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ISAT 430 Materials Processing Name______________________________ Spring 2001 Prof. G. Kenneth Lewis, Jr. Hourly Examination No.
Please read carefully. Look over the whole exam before you begin. There may be formulae on the back page. Know what you are facing before you start.
Units will be needed so where appropriate, please use them. You must not just write down answers. You need to show your work. If I cannot follow your path of reasoning, you will NOT like the result. Your work must also be legible and neat. If I cannot read or understand your sterling line of attack, you, once again, will NOT like the result.
Part Maximum Score
Score
Multiple. Choice
400
Problems. 41 20 42 24 43 30 Total 474
I have neither given nor received help on this test. ________________________________ Signature
And now, carry on!
The first part is multiple choice. (10 points each)
- In the elastic region of a stress strain curve, a. Stress is inversely proportional to strain
b. Stress is directly proportional to strain.
c. Stress is an exponential function of strain d. Stress is just a state of mind
- At the maximum stress a. The material begins to yield b. The material always fails c. The elastic limit has been reached
d. The material may fail depending on the type of
material.
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- The amount of strain that a material can endure before rupture is a measure of its a. Brittleness
b. Ductility
c. Hardness d. Degree of crystallinity
- Which of the following types of stress – strain relationship best describes the behavior of a brittle material such as a ceramic? a. Elastic and perfectly plastic b. Elastic and strain hardening
c. Perfectly elastic
d. None of these
- Which of the following types of stress – strain relationship best describes the behavior of most metals at room temperature? a. Elastic and perfectly plastic
b. Elastic and strain hardening
c. Perfectly elastic d. None of these
- Which of the following types of stress – strain relationship best describes the behavior of metals at temperatures above their respective recrystallization temperatures
a. Elastic and perfectly plastic
b. Elastic and strain hardening c. Perfectly elastic d. None of these
- Which of the metallic elements listed below is the most abundant? a. Aluminum b. Copper
c. Silicon
d. Magnesium e. Iron
- The predominant phase in the iron carbon alloy system for a composition of 99.0% Fe at room temperature is
a. Alpha ferrite
b. Austenite c. Cementite d. Gamma iron
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c. Maybe d. Sorta
- Which of the following reinforcing geometries offers the greatest potential for strength and stiffness improvement in the resulting composite material?
a. Fibers
b. Flakes c. Particles d. Chopped fibers e. Rice krispies
- Which of the following metal is used as the matrix metal in nearly all WC cemented carbides? a. Tungsten b. Aluminum
c. Cobalt
d. Titanium e. Lead
- Which of the following polymer types is the most commonly used in polymer reinforced plastics? a. Elastomers b. Thermoplastics
c. Thermosets
d. Sodium chloride
- Ceramic matrix composites are designed to overcome which primary weakness in ceramics? a. Hardness b. Hot hardness
c. Toughness
d. Modulus of elasticity e. Tensile strength
- In foundry work, a runner is which one of the following?
a. A channel I the mold leading from the sprue to
the main mold cavity.
b. A foundry-man who moves the molten metal to the mold c. A vertical channel into which molten metal is poured into the mold. d. The long cable to which the cast parts are clipped after removal from the mold.
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- The upper half of a sand casting mold is called the
a. Cope
b. Drag
- During solidification of an alloy when a mixture of solid and liquid metals are present, the solid—liquid mixture is referred to as which one of the following? a. Eutectic composition b. Ingot segregation
c. Slushy zone
d. Liquidus e. solidus
- In casting, the flask is a. A beverage bottle for the foundry-man
b. The box that hold the cope and drag
c. A container for holding liquid metal d. The metal that sometime extrudes between mold halves.
- The term “green piece” in ceramics refers to a part that has been shaped but not fired.
a. Yes
b. No c. Maybe d. Save the Whales
- Which of the following terms, best describes what a cemented carbide is/
a. Composite
b. Ceramic c. Metal d. Cermet
- Which of the following qualifies as a precision casting process? a. Sand casting
b. Investment casting
c. Plaster casting d. None of the above.
- Which of the following casting materials is the most important commercially? (meaning most tonnage) a. Aluminum and its alloys b. Cast iron
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d. Chromizing e. Nitriding
- The first bronze cannon was
a. Made by a monk
b. Shot at a monk c. Bought by a monk d. Prayed over by a monk e. None of the above
- A eutectic mixture
a. Melts at a single temperature
b. Is always solid c. Is only found in iron – carbon alloys d. Has a separate liquidus and solidus
- Anywhere above the liquidus line a. The material consists of both a liquid and a solid
b. Is purely liquid
c. Is purely solid d. Is unstable e. Is totally knarly
- In sand casting, the basic ingredients are
a. SiO2 and a clay binder
b. SiO 2 and a light oil c. Al 2 O 3 and a clay binder d. SiO 2 and Al 2 O 3 and a light oil e. None of the above
- If one assumes that the radius of a circle is equal to the distance from the origin to the coordinates, x = 3, y = 4, then the area A of the circle so defined is a. 50.
b. 78.
c. 28. d. 102. e. all the above
- The extreme Martensitic hardness comes from the
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a. Addition of more carbon into the lattice
b. Lattice strain created by the carbon trapped in
the body centered tetragonal lattice
c. Internal tension caused by the resulting huge grain boundaries d. Resultant Cementite formation
38. If one knows the coordinate points x, and y and the angle θ that a
line from the origin to the coordinate points makes, then one may immediately express the area of the circle defined as: sin cos
xy A
a. Yes!
b. What???? c. No!
- Surface hardening is a “thermo-chemical” treatment whereby the surface is altered by a. The quick quenching of the part resulting in residual surface stresses
b. The addition of carbon, nitrogen, which changes
the surface alloy
c. The annealing out of stresses to bring the part to “thermo- chemical” equilibrium. d. All the above
- The increase in CMC toughness is caused by a. Crack deflection b. Crack propagation stoppage c. Fiber bridging d. Fiber pullout
e. All the above
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b. (5 points) What is the composition of the liquid?
At this point, the first liquid will have the composition shown by drawing a line to the left to where it touches the liquidus line. This composition is ~28 wt% Ni.
c. (5 points) What is the composition of the solid?
The composition of the solid just as we touch the solidus line will still be 40 wt%
d. (5 points) At what temperature is the last metal melted?
We continue up the vertical 40% line. When the temperature hits the liquidus line, all is melted. This temperature is ~1284°C
- Consider the piece of the Fe—C phase diagram shown below. a. (24 points) Describe the material at points A, B, and C. That is, what is the solid (if any) what is its composition? What is the liquid (if any) what is its composition?
Write neatly please
At point A, there will be liquid (~2.9% C) and gamma iron (~1.2% C
At point B, there will be a solid solution of gamma iron with ~1.9% C
At point C, there will be a solid solution of gamma iron (~1.1% c) and Fe 3 C.
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C
B
A
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Some equations and data for you…..
Area of a sphere = 4 3 3
π r
Avagadro’s Number = 6.023x10^23 atoms/g atom
Weight of one diLithium crystal (battle cruiser grade) = 43,244 kg
Normal body temperature = 98.6°F
1 Pa = 1.45 x 10-4^ psi
There are 4.48 Newtons in a pound
There are 24 Fig Newtons in a box.
Here is some data: 2, 3, 2.3, 3, 3, 4, 1, 2.6, 3
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