Met 121 Final

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Met 121 Final
2011-05-06 12:09:33
Met Final

Met 121 Final
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  1. The Met 121 course will focus on which step in the "Manufacturing Sequence"?
    Material Selection
  2. The first few weeks of the course hace focused primarily on this aspect of materials.
  3. Materials in this family often exhibit good strength and good ductility. They are also good electrical and thermal conductors.
  4. Materials in this family are typically light weight, but are generally not suitable for elecated temperature applications. They can be used to probide electrical insulation.
  5. In this type of bonding, the bonds are "directional" (wanting a set and limited number of nearest neighbors). The resulting materials have relatively low density.
  6. In this type of bonding, electrons transfer from donor atoms to receiving atoms, creating charged atoms, which then are electrostatically attracted to one another. Electrical conductivity, therefore, requires the movement of atoms and not electrons.
  7. All of the bonding electrons are tied up within molecules in this tupe of bonding. If the charge is not distributed uniformly within the molecules, a weak electrostatic attraction can occur between the polarized molecules.
  8. In a crystalline lattice, the number of adjacent or nearest neighbors is called the:
    Coordination number
  9. Metallic-bonded materials prefer crystal structures with ____ packing and a ___ coordination number.
    Dense, High
  10. In the body-centered cubic (BCC) crystal structure, atoms touch along the:
    Body diagonals
  11. The coordination number for a structure that contains close-packed planes is:
  12. The cubic crystal structure that contains close-packed planes stacked in the ABCBC sequence is:
  13. Compared to materials with other structures, materials with the FCC structure tend to:
    Have greater ductility
  14. The packing factor for structures involving stacked close-packed planes is:
  15. The directions of atom-touching in Fcc crystals have the Miller Indices form of:
  16. The Miller indices for direction A are:
  17. The Miller indices for direction B are:
  18. The Miller indices for plane C are:
  19. The Miller indices for plane D are:
  20. Properties that assume different values when measure in different direction are said to be:
  21. Adding imperfections to a commercial metal (already contains defects) will almost always ___ the strength and ___ the ductility.
    Increase, Decrease
  22. A material has 16 grains per square inch when biewed at 100x magnigication. According to ASTM, it would have an ASTM grain size number of:
  23. The type of point defect that assumes a significant role in atomic diffusion is the:
  24. The type of crystalline defect whose movement procides the plastic deformation observed in ductile metals is the:
  25. This type of defect is responsible for the strength of metal being considerably less than the calculated theoretical strength of several million pounds per square inch.
  26. Because this structure has four non-parallel slip planes {111} with three slip directions in each for a total of 12 slip systems, it exhibits exceptional ductility.
  27. The total absence of close-packed planes in this structure makes slip extremely difficult (highest critical resolved shear stress), and results in materials with high strength.
  28. According to Schmid's Law (t=o cos y cos a), the applied load is most effective in inducing shear when:
    • a=90 degrees
    • cos 90 = 0
  29. The two most common mechanisms for atom movement (diffusion) are:
    Vacancy and Interstitial
  30. In Fick's First Law, J = -D dc/dx, the resultant movement of atoms is represented by this term:
  31. As the temperature is invrease in the range of atomiv diffusion, we would expect the rate of atom movement to ___ with temperature.
    Increase exponentially
  32. We can estimate the temperature where diffusion becomes significat as:
    0.4 times the melting point in absolute temp.
  33. The activation energy (the Q in the Do= D e -Q/RT) is a measure of the:
    Energy required to cause anatom to move position within a crystal
  34. Since it would be the most tightly-bonded, the highest temperature would be required to activate movement of an atom lying:
    Within a crystal
  35. Becuase of the type of bond, diffusion would be easiest to activate in materials with ___ bonding.
  36. Which of the following is NOT a standard condition for at ensile test?
    Rapid rate of loading
  37. In a standard tensile test, the elastic response is associated with:
    The stretching of atomic bonds
  38. The stiffness or rigidity of amaterial can be evaluated by this property:
    Modulus of Elasticity
  39. Engineering stress is defined as:
    Applied load/original area
  40. When the elastic-to-plastic transition is not distinct, we often define and agree on:
    An offset yield strength
  41. In the plastic region of the tensile test:
    The material is always getting stronger
  42. The "ductility" of a material can be measured by which two tensile test properties?
    Elongation and reduction in area
  43. "Toughness" is a measure of a material's:
    Resistance to fracture
  44. If we want a steel to not be brittle, it should be used at a temperature ___ its Ductile-to-Brittle Transition (DBTT)
  45. This most coommon form of mechanical failure creates "striations: on the fracture surface.
  46. This tupe of test is the quickest and least expensive to conduct, and is frequently used as a quality control check during manufacturing operation.
  47. An S-N (stress vs. number of cycles) diagram is a collection of data from this tupe of test.
  48. Rockwell and Brinell are the two most common types of ___ test.
  49. Compared to my other courses, I find Met. 121 to be:
    • A. a piece of cake!
    • B. A real #@*$
    • B. More interesting
    • D. A real snoozer
  50. Which of the following properties does NOT increase during cold working?
  51. The change in properties that is obserced as we cold work a material is attributed to:
    A significant increase in disocations and increased grain boundary surface
  52. Which of the following is NOT a correct statement wabout cold working?
    A. We can strengthen the material while producing a desired shape.
    B. Anisotropy and residual stresses are always detrimental and should be removed prior to use
    C. Dimensional tolerances and surface finish tend to be good
    D. The process is often limited by fracture
    Anisotropy and residual stresses are always detrimental and should be removed prior to use
  53. Cold working is very effective means of strengthening materials with this crystal structure:
  54. During this stage of annealing, strength continues to drop, but there is no companion improvement in other properties. This stage is usually considered to be undesirable.
    Grain growth
  55. During this stage of annealing, new grains nucleate and grow, ductility is restored, and strength drops significantly.
  56. This is the metallurgical "process: that is responsible for the structure and property changes that occcur during annealing.
  57. Which of the following is NOT a possible reason for annealing a cold-worked metal?
    A. Relieve residual stresses
    B. Enhance conductivity
    C. Increase or restore ductility
    These are all possible reasons
  58. If we weld cold worked metal, we would expect the metal that is immediately adjacent to the weld to:
    Undergo recovery, recrystalliztion and grain frowth and be a weak location
  59. During hot working:
    Recrystallization continually removes the effects of deformation.
  60. Heterogeneous nucleation is most likely to:
    Begin on a mold wall
  61. If the size of a nucleating solid is less than the critical radius for a griven temperature, ___:
    It will remelt- i.e. return to liquid
  62. Inoculation is a special means of inducing:
    Heterogeneous nucleation
  63. Dendritic growth occurs when the liquid lying just ahead of the solidification interface is:
    Below the melting point
  64. If a cooling curve contains a "thermal arrest", the material is:
    Going from liquid to solid at a fixed temperature
  65. Because of its unique grain structure, properties in this cast region are always anisotropic (vary with direction):
  66. Deoxidation and vacuum processing are two means of reducing or eliminating:
    Gas porosity
  67. Solid solution strengthening can be obtained through the addition of:
    Substitutional point defects or Interstitial point defects
  68. The atomiv radii of copper, zinc, aluminum, and tin are listed below. Based on this information, we would expect that the greatest increase in strength would be achieved through the addition of 2 percent of ___ to pure copper. ATOMIC RADII: Cu=1.278A; Zn=1.332A; Al=1.432A
    • Tin
    • Strength increases the most with the biggest difference in AR
  69. When we use solid solution strengthening to alter the properties of a metal, which of the following properties would be expected to DECREASE?
  70. Aluminum has a face-centered-cubic crystal structure. Magnesium is hexagonal-close-packed. As a result we would expect the solubility of magnesium in aluminum to be:
    Definitely limited
  71. If an alloy has a freezing range, complete solidification occurs when the temperature reaches the:
  72. The "tool" used to determine the composition (or chemistry) of the phases present in a two-phase mixture is the:
  73. For the 50% Bg alloy, the solidus temperature is approximately:
    350 C
  74. Upon cooling the 50% Bg alloy, the first solid to appear will be expected to have the composition of:
  75. If the 50% Bg alloy were cooled to 500 C under equilibrium conditions, we would expect to find ___% solid material.
    • 60%
    • (50-70)/(70-20)=30/50
  76. The chemistry of the solid present when the 50% Bt alloy is in eqyilibrium at 500 C is:
    70% Bg
  77. The eutectic composition is ___ and the temperature of the eutectic reaction is ___.
    40% An, 250 C
  78. The maximum solubility of Sn in Cg is:
    20% Sn
  79. The amount of primary beta phase that would appear in the 80% Sn alloy upon equilibrium cooling could be computed by which relation?
  80. For the 80% Sn alloy, the amount of eutectic structure present at room temperature can be best extimated by:
  81. The 80% Sn alloy would be considered to be:
  82. The composition of the last liquid to freeze during the equilibrium cooling of the 80% Sn alloy would be:
  83. The room temperature structure of the 80% Sn alloy would be best described as:
    Primary beta plus eutectic
  84. Which alloy listed below would be the best candidate for age hardening?
    15% Sn
  85. The sloped line separating the alpha and the alpha+beta region of the diagram is a ___ line.
  86. 400 C
  87. 600 C
  88. Alpha phase would be a:
    Solid solution of B in A
  89. Beta phase would be considered to be a:
    Nonstoichiometric intermetallic
  90. The generic form of a peritectoid reaction is:
    Solid 1+ Solid 2 >> Solid 3
  91. In the solution treat - quench - and age treatment sequence, the material is a supersaturated single phase solid solution:
    After quenching, but before aging
  92. To age a solution treated and quenched material, we should heat it:
    At a temperature below the solvus
  93. Which of the following statements is not true for age hardening?
    The reulting structure is non-equilibrium and will change if sufficiently heated
    A second-phase particle is a more effective strengthener than a coherent precipitate
    Age hardened materials will lose strength when they are fusion welded
    The precipitated phase can be brittle, since it is discontinuous
    A second-phase paarticle is a more effective strengthener than a coherent precipitate
  94. If elevated temperature is required to promote aging, the material is considered to be:
    Artificial aging
  95. If we increase the temperature of aging, we would expect the peak strength to ___, and the time required to achieve that strength to ___.
    Decrease, decrease
  96. The solution treatment step in age hardening is performed by heating the material to a temperature that is:
    Above the solvus
  97. Which of the following strengthening mechanisms would be preferred if we wish to retain useful strength at elevated temperature?
    Solid solution strengthening
  98. In a lamellar eutectic structure, much of the observed strength can be attributed to:
    Dispersion strengthening from the interphase boundaries
  99. That to Met. 121, I now know:
    • How to make my own freeze dried coffee
    • How to gain self esteem in a crowd of professional people (Latinize words)
    • How to make brittle metal from aluminum and copper
    • How to crash a closed fraternity party
    • All of the above!!!
  100. In the iron-carbon equilibrium phase diagram, the eutectoid transformation of ausstenite to pearlite occurs upon crossing the ___ line.
  101. The single phase known as ___ is really an intermetalic compound that forms between carbon and iron.
    • Cementite
    • Fe3C
  102. The room temperature BCC single phase that has a maximum solubility of only 0.02% carbon is known as:
  103. The elevated-temperature single-phase solid solution that can hold up to 2.11% dissolved carbon is known as:
  104. Most heat treatments begin with the formation of this structure, since it erases prior structures and its high solubility allows carbon and alloy elements to redissolve:
  105. This microstructure is a lamellar or layered mixture of alpha and FE3C.
  106. According to the equilibrium phase diagram cementite should always have a composition of:
  107. The primary phase that forms when cooling a hypoeutectoid steel between the A3 and A1 temperatures is:
  108. Which of the following is not an equilibrium single phase? i.e. one that appears in the iron-carbon equilibrium diagram?
  109. The amount of pearlite in an equilibrium-cooled 0.6 carbon steel would be about:
  110. The composition of the pearlite that forms in an equilibrium-cooled 0.6 carbon steel would be:
  111. The microstructure that forms below the nose but above the Ms temperature on a TTT (or IT) diagram is knkown as:
  112. Because the formation of martensite is a diffeusionless transformatin, the resulting martensite will always have a carbon content equal to:
    the austenite from which it formed
  113. Arrange the following microstructures of the TTT diagram in order of increasing strength:
    Pearlite, bainite, martensite
  114. Because martensite is a supersaturated solid solution of carbon in ron, the strength of martensite depends almost exclusively on:
    Its carbon content
  115. When martensite is heated to a temperature below the A1, the process is called:
  116. During tempering, martensite ___ strength and ___ ductility.
    Lose, Gains
  117. In the terms "coarse peralite" and "fine pearlite", the terms coarse and fine refer to:
    The interlamellar spacing
  118. If austenite has partially transformed to martensite and we wish to form more martensite, we should:
    Decrease the temperature
  119. An 8620 steel is a ___ steel with ___% carbon.
    Alloy, 0.20%C
  120. The heat treatment whose primary purpose is to enchance the machinability of high carbon steels by altering the form of the cementite is known as:
  121. Compared to normalizing of the same material, a full anneal will generally take ___ time and result in a final structure with ___ ductility.
    More, Greater
  122. Which of the following heat treatments is a final heat treatment designed to harden and strengthen the material?
    Full anneal
    Quench & Temper
  123. The slowest rate of cooling owuld be observed during:
    Full annealing
  124. An austempering treatment will result in the formation of a ___ microstructure:
  125. Retained austenite is most likely to form in a ___ steel?
    High carbon, Alloy
  126. The primary cause of quench cracking in steel is the fact that when the FCC austenite transforms to a low-temperature body-centered product, the material ___.
  127. Which of the following quench media would likely produce the fastest cooling?
  128. If a steel is cooled faster than the "critical cooling rate", we would expect the final microstructure to be:
  129. Compared to plain carbon steels, alloy steels have ___ hardenability, i.e. their critical cooling rates are ___.
    Higher, Slower
  130. 4340 and 8640 steels have the same carbon content. According to the Jominy curves provided:
    • The 4340 has higher hardenability than 8640
    • The 4340 line stays higher longer.
  131. A 9310 steel is austenitized and quenched to produce an as-quenched hardness of Rc40. If the process is not altered, but the steel is replaced by a 4320, we would expect the as-quenched hardness to be Rc___.
  132. Using the Jominy curves, we find that a good indicator of the carbon contect of a steel would be:
    The hardness at Jominy distance zero
  133. The highest strength steels would come from this category?
    Maraging steels
  134. The surface-modification treatments such as flame hardening, induction hardening and carburizing are usually employed to produce:
    A hard, wear resistant surface on a fracture-resistant base
  135. Flame hardened or induction hardened surfaces resist quench cracking and have good fatigue life because the resulting surfaces have __ residual stresses.
  136. Stainless steels have good corrosion resistance because of the:
    Adherent oxide layer that forms on the surface
  137. In order to be considered as a true stainless steel, an iron-based metal must contain more than:
    12% chromium
  138. This type of stainless can contain sighificant amounts of carbon and achiebes musch of its strength from phase transformation hardening.
  139. This family of stainless steel is the cheapest, and it achieves most of its strength from solid solution strengthening.
  140. This type of stainless can be easily identified and separated from the other tupes since it is not strongly attracted to a magnet.
  141. The family of stainless steels that offers the greatest ductility and formability (because of its FCC crystal structure) is:
  142. Cast irons are alloys of:
  143. The best ductility and fracture resistance are observed in this type of iron where smooth-surface graphite sheres form directly upon solidification.
    • Ductile
    • Mag thrown in
  144. This type of cast iron is used almost exclusively for wear-resistance applications. It is extremely hard and brittle because the excess carbon is all in the form of Fe3C.
  145. Compacted graphite cast iron has a structure and properties that are intermediate between ___ and ___.
    Gray and ductile
  146. Graphite "flakes" are the characteristic feature that idenities ___ cast iron.
  147. The type of cast iron that uses a long-time, elevated-temperature heat treatment to produce graphite clumps is:
  148. A cast iron alloy contains 2.8% carbon, 1.8% silicon, 1% chromium, and 1% nickel. Its carbon equivalent is:
    • 3.4%
    • C~=C+Si/3
  149. Having completed this third hour exam, I can honestly say:
    • I'm glad I looked at the back exams - 95% of the questions were direct lifts!
    • I wish I had spent a bit more time studying the file material -ouch!
    • I'll never uderstand all of those structure "ites", regardless of how much I study!
    • "I'll never need to uderstand steel - everythings's going to be made from plastic!"
  150. Which of the following is not an attractive asset of aluminum and aluminum alloys?
    Easy to fabricate
    Very ductile
    Good wear, creep, and fatigue properties
    Good electrical and thermal conductivity
    Good wear, creep, and fatigue properties
  151. The corrosion resistance of aluminum is attributed to:
    An adherent protective oxide, much like stainless steel
  152. For aluminum alloys, the highest strength is achieved through:
    Age hardening
  153. The best corrosion resistance would be found in ___ aluminum alloys
    Non-age hardening (single phase)
  154. In the aluminum alloy designation 7075-T6, the T6 suffix denotes the:
    Past processing history
  155. Magnesium alloys are designated by a:
    Two letter, two number sequence (AZ91)
  156. Compared to aluminum, magnesium alloys are:
  157. This is the ony lightweight metal that is also considered to be an "elevated temperature" material, retaining useful strength up through 500C or 900F.
  158. Which of the following lightweight metals would be capable of possessing the highest strength?
  159. This lightweight metal is unique in being lighter than aluminum, but stiffer tahn steel. Unfortunately it is also brittle and sometimes considered to be toxic.
  160. Users of this metal are often willing to accept its negative properties and characteristics in order to gain the weight savings offered by this lightest of the engineering metals.
  161. Copper and copper alloys are msot often used for their:
    Conductivity and corrsosion resistance
  162. When we need useful strength and corrosion resistance at elevated temperature, we might want to consider:
    Nickel alloys
  163. The nickel-base alloy that has been described as having "better corrosion resistance to more media than any other commercial alloy" is:
  164. The superalloy metals are usually based on which two metals?
    Nickel and cobalt
  165. The upper limit to the practical application of the refractory metals is closest to:
    3000F (1700C)
  166. The upper limit to the application of the supperalloy metals is closest to:
    2000F (1100C)
  167. Which of the following ould be considered to be a refractory metal?
  168. Which of the following is not a characteristic property of ceramic materials?
    Good electrical and thermall conductivity
  169. The bonding in ceramic materials is:
    Ionic and convalent
  170. Since glass is a(n) ___ structure, ist formation requires a cooling rate ___ than some critical value.
    Nonequilibrium, Faster
  171. The crystalline ceramics anre brittle because:
    Fracture occurs at a lower stress than dislocation mevenment
  172. A metal matrix provides toughness and fracture resistance in:
  173. Tempered glass acquires its fracture resistance through:
    Compressive residual stresses
  174. The uuses and applications of ceramic materials are usually dominated by their:
    Physical properties (Physics 24)
  175. The excellent high temperature properties of ceramic materials make them excellent candidate materials for use as:
  176. Nominally "identical" ceramic products often fail at widely different mechanical loads becasue:
    Variation in flaw size and location
  177. Which of the following properties is not an asset of polymeric materials?
    High strength and rigidity (stiffness)
  178. In our "cotten ball" model of linear polymers, the bonding within the fibers would be ___, with the bonding between the molecular fibers being ___.
    Convalent, vanderWaals
  179. The recyclable polymers are almost always:
  180. Three-dimensional network polymers form when the reacting mers have a functionality of:
    Three or more
  181. Which of the following is not likely to increase the strength of a linear thermoplastic polymer?
    • Initiate branching
    • 90 and brake and push others apart
  182. When fabbricating products from thermoplastics polymers, production may be slowe becasue we must:
    Wait for the polymer to cool in the mold before is can be ejected
  183. The linear moecules in this tupe of polymer act like coilded springs, uncoiling and recoiling with the application and removal of the mechanical loads. A good example is a rubber band.
  184. In general, the stiffest (most rigid) polymers have an elastic modulus that is:
    Considerably inferior to metals
  185. Which of the follwoing is not an attractive feature of adhesive bonding?
    Adhesives are light in weight
    The joints offer good strength at elevated temperatures (in excess of 500F)
    All the materials and combinations can be joined
    Joints can be formed at low temperatures (often room temp)
    • The joints offer good strength at elevated temperatures (in excess of 500F)
    • They can really only go up to 350F
  186. Which of the following is not a correct statement regarding composite materials?
    Composite materials can be easily separated and recycled
    Distinct interfaces are present betweeen the component materials
    The components can be metals, ceramics, polymers, or even natural materials
    Each component retains its identity, structure and properties
    Composite materials can be easily separated and recycled
  187. Because of their geometries, the properties of ___ composites are ALWAYS ANISOTROPIC, while the properties of ___ composites are ALWAYS ISOTROPIC.
    Laminar; Particulate
  188. In fiber-reinforced composites, the term "specific strength" refers to the ratio of:
    Tensile strength to density
  189. The aspect ratio of a reinforcing fiber is the ratio of its:
    Length to diameter
  190. In a fiber-reinforced composite, we ask the matrix material to do all of the following except:
    Probide ductility and toughness
    Probide strength and stiffness
    Supposrt the fibers
    Probide desired electrical or thermal conductivity
    Provide strength and stiffness
  191. Which of the following is not a significant limitation to the use of fiber-reinforced composites?
    They have poor stiffness and fatigue life
    Difficult to repair
    Difficult to inspect
    Joining is severely limited
    They have poor stiffness and fatigue life
  192. The Rule of Mixtures predicts properties based on:
    The volume fractions of the component materials
  193. The highest operating temperatures in te fiber-reinforced composites can be achieved with a ___ matrix
  194. According to the government studies on corrosion, about ___% of allcorrosion could have been avoided at no additional cost - the ignorance or stupidity factor.
  195. In a galvanic corrosion cell, corrosion occurs at the __ where electrons are ___.
    Anode, Created
  196. The current U.S. penney is copper plated zinc. If the copper plating is somehow ruptured or scatched through, the subsequent corrosion will occur in the:
  197. In an oxygen concentration corrosion cell, the accelerated corrosion occurs in the material adjacent to the:
    Low concentration of oxygen
  198. The corrosion resistance that is imparted by zinc coating steel (galvanizing) is achieved by the mechanism of:
    A sacrificial anode
  199. Based on what I've learned in Met. 121--
    • "I still think mag wheels would be cool on my daily-driver! I'll be careful parking"
    • I can now get a job installing aluminum siding on houses - Good backup to my S&T degree.
    • I know why I don't want a glass or ceramic fry pan - especially if it's my night to do the dishes!
    • I'll be suspicious when the tabloids announce the finding of an aluminum-skinned UFO - HINT - ability to endure high temperatures of atmosphere entry?