A creep resistant material should have

	a. a high elastic modulus.
	b. a high melting temperature.
	c. a high yield strength.
	d. a long fatigue life.

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A material has a melting point of 200 degrees Celsius, and we apply constant force loads at 20 degrees Celsius.

	a. We do not expect creep deformation to occur.
	b. Fast fracture should occur before creep deformation begins.
	c. We do expect creep deformation to occur.
	d. We do not have enough information to predict creep deformation.

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A “critical crack length” is associated with

	a. plastic yielding
	b. creep permanent strain.
	c. fast fracture.
	d. non-protective oxide films.

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A “ductile” material has a relatively high value of

	a. percent elongation.
	b. hardness.
	c. elastic modulus.
	d. ultimate tensile strength.

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A “stiff” material has a relatively high value of

	a. elastic modulus.
	b. Poisson’s ratio.
	c. yield stress.
	d. tensile strength.

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A “strong” material has a relatively high value of

	a. shear modulus.
	b. yield stress.
	c. percent elongation.
	d. creep rate.

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Charpy and Izod are names associated with equipment used to measure

	a. hardness.
	b. yield strength.
	c. creep resistance.
	d. toughness.

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Creep deformation failure is a concern

	a. in jet engines.
	b. in automobile engines.
	c. with aircraft wings.
	d. with plastics at low temperatures.

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Creep deformation is particularly a concern

	a. at low temperatures.
	b. at high temperatures.
	c. when vibration is present.
	d. when materials are in an oxygen-rich environment.

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Failure by nucleation of surface cracks is particularly common with

	a. impact testing.
	b. fatigue testing.
	c. creep testing.
	d. tensile testing.

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Fast fracture

	a. is crack propagation at the speed of sound.
	b. is always preceded by plastic yielding.
	c. occurs only at low temperatures.
	d. is observed in ceramics, but never in metals.

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For ductile metals that strain harden, the tensile strength

	a. may be either less than or greater than the yield stress.
	b. is always less than the yield stress.
	c. is always greater than the yield stress.
	d. is not usually measured in the tensile test.

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For most solids (metals, ceramics, rigid plastics) elastic deformation

	a. is linear stress-strain behavior.
	b. is parabolic stress-strain behavior.
	c. obeys the Arrhenius law.
	d. results in permanent shape change.

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Hardness measurements

	a. can identify polymers.
	b. are completely non-destructive.
	c. cannot be made on ceramics.
	d. often follow heat treatment of metals.

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Hardness measurements are useful because the resulting hardness number can be correlated with the material property of

	a. yield stress.
	b. creep rate.
	c. fatigue life.
	d. stiffness.

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Linear oxidation rates are associated with

	a. brittle fracture.
	b. protective oxide films.
	c. non-protective oxide films.
	d. stainless steels.

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Materials described as “ductile”

	a. have low melting points.
	b. have a high percent elongation.
	c. have a low yield stress.
	d. have low percent area reduction values.

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Oxidation of metals

	a. is always corrosive.
	b. can sometimes be beneficial.
	c. doesn’t occur with many metals.
	d. can be avoided by operating at high temperatures.

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Plastic deformation

	a. only occurs at elevated temperatures.
	b. is irreversible shape change.
	c. can sometimes be reversible shape change.
	d. always fractures the part.

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Preexisting micro cracks such as those found in sintered materials and large welded structures tend to promote failure by

	a. fast fracture.
	b. plastic yielding.
	c. excessive creep strain.
	d. non-protective oxide formation.

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Rockwell and Brinell are names associated with equipment used to measure

	a. stiffness.
	b. hardness.
	c. toughness.
	d. fatigue life.

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Some metals exhibit an “endurance limit” when loaded

	a. in a tensile test.
	b. in a fatigue test.
	c. in a creep test.
	d. in a hardness machine.

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Sometimes we do not try to stop electrochemical attack, but allow it to proceed by

	a. using materials with parabolic oxide growth rates.
	b. utilizing a sacrificial cathode.
	c. utilizing a sacrificial anode.
	d. using materials with linear oxide growth rates.

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The Arrhenius law is often found to describe

	a. final hardness.
	b. cycles to failure.
	c. impact strength.
	d. temperature variations.

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The label of “hardening” is often used to describe the process of

	a. annealing.
	b. straining.
	c. melting.
	d. strengthening.

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The sliding deformation of shear

	a. always results in a decrease in volume.
	b. occurs with constant volume.
	c. always results in an increase in volume.
	d. can either increase or decrease the volume.

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The Standard Electrode Potential and Galvanic Series give information about

	a. wet corrosion rates.
	b. protective oxide films.
	c. cathode and anode identification.
	d. corrosion electrical currents.

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The units of mechanical stress are

	a. meters squared (or feet squared).
	b. dimensionless.
	c. newtons/meters squared (or pounds per square inch).
	d. newtons (or pounds).

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The units of Poisson’s ratio are

	a. pascals.
	b. seconds.
	c. meters squared.
	d. dimensionless.

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The units of the stress intensity factor are

	a. pascals.
	b. pascals times square root of meters.
	c. percent per square meter.
	d. dimensionless.

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The units plotted on an S-N curve are

	a. stress versus cycles.
	b. stress versus strain.
	c. strain versus time.
	d. mass gain versus time.

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To minimize the rate of wet corrosion we should

	a. minimize the cathode area.
	b. minimize the anode area.
	c. make the anode and cathode areas as nearly equal as possible.
	d. ignore areas as corrosion rate is not strongly dependent on area.

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Which of the following promotes longer fatigue life?

	a. Residual tensile stresses in the surface
	b. Sharp corners in the sample geometry
	c. Rough surface texture
	d. Residual compression stresses in the surface

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With surface treatments to a material, we can significantly

	a. decrease creep strain rate.
	b. increase stiffness.
	c. increase impact energy absorption.
	d. lengthen fatigue life.

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“Brittle” materials exhibit

	a. plastic deformation followed by elastic deformation.
	b. elastic deformation followed by plastic deformation.
	c. elastic deformation only.
	d. plastic deformation only.

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“Strain Hardening” refers to

	a. necking down of polymer materials.
	b. a property of brittle materials.
	c. an increase in yield stress.
	d. an increase in stiffness.

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A disadvantage of aluminum alloys is that they

	a. show creep deformation at relatively low temperatures.
	b. oxidize rapidly.
	c. cannot be alloyed to be heat treatable.
	d. have low thermal conductivity.

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A disadvantage of ceramics is they

	a. often interact with atmospheres.
	b. can be difficult to shape.
	c. tend to deform by creep.
	d. lose their ductility at low temperatures.

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A disadvantage of titanium alloys is that

	a. they are relatively expensive.
	b. they are chemically reactive.
	c. they have high strength to weight ratios.
	d. they cannot be heat treated.

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An advantage of ceramics is that

	a. they are typically very hard.
	b. they can easily be formed into complex shapes.
	c. they have high percent elongation.
	d. they have high densities.

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An advantage of polymers is that

	a. they usually have high melting temperatures.
	b. they are hard and scratch resistant.
	c. they have low elastic modulus values.
	d. they are usually chemically inert.

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At the glass transition temperature, thermoplastic polymers

	a. show a volume change like melting ice.
	b. change color.
	c. change smoothly between rigid solid and viscous liquid.
	d. permanently set up into rigid solids.

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Cermets are composites of ceramic and metal. We would expect the resulting material to be

	a. brittle and electrically insulating.
	b. tough and hard.
	c. flexible and high melting.
	d. low density and soft.

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Covalent bonds

	a. result in ions packing close together.
	b. are consistent with the high electrical conductivity of metals.
	c. are easily broken during plastic deformation.
	d. result in lower density solids.

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Cross-linking a thermoplastic polymer

	a. stiffens it.
	b. causes it to flow more freely.
	c. increases the glass transition temperature.
	d. improves oxidation resistance.

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During the “tempering” process of quench hardened steels

	a. a hard, strong phase forms.
	b. the steel softens slightly.
	c. oxide formation is reduced.
	d. the operating temperature of the final steel product is increased.

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Engineering composites are often GRPR and CRPR, with the PR standing for

	a. polycrystalline reinforced.
	b. particle remelted.
	c. polymer resins.
	d. plastic remolded.

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Low carbon or mild steels

	a. are always quench hardened.
	b. are the construction I-beam steels.
	c. have particularly good corrosion resistance.
	d. have relatively large amounts of other alloying elements.

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Metals that exhibit high thermal conductivity generally

	a. have low densities.
	b. have high melting temperatures.
	c. exhibit low electrical conductivity.
	d. also exhibit high electrical conductivity.

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Most often, engineering composites are chosen for

	a. isotropic behavior (same in all directions).
	b. light weight.
	c. high melting temperature.
	d. low cost.

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Oxides, nitrides, and silicates predominate in

	a. polymers.
	b. ceramics.
	c. composite materials.
	d. metals.

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Some polymers are rubbery because

	a. covalent bonds readily stretch.
	b. long chain molecules can uncoil and recoil.
	c. polymer molecules easily slide over one another.
	d. ionic bonds are easily broken.

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The nature of metallic bonding accounts for

	a. the light weight of some metals.
	b. the high electrical and thermal conductivities of most metals.
	c. the tendency of metals to corrode.
	d. the brittleness of some metals.

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The quench process in precipitation-hardened alloys

	a. results in a hard structure.
	b. results in a soft structure.
	c. causes a phase change within the alloy.
	d. is required to clean the alloy surface.

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Thermoplastic polymers

	a. are rubbery materials.
	b. are permanent once cured.
	c. are usable to higher temperatures than other polymers types.
	d. can be repeatedly softened and stiffened.

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Thermosetting polymers

	a. are recyclable.
	b. are frequently rubber-like.
	c. include the hard, rigid Bakelite® and melamine plastics.
	d. are usually clear or translucent.

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To operate at the highest temperature, the materials class most often chosen is

	a. composite materials.
	b. metals.
	c. polymers.
	d. ceramics.

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To resist shattering on sudden temperature change, it is desirable that glasses

	a. have low thermal expansion coefficients.
	b. have high thermal expansion coefficients.
	c. have high softening temperatures.
	d. have low densities.

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Which of the following is not a composite material?

	a. Nickel-based super alloy turbine blade
	b. Wood
	c. Reinforced concrete
	d. Graphite reinforced tennis racket frame.

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“Porous” ceramics include

	a. tungsten carbide tool inserts.
	b. porcelain plates.
	c. silicon carbide abrasives.
	d. diamonds.

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A material with a relatively low value of impact energy absorbed

	a. is considered to be ductile.
	b. is considered to be brittle.
	c. is most likely low density.
	d. is most likely of a low melting temperature.

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A predictor of creep deformation is a material’s

	a. endurance limit.
	b. hardness number.
	c. melting or softening temperature in kelvin.
	d. elastic stiffness.

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As a ductile metal is plastically deformed at cooler temperatures

	a. its elastic stiffness increases.
	b. its melting temperature decreases.
	c. its yield stress increases.
	d. its volume increases.

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Crack detection by x-rays or chemical techniques is particularly important if it is suspected that failure might occur by

	a. creep.
	b. plastic yielding.
	c. fast fracture.
	d. oxidation.

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Creep deformation is particularly a concern

	a. when corrosion is occurring.
	b. at low temperatures.
	c. at high temperatures.
	d. when vibration is present.

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For a metal that work hardens severely

	a. the elastic modulus is very low.
	b. the percent elongation is very high.
	c. the tensile strength is much higher than the yield stress.
	d. the tensile strength is much lower than the yield stress.

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Generally we find maximum toughness to fast fracture with

	a. metals.
	b. plastics.
	c. ceramics.
	d. composite materials.

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If a material is to bend before it breaks, a relevant material property is

	a. rupture modulus.
	b. elastic modulus.
	c. hardness number.
	d. percent elongation.

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If elastic deformation is to be a minimum, then

	a. we should select the material with the highest elastic modulus.
	b. we should select the material with the highest melting temperature.
	c. we cannot generalize without knowing the geometry of the part.
	d. we should select the material with the highest yield strength.

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If our part must be light weight, then lacking other design constraints, our choice would most likely be a

	a. plastic.
	b. metal.
	c. ceramic.
	d. composite material.

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Many steels exhibit an “endurance limit” when tested in

	a. creep.
	b. impact.
	c. fatigue.
	d. tension.

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The class of materials stable to the highest temperatures is

	a. metals.
	b. polymers.
	c. composite materials.
	d. ceramics.

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The flexed rotating beam apparatus compares materials in

	a. fatigue failure.
	b. creep failure.
	c. stress corrosion.
	d. elastic recovery.

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The stress-strain curve of an elastomer (rubber-like material) is usually

	a. linear.
	b. non-linear.
	c. restricted to approximately 0.2% strain.
	d. showing a higher elastic modulus than for most metals.

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The units of specific gravity are

	a. kg/m³.
	b. kilograms.
	c. m/s².
	d. dimensionless.

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To minimize creep rate, it is desirable to have metals

	a. with fine (small) grains.
	b. with coarse (large) grains.
	c. with high yield strengths.
	d. with low melting temperatures.

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To predict fast fracture, materials are compared in terms of

	a. critical stress intensity factor.
	b. hardness number.
	c. density.
	d. melting temperature.

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To slow electrochemical attack

	a. the cathode areas should be small.
	b. the anode areas should be small.
	c. metals should be widely separated in the electrochemical series.
	d. surfaces should be rough rather than smooth.

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Which of the following in not a condition for electrochemical attack?

	a. Non-protective oxide film
	b. Contact with an aqueous solution
	c. Electrical contact between anode and cathode
	d. Two dissimilar metals

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Which of the following is not a way to improve fatigue life?

	a. Using polished surfaces
	b. Strain hardening
	c. Introducing compressive surface residual stresses
	d. Reducing geometries of sharp corners

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With electrochemical attack, the dissolving metal is

	a. more dense metal.
	b. the standard electrode.
	c. the cathode.
	d. the anode.

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With fatigue failure, micro cracks grow until the part fails by

	a. creep.
	b. fast fracture.
	c. excessive plastic deformation.
	d. necking down to concentrate stress.

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With galvanized sheet (zinc on steel)

	a. the iron is the sacrificial anode.
	b. the zinc is the sacrificial anode.
	c. either iron or zinc can be the anode.
	d. both the iron and zinc corrode simultaneously.

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“Ductile” materials have

	a. high percent elongation.
	b. low yield strength.
	c. low melting temperatures.
	d. low density.

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A disadvantage of mechanical forming is that

	a. though stronger, final parts are also more brittle.
	b. long rod and tube shapes cannot be formed.
	c. it cannot be used with materials at high temperatures.
	d. porous, low density products may result.

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A disadvantage of sintering is that

	a. parts are generally limited to be small in size.
	b. porous, low-density products may result.
	c. preferred textures may be in the final products.
	d. only low-temperature materials can be formed this way.

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A limitation of forming by casting is that

	a. chemically reacting materials cannot be cast.
	b. extensive post machining may be required.
	c. some materials deteriorate before they melt.
	d. porous, low-density products may result.

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A process capable of forming an intricate geometrical shape is

	a. directional solidification.
	b. preferred orientation stamping.
	c. oxyacetylene torch cutting.
	d. lost wax casting.

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An advantage of forming by casting is

	a. the porous product can be utilized for specialized applications.
	b. dissimilar materials can be joined together.
	c. metals can be strengthened while being shaped.
	d. intricate shapes can be formed in a single step.

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An advantage of forming by mechanical deformation is

	a. dissimilar materials can be joined together.
	b. intricate shapes can be formed in a single step.
	c. the porous product can be utilized for specialized applications.
	d. metals can be strengthened while being shaped.

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An advantage of forming by sintering is

	a. refractory (very high melting) materials can be shaped.
	b. metals can be strengthened while being shaped.
	c. dissimilar materials can be joined together.
	d. preferred texture can be imparted to the final part.

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An advantage of MIG (metal-inert-gas) welding is

	a. dissimilar materials can be joined together.
	b. it can be used to cut as well as join metals.
	c. acetylene gas is explosive.
	d. it can be automated for use with industrial robots.

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Caution must be used with sintering because

	a. very fine powders can be explosive.
	b. large electrical currents pass through the parts.
	c. temperatures involved are higher than the melting temperatures.
	d. corrosive chemicals are required.

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Ceramics are most often shaped by

	a. casting.
	b. sintering.
	c. compressive mechanical forming.
	d. TIG welding.

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Common “stick welding” is more formally known as

	a. MIG welding.
	b. TIG welding.
	c. oxyacetylene welding.
	d. shielded metal arc welding.

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Dislocations in metals are

	a. displaced grain boundaries.
	b. linear geometric defects.
	c. impurity concentrations.
	d. responsible for elastic deformation.

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The heat affected zone in welded stainless steels

	a. refers to the weld filler metal.
	b. is stronger than the surrounding metal.
	c. is severely work hardened.
	d. may no longer be corrosion resistant.

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Thermosetting polymers are frequently shaped by

	a. casting.
	b. extrusion.
	c. TIG welding.
	d. hot rolling.

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When a cold worked metal is annealed,

	a. its yield stress increases.
	b. its fracture toughness is decreased.
	c. recrystallization grows new grains within the metal.
	d. its dislocation density is increased.

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Which statement does not apply to TIG welding?

	a. It frequently is used to cut as well as join.
	b. The tungsten electrode is not consumed during the welding.
	c. TIG requires greater operator skill than other welding processes.
	d. It is usually the first choice for joining stainless steels.

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