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Materials Processing: Test 1 - Chapters 10, 11, 12 & Lost Foam Casting - Spring 2011 - Pro, Exams of Mechanical Engineering

Georgia Southern University (GS)Mechanical Engineering
Prof. David Williams

A test for the materials processing course focusing on chapters 10, 11, 12, and lost foam casting. The test includes multiple-choice and short answer questions covering topics such as the properties of pure metals, solidification process, casting considerations, and casting defects.

Typology: Exams

2010/2011

Uploaded on 05/10/2011

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TMET – 3343
MATERIALS PROCESSING
Test 1 Chapters 10, 11, 12 & Lost Foam Casting Spring 2011
PART I INSTRUCTIONS: Best Answer – Select the answer that best answers or completes the
item and circle the letter of your choice.
1. Pure metals have clearly defined freezing (melting) point that: (238/10.2.1/1)
a. Approaches zero (is a constant temperature)
b. Can produce a paste like zone that moves as a frontal plane during solidification
c. Produces grain sizes and distribution that lacks uniformity
d. All of the above
2. The sequence of “events” that takes place in the solidification phase in a casting mold
influences the size, shape, uniformity, and chemical composition of the grains formed
throughout the casting, and thus the reason that control of the solidification process is so
important. (238(10.2).1.2)
a. True
b. False
3. Which of the following items is NOT one of the three Important Considerations in
casting operations, as identified in your text? (237/10.1/1)
a. The flow of the molten metal into the mold cavity
b. The solidification and cooling of the metal in the mold
c. Anisotropic properties of the metal
d. Influence of the type of mold material
4. The capability of a molten metal to fill a mold cavity is called its: (245/10.4/1)
a. Fluidity c. Flow rate
b. Inclusion d. Viscosity
5. The initial cooling of metal in a mold (assuming no nucleating agents are used) creates a:
(239.1.2)
a. Shell/skin of columnar crystals at the mold walls
b. Shell/skin of equiaxed grains at the mold walls
6. The solidified shell/skin of grains produced closest to the mold walls consists of : (239.1.2)
a. Fine grains
b. Coarse grains
7. The heat transfer rate at the mold walls produces: (fig. 10.2)
a. A chill-zone
b. Latent solidification that produces course grains
c. “slow cooling”
d. All of the above
8. As the solidification of the casting progresses away from the mold walls (toward the
center of the mold), the next grains that are formed tend to be: (fig 10.3)
a. Columnar
b. Equiaxed
9. Equiaxed grains: (50 (1.6).1)
a. Are grains with equal dimensions in all directions
b. Grains with an elongation in the direction of cooling
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Download Materials Processing: Test 1 - Chapters 10, 11, 12 & Lost Foam Casting - Spring 2011 - Pro and more Exams Mechanical Engineering in PDF only on Docsity!

MATERIALS PROCESSING

Test 1 Chapters 10, 11, 12 & Lost Foam Casting Spring 2011

PART I INSTRUCTIONS: Best Answer – Select the answer that best answers or completes the item and circle the letter of your choice.

  1. Pure metals have clearly defined freezing (melting) point that: (238/10.2.1/1) a. Approaches zero (is a constant temperature) b. Can produce a paste like zone that moves as a frontal plane during solidification c. Produces grain sizes and distribution that lacks uniformity d. All of the above
  2. The sequence of “events” that takes place in the solidification phase in a casting mold influences the size, shape, uniformity, and chemical composition of the grains formed throughout the casting, and thus the reason that control of the solidification process is so important. (238(10.2).1.2) a. True b. False
  3. Which of the following items is NOT one of the three Important Considerations in casting operations, as identified in your text? (237/10.1/1) a. The flow of the molten metal into the mold cavity b. The solidification and cooling of the metal in the mold c. Anisotropic properties of the metal d. Influence of the type of mold material
  4. The capability of a molten metal to fill a mold cavity is called its: (245/10.4/1) a. Fluidity c. Flow rate b. Inclusion d. Viscosity
  5. The initial cooling of metal in a mold (assuming no nucleating agents are used) creates a: (239.1.2) a. Shell/skin of columnar crystals at the mold walls b. Shell/skin of equiaxed grains at the mold walls
  6. The solidified shell/skin of grains produced closest to the mold walls consists of : (239.1.2) a. Fine grains b. Coarse grains
  7. The heat transfer rate at the mold walls produces: (fig. 10.2) a. A chill-zone b. Latent solidification that produces course grains c. “slow cooling” d. All of the above
  8. As the solidification of the casting progresses away from the mold walls (toward the center of the mold), the next grains that are formed tend to be: (fig 10.3) a. Columnar b. Equiaxed
  9. Equiaxed grains: (50 (1.6).1) a. Are grains with equal dimensions in all directions b. Grains with an elongation in the direction of cooling

MATERIALS PROCESSING

Test 1 Chapters 10, 11, 12 & Lost Foam Casting Spring 2011

  1. According to your text, columnar grains have ‘favorable orientation and grow preferentially’ meaning they grow in a direction that is opposite of heat transfer during the cooling cycle. (239.1.4) a. True b. False
  2. Slow cooling rates: (241.2.1) a. Produce course dendrites with large spacing between the ‘dendrite arms’ b. Produce fine dendritic structure with large spacing of the ‘dendrite arms’ c. Produce an amorphous structure
  3. Alloys have a freezing (melting) range (T (^) L – T (^) S) that: (238/10.2.1/1) a. Approaches zero (is a constant temperature) b. Can produce a paste like zone that moves as a frontal plane during solidification c. Develops grains through the process of homogeneous nucleation d. Both answers B & C above are true
  4. Very fast cooling rates, especially in alloys containing, boron, silicon, phosphorus, etc. produces: (241.2.3) a. Amorphous structure b. Fine equiaxed grain structure c. Very course dendritic grain structure
  5. As grain size decreases: (241.3.2) a. Cast alloy strength and ductility increases b. Micro-porosity decreases c. Tendency for cracking decreases d. All of the above
  6. The purpose of using inoculants in the casting process is to: (242.4.2) a. Extend the inner zone of equiaxed grain formation throughout the casting b. Induce nucleation c. Promotes heterogeneous nucleation d. All of the above
  7. Some metals can have an amorphous structure, they are called: (Ch10.ppt) a. Eutectics b. Metallic glasses c. Inter-dendritic alloys d. None of the above
  8. Which of the following is NOT one of the sequential events that produce shrinkage in a casting? (248(10.5.2)) a. Contraction of the molten metal as it cools prior to its solidification b. Contraction that produces inter-granular segregation during solidification c. Contraction of the molten metal during the phase change from liquid to solid d. Contraction of the solidified metal (the casting) as in cools
  9. Anisotropic properties of cast alloys influence both mechanical and physical properties of the alloy. (Ch10.ppt) a. True b. False

MATERIALS PROCESSING

Test 1 Chapters 10, 11, 12 & Lost Foam Casting Spring 2011

A. B. C.

  1. Identify, from the diagram above which is representative of the solidified structure of a pure metal. a. columnar zones only b. Columnar rim with an equiaxed zone in the “middle” c. Equiaxed structure
  2. Identify, from the diagram above which is representative of the solidified structure obtained by using a nucleation agen t. a. columnar zones only b. Columnar rim with an equiaxed zone in the “middle” c. Equiaxed structure
  3. Identify, from the diagram above which is representative of a solid solution alloy. a. columnar zones only b. Columnar rim with an equiaxed zone in the “middle” c. Equiaxed structure
  4. Micro -segregation –basically can be described as “coring”. a. True b. false
  5. Which of the following is a description of gravity segregation? a. higher density inclusions or compounds sink and lighter elements float b. coring c. composition differences occur throughout the casting itself d. none of the above
  6. Which of the following industries leads in the use of evaporative-pattern casting? a. jewelry industry b. cast iron foundries that manufacture fire hydrants c. automotive parts d. dental laboratories

MATERIALS PROCESSING

Test 1 Chapters 10, 11, 12 & Lost Foam Casting Spring 2011

  1. Investment casting is also widely known as______?_______ casting in the jewelry industry and dentistry: a. lost-foam b. lost-wax
  2. Which of the following sands used in traditional sand casting uses oil as a binding agent? a. green sand b. synthetic sand c. Both of he above use oil as a binding agent.
  3. Draft , as it is used in the context of sand casting, is: a. a parting agent to allow a flask to be separated at the parting line b. a component in the runner system that controls flow of metal into the mold cavity c. a reservoir of metal that supplies additional metal as a casting shrinks d. tapered vertical surfaces of a pattern so the pattern can be extracted from a mold
  4. Which casting technique makes use of a mixture of sand and (2.5 - 4%) plastic resin to produce the mold for subsequent casting? a. rammed graphite molding c. plaster mold casting b. ceramic mold casting d. shell molding

PART II INSTRUCTIONS: Short Answer – Write a brief answer/description that addresses the following items. Stay to the point and you may use a sketch to help illustrate if you choose.

  1. Define the terms ‘ chill’ as it relates to its use in the sand casting process.
  2. Define Reynolds Number and describe its use in the casting process. Discuss in terms of turbulence ‘vs’ laminar flow [include flow rate values (numbers), formula, etc. that are appropriate to illustrate this]
  3. What tool is used, when making a pattern to be used in a sand casting mold, so that the pattern compensates for shrinkage?
  4. What is sodium silicate and how it used in the core making process in sand casting?