MEEN 361 Final Exam Review

In general, which one of the following materials has the highest machinability: (a) aluminum, (b) cast iron, (c) copper, (d) low carbon steel, (e) stainless steel, (f) titanium alloys, (g) unhardened tool steel

(a) aluminum

Which one of the following plate metals produces the hardest surface on a metallic substrate:

(b) chromium

Of all of the current material addition rapid prototyping technologies, which one is the most widely used with hobbyist-level 3D printers utilizing PLA or ABS filament: (a) ballistic particle manufacturing, (b) fused deposition modeling, (c) selective laser intering, (d) solid ground curing, (e) stereolithography

(b) fused deposition modeling

What statements are TRUE for our casting lab? I. Riser is a reservoir for compensation of molten metal for any shrinkage in the casting. II. Sprue is located between the mold cavity and the riser III. Cope is the bottom part for our sand casting flask IV. Pattern is an approximate duplicate of the final casting

* Didn't have a casting lab *

You are given a piece of brass that is cold worked 25% and currently has a cross sectional area of 0.04 in^2. Based on this information, you know the original cross-sectional area in square inches was:

0.053

In a Brinell hardness test, a 1500 kgf load is pressed into a specimen using a 1 cm diameter hardened steel ball. The resulting indentation has a diameter = 0.32 cm. Determine the Brinell hardness number for the metal.

182 BHN

A 20cm long steel rod with a diameter of 20mm is loaded with 5000N weight. If the diameter is reduced to 18mm under this load, determine the engineering strain.

23.5%

A 1020 steel wire is drawn 10% to a diameter of 9mm, and successively further drawn to a diameter of 8mm. Calculate the total percent cold work done on the wire.

28.5%

What process cannot be done by a lathe?

Adding a chamfer to the end of a square cross section or bar of a workpiece

Which of the following will affect the hardenability of steel? I. Amount of alloying II. Quenching medium III. Cooling rate

All of the above

At the back page Figure 1 for the TTT diagram, what line you need to follow for the heat treatment that will give you 50% Pearlite, 50% Martensite?

B

During the metal cutting process, there is a self-excited vibration occurrence, which is called ____.

Chatter

What kind of bond is in the polymer backbone?

Covalent bond

____ is a phenomenon that having small voids during the plastic deformation on polymers which is perpendicular to uniaxial tensile stress direction.

Crazing

The purpose of drilling a pilot hole is to

Ease the drill bit entry into the work piece and prevent drill bit drift and slipping off-center

What is the best way to measure specimen strain during a tensile test? a) An extensometer b) Determine it from cross head displacement and time measurements c) Determine it after specimen fracture providing fracture is within the gage strength d) Either a or b e) From the load versus time data

Either a or b

Which crystal structure is most likely not to exhibit ductile to brittle behavior as the temperature is lowered?

FCC

T/F: Activation energy is the energy which is required to initiate a reaction for recrystallization

False

T/F: All crystalline metals become brittle at very low temperature (~10K)

False

T/F: Amorphous is a crystalline structure

False

T/F: Cementite is a BCC iron

False

T/F: Decreasing the grain diameter increases DBTT

False

T/F: Eutectoid reaction is a reaction wherein, upon cooling, a liquid phase tranforms isothermally and reversibly into two new solid phases that are intimately mixed

False

T/F: It is okay to keep at least two indent diameter spacing between the hardness readings

False

T/F: Material properties are dependent on elemental composition only and not microstructure.

False

T/F: Weld failures always occur in the fusion zone of the weld joint, since this is the part of the joint that has been melted

False

T/F: Welding can only be performed on metals that have the same melting point; otherwise, the metal with the lower melting temperature always melts while the other metal remains solid

False

T/F: When you do annealing, you increase the ductility and the electrical resistivity

False

T/F: You can have viscosity on thermosets if you increase the temperature

False

All of the following are TRUE regarding our machining lab, except which one?

Feed force is a thrust or radial force acting perpendicular to the machined surface

An allow has a composition of 60%B. The microstructure after slow cooling from liquid to room temperature can be described the closest by

Fig (a)

What can NOT be obtained from tensile test data?

Fracture toughness

Which of the following statements are NOT true for recrystallization? I. The smaller the deformation, the lower the recrystallization temperature II. The higher the temperature, the less time required for recrystallization III. the greater the degree of deformation, the smaller the recrystallized grains IV. The larger the original grain size, the less amount of deformation that is required to produce equivalent temperature V. Recrystallization temperature increases with impurity of metals

I, II

Which properties may correlate with hardness values? I. Tensile strength II. Water resistance III. Ductility IV. Young's Modulus

I, II, III

Which of the following statements is/are true for Endurance Limit or Fatigue Limit? I. Certain materials, primarily BCC steels can have endurance limit or fatigue limit II. Stainless steel materials can have endurance limit or fatigue limit III. Austentite low carbon steels can have endurance limit or fatigue limit IV. FCC structure materials can have endurance limit or fatigue limit V. Infinite life for endurance limit is usually defined at 5x10^8

I.

Which of the following processes can increase the yield strength of steel? I. Tempering II. Hot working III. Adding alloying elements IV. Quenching

III, IV

Rank the following in ascending (lowest to highest) order of their hardness (and tensile strength). I. Bainite II. Martensite III. Tempered Martensite IV. Course Pearlite

IV, I, III, II

An increase in the carbon content of plain carbon steel generally does what to the DBTT?

Increases it

What is the result of "Rapid Quenched Steel" after Austentite?

Martensite

Which one of the following will have a highest hardness value?

Medium carbon steel austentized and quenched in water

Which of the following do you believe would characterize a hot-worked steel part in comparison to a cold-worked part? I. Higher Yield Strength II. Better Surface Finish III. Greater Hardness IV. Less Ductility

None of the above

During your heat treatment lab, on the initial stage of the annealing process, there was a small increase on the hardness of your material. It was due to ____.

Polyganization

During cold working, at certain value of thickness dimension reduction there was some degree of increase at the thickness after the rolling. That phenomenon is called ____.

Springback

What can you say about the mechanical properties of material A shown in the plot below?

The DBTT is around 10 to 20 C

When you heated/soaked the bolts for the heat treatment of the steel lab, what was the purpose of the austentizing step?

To dissolve iron carbide (Fe3C)

T/F: A stage of a process that relief of some of the internal strain energy of a previously cold-worked metal is called recrystallization

True

T/F: Bainite is a microstructure that consists of a-Ferrite and a fine dispersion of Cementite

True

T/F: During the hardness test, minor load established reference depth and removes slack from machine

True

T/F: For an alloy system displaying a eutectoid, an alloy for which the concentration of solute is less than the eutectoid composition is called hypoeutectoid alloy

True

T/F: Knurling is performed on a lathe, but it is not a metal cutting operature

True

T/F: There is a good correlation between Brinell hardness and tensile strength for steel

True

Most sheet metalworking operations are performed as which one of the following: (a) cold working, (b) hot working, (c) warm working? Hint: Quality is surface finsh is usually important in sheet metalworking operations

a

In a peritectic reaction, on cooling

a solid phase and a liquid react to form a solid

The difference between the stress-strain behavior of a ductile metal and a thermoplastic polymer above the glass transition temperature is:

a) Polymers exhibit a "drawing" region and metals do not

Choose the structure of Polycarbonate

a) Two hexagons

Which of the following is not a common ingredient in cemented carbide cutting tools (two correct answers): (a) Al2O3, (b) Co, (c) CrC, (d) TiC, and (e) WC

a, c

As an alloying ingredient in high-speed steel, tungsten (i.e. W) serves which of the following functions (select two best answers): (a) forms hard carbides to resist abrasion, (b) improves strength and hardness, (c) increases corrosion resistance, (d) increases hot hardness, and (e) increases toughness?

a, d

Which of the following are advantages and characteristics of hot working relative to cold working (four correct answers): (a) fracture of workpart is less likely, (b) friction is reduced, (c) increased strength properties, (d) isotropic mechanical properties, (e) less overall energy is required, (f) lower deformation forces is required, (g) more significant shape changes are possible, and (h) strain-rate sensitivity is reduced?

a, d, f, g

Which are the most important criteria for the materials selection process of a beverage can? (select only 2) a) loading conditions b) material availability c) price and scalability d) number of manufacturing operations e) recyclability f) corrosion resistance and reactivity with the beverage

a, f

Brittle fracture is characterized by

abrupt (catastrophic) failure with little or no warning

Plain carbon steels are designated in the AISI code system by which of the following: (a) 01XX, (b) 10XX, (c) 11XX, (d) 12XX, (e) 30XX

b)

Which one of the following manufacturing processes will likely result in the best surface finish: (a) arc welding, (b) grinding, (c) machining, (d) sand casting, (e) sawing

b)

In a sand-casting mold, the V/A ratio of the riser should be (a) equal to, (b) greater than, or (c) smaller than the V/A ratio of the casting itself? V/A = Volume to area ratio

b) greater than

Thermal energy is normally associated with which of the following changes in an altered metallic layer (three best answers): (a) cracks, (b) hardness variations, (c) heat affected zone, (d) plastic deformation, (e) recrystallization, or (f) voids?

b, c, e

The following are slip systems in a BCC metal

c) (011)[111-], (101)[111-], (11-0)[111], (110)[1-11]

What statements is/are TRUE about weaknesses of optical microscopy techniques? I. Rarefaction of light through lenses can scatter light and reduce image quality II. Sometimes the electron beam is not focused well by electromagnetic lenses. III. Magnification is limited to light intensity. IV. Only I and III V. All of the above

c) IV.

An outside micrometer would be appropriate for measuring which of the following (two correct answers): (a) hole depth, (b) hole diameter, (c) part length, (d) shaft diameter, (e) surface roughness

c, d

What of the following are two main functions of a cutting fluid in machining (two best answers): (a) improve surface finish on the work piece, (b) reduce forces and power, (c) reduce friction at the tool-chip interface, (d) remove heat from the process, (e) wash away chips?

c, d

Ductile fracture process does NOT involve the following

crack propagates through grains (transgranular fracture)

From the back page Figure 2 for the iron-iron carbide phase diagram, calculate the percent a and Fe3C for steel 1040 (0.4% Carbon content) for the temperature at 726 C, just below the Eutectoid line

d) a=94% Fe3C=6%

Solid solutions have higher yield strength than corresponding pure metals because

dislocations are more difficult to move

The sample on the right failed from

ductile fracture under uniaxial tension

What are the safety concerns in the 361 lab? a) Burns from hot equipment or samples b) Damaged eyes from flying metal parts c) Crushed fingers from equipment with "pinch" or "crush" zones d) Cuts and abrasions from machining equipment e) All of the above

e) All of the above

What should not affect the actual hardness of an alloy steel? a) Fractional amount of proeutectic and eutectic phases b) Carbon level c) Pearlite colony size (width of finite Fe3C layers) d) Level of temper e) None of the above (all will influence hardness)

e) None of the above (all will influence harness)

Which of the following manufacturing processes are classified as material removal processes (two correct answers): (a) casting, (b) drawing, (c) extrusion, (d) forging, (e) grinding, (f) machining, (g) molding, (h) pressworking, and (i) spinning

e, f

Work hardening is the result of

increase in dislocation density upon deformation

The units for strain rate are

m/m/s

The fatigue strength can be increased by

reducing stress concentration in structure design

The fracture surface morphology on the right represents

transgranular fracture