Materials Lab Quiz

Question 1

What does DTBT stand for?

Answer 1

Ductile to Brittle Transition Temperature

Question 2

What does the Charpy test achieve?

Answer 2

Characterizes the toughness of a material

Question 3

What does the final swing height of the Charpy test tell us

Answer 3

The impact energy it took to break the material

Question 4

What type of crystal structure is used in the Charpy test? Why?

Answer 4

BCC because they show a ductile to brittle transformation with temperature change

Question 5

When a sample fractures, how can you tell using your eyes if it is shear or brittleness?

Answer 5

Shear has a smooth surface. Brittleness has fine-grained and cleavage surface

Question 6

What is the force of the pendulum in the Charpy test

Answer 6

60lbf

Question 7

What is the procedure of the Charpy lab

Answer 7

1. Review safety considerations.
2. Label each specimen using a hammer and punch
3. Measure the initial lateral dimensions of all specimens.
4. Conduct impact tests on 5 1018-steel specimen
5. Measure lateral dimensions after impact.

Question 8

What equation is this for?
𝒎𝒈𝒉𝟏 − 𝒎𝒈𝒉𝟐 = 𝒎𝒈(𝒉𝟏 − 𝒉𝟐)

Answer 8

Impact Energy Equation

Question 9

Charpy Lab 1 Methodology

Answer 9

1. Establish Hypothesis
2. Prepare the samples
3. Create a notch on the sample
4. Have the samples in different temperatures for at least 15 minutes (boil water, room
   temperature, ice water, and liquid nitrogen)
5. Remove the samples from their environment and start testing by placing them on the impact machines.
6. Set up the machine correctly following the operating procedure.
7. Collect data, process data, and create a discussion and conclusion.

Question 10

What standard establishes preparing and notching samples for a Charpy experiment

Answer 10

ASTM standard E23

Question 11

Charpy Impact Test Operating Procedure

Answer 11

1. Measure and Cut the Notch
2. Measure and record the dimensions of the specimen.
3. Adjust the height of the impact machine to 22~24 in.
4. Lift the striker and lock.
5. Zero the friction pointer.
6. Place the specimen in the correct Charpy impact position (use tongs if needed).
7. Hit the lock lever to release the striker.
8. Read and record the data (Energy and temperature).

Question 12

What structure has an atom at the center of all 6 faces and at every corner?

Answer 12

FCC

Question 13

What structure has an atom at every corner and in the center

Answer 13

BCC

Question 14

What line shapes does FCC and BCC make on an Impact Energy/Temperature

Answer 14

FCC is flat across all temperatures. BCC is a sideways lightning bolt

Question 15

What is the definition of Hardness?

Answer 15

Measure of materials resistance to plastic deformation

Question 16

What is the Rockwell Hardness testing Scale A Indentor and Major Load?

Answer 16

Diamond, 60 kg

Question 17

What is the Rockwell Hardness testing Scale B Indentor and Major Load?

Answer 17

1/16in ball, 100kg

Question 18

What is the Rockwell Hardness testing Scale C Indentor and Major Load?

Answer 18

Diamond, 150kg

Question 19

What is the standard for Rockwell Hardness Testing of Metallic Materials?

Answer 19

ATSM Standard E-18

Question 20

What is the methodology for the Rockwall Hardness Test?

Answer 20

1. Make sure that the station, and sample is clean before testing.
2. Select proper indenter, tip and proper load according to the scale of testing.
3. Calibrate the machine by using the test blocker.
4. Read the operating instructor in laboratory handout to operate the machine correctly.
5. Test on 2 test blocks and 5 given specimens and record the data in tabular format
6. Apply given formula(s) to find average and standard deviation value at each specimen.
7. Apply given formula to investigate the correlation between Hardness value and Tensile strength.
8. Discussion and Conclusion.

Question 21

What is the operating procedure for the Rockwell Hardness Lab?

Answer 21

1. Select the correct tip (A, B or C).
2. Place the proper anvil on elevating screw.
3. Place the specimen on top of the anvil.
4. Make sure the load handle is in the unloading position (direction toward you).
5. Make sure the weight is correct (A, B or C).
6. Raise the specimen into contact with the Indenter by turning capstan hand wheel clockwise. Continue motion until feeling the tip
   touch the sample. Align the 0 point on the clock with the large indicator.
7. Start spinning motion so that the small indicator turns from black dot to red dot (about 2.5-3 revolutions on the large indicator.
8. Adjust the 0 point on the clock again so it could align correctly with the new position of the large indicator.
9. Turn the load handle away from you to activate loading mode. Wait for about 60-80 seconds so that the load can be applied. The large indicator needs to be completely stopped before moving on to the next step.
10. Turn the load handle back to it original position (unloading mode) and read the result from the large indicator. (A and C are on the
    black scale; B is on the red).
11. Turn the capstan hand wheel counterclockwise to lower the elevating screw and specimen so they clear the indenter. Remove the
    specimen or repeat the test.

Question 22

Brinell Hardness to tensile strength

Answer 22

𝑻𝑺 𝑴𝑷𝒂 = 𝟑. 𝟒𝟓 × 𝑯𝑩
𝑻𝑺 𝒑𝒔𝒊 = 𝟓𝟎𝟎 × 𝑯𝑩

Question 23

Fine grains lead to:

Answer 23

-More grain boundaries
-More obstacles to dislocations
-Higher strength required for plastic deformation

Question 24

This phase is formed when carbon steel is heated for more than 30 hours at temperatures exceeding
690°C

Answer 24

Spheroidite

Question 25

in iron-carbon alloy, this phase contain 100% Iron, contains iron in the alpha- or delta-iron form.

Answer 25

Ferrite

Question 26

This phase exists only above 723°C and below 1500°C.

Answer 26

Austenite

Question 27

This phase forms during slow cooling of iron-carbon alloys (usually from 723°C to room temp).

Answer 27

Pearlite

Question 28

This phase forms during quick cooling rate of iron-carbon alloys (usually in the range of 10−1 𝑡𝑜 10 𝑠𝑒𝑐𝑜𝑛𝑑𝑠.)

Answer 28

Martensite

Question 29

This phase is formed at cooling rates slower than that for martensite formation and faster than that for ferrite and pearlite formation.

Answer 29

Bainite

Question 30

generally forms at temperatures between 550 and 400°C

Answer 30

Upper bainite

Question 31

generally forms at temperatures between 400 and 250°C

Answer 31

Lower bainite

Question 32

What is the Lab 3 Methodology

Answer 32

1/ Prepare sample: ➢Regular sample ➢Mounted sample (follow instructor guide) 2/ Grinding Procedure: ➢Using Emery papers with the following grit size: 120 -> 240 -> 320 -> 400 -> 600 ➢Turning 90 degree before moving on to the next grit size. 3/ Polishing Procedure: ➢Use suspension liquid of Aluminum Oxide with the following order: 5μm -> 1 μm -> 0.05 μm 4/ Etching Procedure: ➢Using 3% Nital Liquid carefully applying on the polished surface, then wash it with water after a few minutes. 5/ Observing Grain size by using Microscope: ➢Place the specimen under the microscope to observe the grain size.

Question 33

What is the Lab 3 Operating Procedure

Answer 33

1. Open water line located behind grinder(s). 2. Starting on the 120 and then 240 grit size, place prepared specimen, or metal face down of abrasive surface, and being sliding specimen against abrasive in a forward and backward motion. 3. Next, turn specimen 90 degrees and repeat above procedure on the 320 Grit surface. 4. Again, turn specimen 90 degrees and repeat procedure (2) now on the 400 Grit surface. 5. Finally, turning specimen 90 degrees and repeat procedure (2) now on the 600 Grit surface. 6. Close water line.

Question 34

What does this equation equal? 2^𝑛−1

Answer 34

N is average number of grains per sq. inch at 100X

Question 35

What does this equation equal? 0.254/(2^(𝑛−1))^(1/2)

Answer 35

Grain diameter

Question 36

What is the Lab 4 tensile testing methodology?

Answer 36

1. Preparing the specimens 2. Measuring dimensions 3. Turning on the computer and software. 4. Turning on the machine and ensure the machine and the software are in sync. 5. Securely attaching the specimen to the machine Grippers 6. Setting up the test/test method in the software. 7. Running the test 8. Collecting result

Question 37

What is the operating procedure for the tensile tester?

Answer 37

1. Installing the specimen to the lower gripper 2. Installing the specimen to the upper gripper 3. Installing the extensometer to the middle of the gauge length

Question 38

What is the operating pressure for the tensile tester software?

Answer 38

1. Follow the instructor to install the specimen correctly to the machine 2. Open the Software, and select Test. 3. Select Existed Test or go To Browser and select C:\ >> select User >> Public >>Public document >> BlueHill 3 >> Bluehill >>Tension Example >> Open 4. Select Method to define this test. 5. In General section, select method, select Metric Unit. 6. In the Specimen section, select rectangular shape, also you can inside specimen dimension in this section. 7. In Test Control Section: ➢ Start test >> “By the start button” ➢ Strain >> “Extension” or “ Extensometer” ➢ Test >> Ramp 1 >> Choose Extension control >> Rate 10 mm/min if soft material, 2.45-3.56 mm/min if stiff material ➢ End of Test >> Rate of Load >> 40% or Extension control at 50 mm, etc. (You can set up many conditions to stop) ➢ Data >> Criteria 1 >> Interval 1 >> 100 ms (or set up any data interval you want) 8. In Console Section: (Set up monitors and keys for monitoring the test) ➢ Live displays Selected live displays >> need to have : Extension, Load, Tensile Strain, Tensile Stress. ➢ Soft key >> choose Balance Load and Zero Extension (optional) 9. In Workspace Section: Operate Inputs >> Setup >> select Specimen lable, Rate 1, Comment, Length, Thickness, Width, etc. ▪10. In Prompted Test Prompt Sequence >> choose Prompt Before Test and Show workspace after calculations # Sample: 1 or 5 or any integer number depend on users. 11. Follow some other extra set up of the instructor and start the test. ▪12. Start the test