Failure and Strengthening in Material Processing
Failure and Strengthening in Material Processing

Failure and Strengthening in Material Processing

Lead Author(s): Saylor Academy

Source: Saylor

Student Price: FREE

A question pack on materials and material processing in engineering.

This content is licensed under the Creative Commons Attribution 3.0 Unported License.

Failure and Strengthening in Material Processing Q1

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.

Failure and Strengthening in Material Processing Q10

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

A

annealing.

B

straining.

C

melting.

D

strengthening.

Failure and Strengthening in Material Processing Q11

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.

Failure and Strengthening in Material Processing Q12

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.

Failure and Strengthening in Material Processing Q13

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.

Failure and Strengthening in Material Processing Q14

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.

Failure and Strengthening in Material Processing Q15

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.

Failure and Strengthening in Material Processing Q16

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

Failure and Strengthening in Material Processing Q17

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.

Failure and Strengthening in Material Processing Q18

“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.

Failure and Strengthening in Material Processing Q19

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.

Failure and Strengthening in Material Processing Q2

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.

Failure and Strengthening in Material Processing Q20

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.

Failure and Strengthening in Material Processing Q21

Creep deformation is particularly a concern

A

when corrosion is occurring.

B

at low temperatures.

C

at high temperatures.

D

when vibration is present.

Failure and Strengthening in Material Processing Q22

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.

Failure and Strengthening in Material Processing Q23

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.

Failure and Strengthening in Material Processing Q24

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.

Failure and Strengthening in Material Processing Q25

To predict fast fracture, materials are compared in terms of

A

critical stress intensity factor.

B

hardness number.

C

density.

D

melting temperature.

Failure and Strengthening in Material Processing Q26

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.

Failure and Strengthening in Material Processing Q27

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

Failure and Strengthening in Material Processing Q29

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

Failure and Strengthening in Material Processing Q3

A “critical crack length” is associated with

A

plastic yielding

B

creep permanent strain.

C

fast fracture.

D

non‑protective oxide films.

Failure and Strengthening in Material Processing Q30

With electrochemical attack, the dissolving metal is

A

more dense metal.

B

the standard electrode.

C

the cathode.

D

the anode.

Failure and Strengthening in Material Processing Q31

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.

Failure and Strengthening in Material Processing Q32

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.

Failure and Strengthening in Material Processing Q33

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.

Failure and Strengthening in Material Processing Q4

Creep deformation failure is a concern

A

in jet engines.

B

in automobile engines.

C

with aircraft wings.

D

with plastics at low temperatures.

Failure and Strengthening in Material Processing Q5

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.

Failure and Strengthening in Material Processing Q6

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.

Failure and Strengthening in Material Processing Q7

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.

Failure and Strengthening in Material Processing Q8

Linear oxidation rates are associated with

A

brittle fracture.

B

protective oxide films.

C

non‑protective oxide films.

D

stainless steels.

Failure and Strengthening in Material Processing Q9

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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