IMSE251 Final Exam Study Cards

(21) Please examine the two steel grain microstructures after rolling processes (the lines in these microscopic images are grain boundaries). __________ shows a hot-rolled steel grain microstructure; whereas, __________ shows a cold-rolled steel grain microstructure.

(A) A is hot-rolled steel and B is cold-rolled steel

(3) What is the name of the copper-zinc alloy?

(A) Brass

(36) Which type of fit is designed for the mating hole and the shaft in the figure in Question 35?

(A) Clearance

(4) Which one of the following materials has the lowest carbon content?

(A) Cold finish ASTM 1040 carbon steel

(14) Which material is most likely to be an engineering ceramic material such as silicon nitride, silicon carbide, and a large number of oxides (instead of other types of engineering materials)?"

(A) Material A

(16) Which material is the stiffest (see diagram in Question 14)?

(A) Material A

(42) Which one of the two materials has better forgeability (easier to be forged)?

(A) Pearlitic steel

(31) Suppose surface A has roughness Rmax = 1 um and surface B has roughness Ra = 1 um. Which surface is smoother?

(A) Surface A

(38) Please judge the following statement: materials can be used for pattern making include wood, metal, and strong plastics.

(A) True

(45) Please judge the following statement: strain hardening happens during both cold and hot metal working (forming) processes, but the side effects of strain hardening can be eliminated in hot metal working because of the recrystallization temperature.

(A) True

(23) Continue with Gateway Arch" in Question 22. Use aluminum alloy instead of stainless steel."

(A) Would help

(33) Inspections can be done in two ways: by attributes or by variables. An inspection by using a go/no-go gauge is done by ________________.

(A) attributes

(48) In sheet metal bending, the metal is deformed ____________________ .

(A) beyond its yield strength but below its tensile strength

(1) Cr, W, and V are commonly used metal elements added to steels to produce cutting tools. They all have a _________ crystalline structure.

(A) body-centered cubic

(47) By looking into the metal grain structure on the sectioned crankshaft, this part is most likely produced by ________.

(A) forging (deformation)

(9) The tensile strength of the copper tube at the bent location will be __________."

(A) increased

(5) Please judge the following statement: units that we usually use to define stress are N and kN (newtons).

(B ) False

(20) __________ do not exhibit a yield point (the plateau yielding phenomenon on the stress strain curve), so an offset yield point (commonly set at 0.2% strain) is used on these materials.

(B) Aluminum alloys

(24) Which one of the following Fe-C phases does NOT have a body-centered cubic crystal structure?

(B) Austenite

(27) A steel bar (carbon content is known) is heated above the Austenite temperature and kept at that temperature for a long time (fully Austenitized). It then is cooled down to the ambient temperature at a constant given cooling rate (temperature decreases over time throughout the cooling curve). Which diagram would you use to find out the crystallization structure of this steel at the ambient temperature?

(B) Continuous-Cooling-Transformation (CCT) diagram

(2) Please judge the following statement: units that we usually use to define strain are mm and inch.

(B) False

(28) What is the eutectoid crystallization structure generated by following the isothermal cooling curve (dash line) shown in the figure?

(B) Fully Pearlite

(43) __________ eliminates the most of effects of the strain hardening, which would reduce the difficulty of performing secondary machining operations on the forged workpiece.

(B) Hot forging

(17) Two samples (that generate curves A and C in diagram in Question 14) after the above tensile tests are shown as below. Please judge which one is more likely the sample characterized by the above stress-strain curve C?

(B) Sample B

(29) Look at the three microscopic steel crystalline structures down below, which one most likely is a Bainite structure?

(B) Structure (B)

(22) Heat treatment of the stainless steel." (Swing of the Gateway Arch)

(B) Would NOT help

(11) Continue with the copper tube bending" question described in Questions 9. The ductility of the copper tube at the bent location will be __________."

(B) decreased

(18) Generally speaking, for a steel, as its tensile strength decreases, its hardness __________.

(B) decreases

(44) Open-die forging produces __________ metal grain microstructure with __________ metal grain size compared to sand casting of the same steel.

(B) directional, finer

(34) Shafts and wheels on a locomotive have to transmit high torque, so they have to be in a ________ fit.

(B) interference

(19) Young’s modulus is one of the ___________ of an engineering material.

(B) mechanical properties

(25) A six sigma process is one in which 99.99966% of all opportunities to produce some features of a part are statistically expected to be free of defects (3.4 defective features per million opportunities). Sigma (σ) refers to the statistical concept of __________.

(B) standard deviation

(8) The ductility of a steel test specimen can be found out by studying ___________________.

(B) the ability of the specimen to stretch before it fractures

(26) Annealing in a furnace gives ___________________ steel than normalizing in still air.

(B) weaker and more ductile

(35) Please refer to the figure on the right (unit: inch); what is the allowance is this shaft-hole fit design?

(C) 0.003

(12) Please identify what type(s) of deformation happened during this copper tube bending" process described in Questions 9."

(C) Both (A) and (B) happened

(32) Suppose surface A has roughness Rmax = 1 um and surface B has roughness Ra = 0.5 um. Which surface is smoother?

(C) Cannot tell

(7) Among the following five groups of manufacturing processes, which one exploits the ductility of certain metallic materials to produce parts?

(C) Deformation.

(50) This table presents a comparison of surface roughness produced by a few common production processes. The highlighted block indicates the usual surface roughness prepared by this process is within the two numbers at the two ends. Two of them are in blanks (I and II). Use your knowledge to choose a combination that goes into the two blanks (I and II).

(C) I-Hot rolling; II-Cold rolling

(49) Which of the following order represents the correct hardness order (from hardest to softest) of the structures of the same Fe-C alloy?

(C) Martensite > Bainite > Pearlite.

(15) Which material is the most ductile (see diagram in Question 14)?

(C) Material C

(30) What is the steel microstructure by following the continuous cooling Curve B on the CCT diagram:

(C) Pearlite + Martensite

(40) Which one of the following is NOT associated with casting?

(C) Strain-hardening

(13) The copper tube/tubing as shown in Question 9 is used for air conditioning and refrigeration and manufactured by (wire) drawing, which belongs to ______ material processing.

(C) deformation

(41) In hot-working, the workpiece needs to be heated to above __________________.

(C) recrystallization temperature

(10) Continue with the copper tube bending" question described in Questions 9. The Young’s modulus of the copper tube at the bent location will be ___________."

(C) the same

(6) Stainless steel’s resistance to corrosion and staining and low maintenance make it an ideal material for many applications. Besides carbon and iron, stainless steel must also have __________ (element).

(D) Chromium

(39) Which one of the following statements regarding die casting is FALSE?

(D) Die casting can cast metal with low fluidity by forcing molten metal under high pressure into a mold cavity.

(46) The angle or radius that allows the pattern to be removed from the sand when casting is called _________.

(D) draft

(37) In sand casting, a ________ is an extra void created in the mold that will also fill with molten metal. It provides a reservoir of material that can flow into the mold cavity to compensate for any shrinkage that occurs during solidification.

(D) riser

If we let the young’s modulus of AISI 4140 steel be 1, which value will most likely be the young’s modulus of plastics?

0.1.

The carbon contain in T10 tool steel is about ____.

1%

Please write down the steel microstructure by following the cooling curve:

50% Bainite +50% Martensite

In which one of the two steel microstructure, carbon has a higher solubility?

A

Which material has a lower toughness?

A

Which material is less ductile?

A

In the Iron-Carbon Equilibrium Diagram, which one of the following phases exists at a high temperature (> 912°C) environment?

Austenite.

Which material has a lower elastic modulus?

B

Which material has a lower yield strength?

B

Which material has a lower tensile strength?

B

Which material is more likely to be bronze while the other one being cast iron?

B

Which of the following will be the best material to make gage blocks to maintain their highaccuracy for everyday use in manufacturing plants?

Carbide steel.

On Boeing 787 airplanes, which type of material is used the most?

Composites.

What materials are used to mint the 25-cent coins now?

Cu + Ni

A steel bar (carbon content known) is heated to a certain temperature and kept at that temperature for a long time (say, five hours). Which diagram would you use to find out the crystallization structure of this steel at that temperature?

Equilibrium phase diagram.

According to the video “Eye safety,†when should you wear eye protection?

Every moment on the job in a machine shop.

Generally speaking, which structure has a better ductility (ability to deform with fracture)?

Face-centered cubic

Which heat treatment process will give the maximum ductility to a machined metal part?

Full annealing.

Please write down the steel microstructure by following the cooling curve:

Fully Bainite

Please write down the steel microstructure by following the cooling curve:

Fully Martensite

Which one of the following represents the most common heat treatment processes?

Hardening.

Which of the following order represents the hardness order (from hardest to softest) of the structures?

Martensite > Bainite > Pearlite.

Can the young’s modulus of a material be greatly changed by manufacturing processes?

No.

Which one of the following heat treatment methods CANNOT improve the treated metal’s machinability?

Quenching.

____________ is the degree of consistency achieved with a measurement device when thesame person uses it to measure a same dimension several times.

Repeatability.

Which one of the following is NOT among the purposes of heat treatment?

To alter the shape of a part.

Both brass and bronze contain copper.

True.

Both steel and cast iron are iron-carbon alloys.

True.

Which one of the following quenching media quenches fastest?

Water

According to the video “Eye safety,†do you need to wear eye protection when you just visit a machine shop?

Yes.

Can the ductility of a material be greatly changed by manufacturing processes?

Yes.

Can the yield strength of a material be greatly changed by manufacturing processes?

Yes.

Why did you feel hard to bend the copper tubing (or other specimen) back to shape?

Yield strength increased by strain hardening

In full annealing, the workpiece needs to be heated to _______________.

above the lower transformation temperature (A1)

To study the effects of cooling rate on steel crystallization structure, it is needed to heat the steel into _____________ first.

austenite

In tempering, the workpiece needs to be heated to _______________.

below the lower transformation temperature (A1)

Atoms in most metals have a ____ structure.

crystalline

Generally speaking, as tensile strength increases, material’s ductility _________________

decreases.

Tolerance is usually ___________________.

defined by product designers.

Generally speaking, when heat treatment of steel parts, the faster the cooling rate, the ____________ the parts will be after the heat treatment.

harder

Generally speaking, metals have _____________ thermal conductivity than plastics.

higher

Measuring and gauging is used__________________

in all phases of manufacturing.

Typically, the brittleness of the steel _____________ when tempering temperature decreases.

increases

Generally speaking, as tensile strength increases, material’s hardness _________________

increases.

Shafts and wheels on a locomotive have to transmit high torque, so they have to be in a__________ fit.

interference

Density is one of material's ___________

physical properties.

Normalizing gives ___________________ steel than full annealing.

stronger and more brittle

Normal distribution can be presented as a bell-shaped curve. The center location of the curveis determined by _______________.

the mean.

The inspection can be done in two ways: by attributes or by variables. Surface roughness measurement is done by ________________.

variables.