of oxygen in the metal body b) Diffusion of metal and oxygen atoms through the oxide film c) Conduction of electrons through the oxide film d) Diffusion of ions through the oxide film.

    c) Conduction of electrons through the oxide film d) Diffusion of ions through the oxide film.