Sheridan College Institute of Technology

and Advanced Learning

Materials Engineering Laboratory Book

School Of Mechanical and Electrical Engineering and

Technology

Copyright © 2013, Sheridan College / Faculty of Applied Science and Technology / Mechanical and Electrical Engineering Department Prepared by: Safaa Saleh, PhD

Professor & Coordinator of Mechanical and Electrical Engineering labs Sheridan College Faculty of Applied Science and Technology School of Mechanical and Electrical engineering & Technology

Reviewed by: Marisela Strocchia, PhD.

Professor and Coordinator Manufacturing Management Program Technology Fundamentals Program Sheridan College Faculty of Applied Science and Technology School of Mechanical and Electrical engineering & Technology

Supervisor: Farzad Rayegani, PhD & P. Eng. Professor and Associate Dean of Mechanical and Electrical Engineering Sheridan College Faculty of Applied Science and Technology School of Mechanical and Electrical engineering & Technology

Updated April 2015 by Dr. Marisela Strocchia and Mr. Bruce Reesor.

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Index

Subject Page 1. Introduction………………………………………………………………..4 2. Laboratory Rules and Ethics…………………………………………….... 4 3. Some important definitions…………………………………………….…..5 4. Experiments………………………………………………………………..6

4.1 Experiment 1: Metal Identification……………………………….……6 4.2 Experiment 2: Investigation of Weld Samples ………………….……11 4.3 Experiment 3: Izod Impact (Toughness) Test of Metal Samples .......... 14 4.4 Experiment 4: Tensile Test of Plastic Samples ……………………… 16 4.5 Experiment 5: Cold Working and Annealing...…………………… .... 18 4.6. Experiment 6: Effect of Heat Treating on 1045 Steel….….………….20 4.7. Experiment 7: Microstructure and Hardness of Carburized Steel… ..... 23 4.8 Experiment 8: Ultrasound Non-destructive Testing………..…….……25

5. Appendix Introduction to WHIMS………………………………………….…….…..27

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Introduction to Materials Engineering lab Materials engineering is an applied science that interfaces with all technologies using materials (civil, mechanical, electric…). Materials engineering is producing a predetermined set of properties in materials based on its structure. Students in this course learn the basics to selecting the correct materials for the application in which the engineered part is being used. Specifically in the lab component of the course, students test a variety of mechanical, chemical and physical properties and analyze the uses of different materials. (Budinski, K. and Budinski, M., 2010)

1. Laboratory Rules and Ethics

In order to use the lab in an efficient and safe manner you have to:- 1. Come prepared with your lab book, lab report, and any calculating and drawing aid materials, a safety quiz will be administered in the first five minutes of the class. 2. Read all written instructions carefully, before you start an experiment. 3. Ask your teacher if not sure of any step. 4. Pay attention to your own safety and safety of others. 5. Avoid sudden or rapid motion in the laboratory especially near chemicals, laser or sharp instruments. 6. Stand while handling equipment and materials. 6. Never eat, drink or chew gum in the laboratory. 7. Keep your work area tidy and clean. Keep aisles clear. 8. Keep your clothing and hair out of the way. Remove any loose jewelry. 9. Protect your feet from any possible harm by heavy materials by wearing closed shoes "not sandals", in industrial environment it is mandatory to wear protective shoes. 10. Wear CSA approved safety goggles in the lab. 11. Use only the apparatus you should use for your experiment, don't try to operate any other apparatus without prior permission from your teacher and lab technicians. 12. Know the location of material safety data sheet (MSDS) information, exits, and all safety equipment such as the first aid kit, fire blanket, fire extinguisher and eye wash station. Know the location of emergency stop buttons on machines / equipment Before using machines or equipment make sure machine guards are in place as required 13. Alert the lab technicians immediately if you see a safety hazard, including unsafe acts (unsafe behavior), unsafe conditions i.e. as broken glass, a spills, trip/ slip hazards. 14. Clean up and put away, in a tidy manner, any equipment after you are finished. 15. Wash your hands after the end of each experiment.

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3. Some Important Definitions

According to Budinski, K. and Budinski, M. (2010); Callister, W. and Rethwisch, D. (2010); and Neely, J., materials engineering is producing a predetermined set of properties in materials based on the structure of materials and/or inventing new materials and devices. The structure of materials relate to the arrangement of its internal components. On subatomic level, structure involves electrons within individual atoms; on atomic level, structure encompasses the organization of atoms or molecules relative to one another; microscopic involves large groups of atoms agglomerated together; macroscopic may be viewed with naked eyes. Property is a material trait in terms of the kind and magnitude of response to specific stimulus. For example, a body under the effect of forces will experience deformation; a polished metal surface will reflect light. All materials follow the laws of chemistry and physics in their formation, reactions and combinations. Therefore, materials properties can be classified as chemical, physical, and mechanical properties. Material selection; when selecting materials for a specific engineered part, physical, chemical and mechanical properties are very important factors in materials design and selection. Also, materials should be capable of being processed and shaped and do not harm the environment; therefore in selecting materials there is a trade-off between the use of the material and the economics of it. Load is the amount of force applied to the specimen. Normal stress (σ) is force per unit area from the initial specimen dimensions. σ = F/A The change in length is called deformation Strain (€) is the ratio of the deformation divided by the initial specimen length. The elastic limit of a material is the linear relationship between stress and strain in the elastic region (it is a measure of stiffness). The slope of the stress strain curve is the modulus of elasticity E; E=stress/strain = σ/€ Yield strength or yield point of a material is defined as the stress at which a material begins to deform plastically. Ultimate tensile strength is the maximum stress observed in a tensile test. Necking begin when this value is reached. Tensile Strength is a measure of the ability of a material to withstand a longitudinal stress, expressed as the greatest stress that the material can stand without breaking. Break Point; when the specimen finally breaks and the load returns to zero. Sometimes this is the maximum stroke or extension point. Toughness: is the ability of a material to absorb energy and plastically deform without fracturing It is the amount of energy per unit volume that a material can absorb before breaking

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Purpose:

4.EXPERIMENTS 4.1 Experiment NO. 1: Metal Identification

STEEL 1018, STAINLESS STEEL 4130, “DELRIN” ACETOL, STAINLESS STEEL 304

To identify samples of different metals using various methods of identification.

Theory:

Different chemical, mechanical and physical properties allow identifying materials. Students are expected to use the following properties to identify different metals:

1. Hardness is a mechanical property defined as the resistance of a material to deformation, indentation, or penetration by means such as abrasion, drilling, impact, scratching, and/or wear (Budinski, K. and Budinski, M., 2010).

2. Density (D) is a physical property of all three states of matter. It is defined as the mass of a given volume of a material or mass (m) per unit of volume (v)

Procedure:

Identify various materials by their properties of:

a) Color, b) Ferromagnetism, c) Density and, d) Hardness.

List your findings in Table 1 according to color and ferromagnetism .

D = m/V 3. Ferromagnetism is a physical property.

Most ferrous metals are attracted to a magnet.

4. Relative hardness: To check metals for relative hardness; scratch one sample with another and the softer sample will be marked

5. Appearance/Color

Materials: 9 different samples numbered: 2, 3, 4, 5, 6, 7, 24, and 28. Your sample box also includes a magnet. The material(s) are: BRASS UHMW (ULTRA HIGH MOLECULAR WEIGHT PLASTIC), TITANIUM, ALUMINUM, COPPER,

Table 1: Identification of materials by color and ferromagnetism

Sample number

Color Ferrom

agnetis

Density

(Kg/m3)

2

3

4

5

6

7

8

24

28

6

Density test procedure: Source: PASCO – Archimedes principle equipment

1. Using a balance, find the mass of each of the samples.

2. Using the calipers, measure the dimensions of the samples and calculate the volume of these objects (Figure 1).

Figure 1: Mass and dimension measurements

3. There is no simple formula for the volume of the irregularly shaped objects so it is necessary to find the volume by measuring the volume of water they displaces;

A. Put the beaker under the overflow can spout as shown in Figure 2.

Figure 2: Overflow Can

B. Pour water into the overflow can until it overflows into the beaker. Allow the water to stop overflowing

on its own and empty the beaker into the sink and return it to its position under the overflow can spout without jarring the overflow can.

C. Tie a string on the irregular object. D. Gently lower the irregular object into

the overflow can until it is completely submerged. Allow the water to stop overflowing and then pour the water from the beaker into the graduated cylinder. Measure the volume of water that was displaced by reading the water level in the graduated cylinder in milliliters (1 ml = 1 cm3).

4. List the objects in order from least to greatest volume. Is this the same order as the mass list? Are any of the volumes nearly the same?

5. Calculate the density of each object. List the samples in order from least to greatest density. Is this list in the same order as either the mass list or the volume list? Do any of the samples have densities that are nearly the same?

Sample number

Mass

(Kg)

Volume

(m3)

Density

(Kg/m3)

Table 2: Density

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Table 2: calculation of the density of metals.

Rockwell Hardness Tester:

Operating Instructions:

1. Before beginning the test, make sure that you are using the correct machine. There are two Rockwell machines in this lab, one of which is set up for Rockwell "B" and the other for Rockwell “C”. They are clearly labelled on the front of the machine. Also read the precautions at the end of these instructions.

2. For hardness testing, ALWAYS use the Rockwell “C” scale to start; if the material is too soft, for example less than RC 20, re- test for the Rockwell “B” scale

3. Before starting the test, ensure that the handle 1, located as shown for the Rockwell C machine but near the bottom for the Rockwell B machine, is pulled forward (counter clockwise) as far as it will go.

4. Ensure that the correct anvil is on the elevating screw, i.e. the flat anvil for flat specimens etc.

5. Raise the specimen to contact the penetrator by turning the capstan hand pointer is on the dot. Continue further until the large pointer is approximately vertical.

6. Turn the bezel of the dial gauge until the "SET" line is directly behind the large pointer. To do this;

a) Use the large ribbed ring just below the capstan hand wheel; for the "B" machine. b) For the "C" machine, a small downward pointing lever is attached directly to the bezel through the opening in the cowl below the dial gauge.

7. Release the weight (MAJOR LOAD), to do this; for the “B” machine, depress the flat lever surrounding the ribbed adjusting ring. For the”C” machine; trip the crank handle 1 rearward. It is important not to force the c r a n k handle but to allow t h e dashpot that is built into the m a c h i n e t o c o n t r o l the load application.

8. When the l a r g e p o i n t e r c o m e s t o rest, return the crank handle to the starting position. This removes the MAJOR LOAD. The minor load is still applied.

9. Read the scale letter (B or C) and the corresponding Rockwell hardness number from the dial gauge.

10. Remove the MINOR LOAD by turning the capstan hand wheel 4 counter clockwise t o lo wer t h e e l e v a t i n g screw and specimen so that they clear t h e penetrator.

11. Remove the specimen or repeat the test.

12. Record the hardness for the 12 samples in table 3 and compare your readings to the ASTM values.

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Sample Number Recorded Hardness

2

3

4

5

6

7

8

24

28

Table 3: Hardness values

PRECAUTIONS FOR THE ROCKWELL TEST:

PENETRATOR: Be sure t h e m a t i n g surfaces of the penetrator a n d t h e plunger rod are clean and free of dirt, chips and oil; these p r e v e n t p roper seating and cause a false "ROCKWELL" hardness test. After changing any penetrator or putting a new ball in a ball chuck, or changing the anvil, several tests should be made to seat these parts before any hardness readings are taken. ANVILS: Be sure the mating faces of the anvil and the end of the elevating screw are clean and free of dirt, chips and oil. These prevent good seating and cause a false "ROCKWELL" hardness test. If the shape o f the part i s so irregular that i t

cannot be solidly supported on any of the standard anvils without shifting under application of the MAJOR LOAD, then a special anvil or method of support must be devised. SPECIMEN: Be very careful of the placement of the test specimen on the anvil so it is solidly supported. Any loose scale, coarse tool marks, nicks or burrs which might make contact with the anvil will cause a false test by collapsing under the MAJOR LOAD and t h u s a l l o w the work to move. Loose or flaking scale where the penetrator makes contact with the specimen may chip away and cause a false test. This must be filed or ground away. Decarburized surface metal must be filed away to permit the penetrator to start the test in the good metal underneath.

Fig. 3: Rockwell Hardness tester (source; Neely &

Bertone, Practical Metallurgy and Materials of industry - sixth edition)

1. Crank Handle 6. Small Pointer 2. Penetrator 7. Large Pointer 3. Anvil 8. Lever for setting the Bezel 4. Weights 5. Capstan Hand wheel

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Discussion and Conclusion: • In the table below; identify the material samples by number. Your conclusions must

include the reason(s) for your identification, (hint; compare your findings of density and hardness to the international ones: ASTM tables).

• State sources of errors and your recommendations for improving them. • Why density and hardness are considered important tests for identifying materials. • What other tests would you suggest to use to identify materials

Sample No Identification Reasons for this Identification

2

3

4

5

6

7

8

24

28

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4.2 Experiment NO. 2: Investigation of Weld Samples

Purpose: To identify the effect of welding in two weld samples using hardness and microstructure analysis.

Theory: Welding is the process to join materials by application of heat (from gas, arc, induction, soldering). Parts are heated until they melt and flow together. Filler metals may also be used. Welding also happens by pressure, the joining is done without filler material (welding rod) or using a laser beam. After solidification, there is a region (Figure 1) that may have experienced microstructural and property alteration in the heat affected zone (HAZ).

Fig 1: Zones found in welding

Source: Budinski, K. and Budinski, M., 2010

According to Budinski, K. and Budinski, M. (2010); Callister, W. and Rethwisch, D. (2010); possible alterations include: 1. If the material was previously cold

worked, the HAZ may have experienced recrystallization and grain growth, and thus a diminishing of strength, hardness and toughness.

2. After cooling, residual stresses may form in the HAZ which weaken the joint.

As metals are welded the effects can be similar to heat treatment in the heat affected

zone. Consequently, when welding high carbon steel, it’s required to post-heat (annealing) or pre-heat prior to welding, otherwise the material becomes hard and brittle in the heat-affected zone.

Fig 2: Zones and boundaries in heat affected zone

Source: Globalspec.com

The following figures show the consequence of welding procedure.

Fig. 3: The coarsened grains in the base metal in the heat-

affected zone are caused by high-temperature grain growth.

Fig. 4: Cross section through weld in carbon steel showing

variation in hardness with and without pre- heat

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Materials: One sample is low carbon steel welded to low carbon steel. The second sample is high carbon steel welded to low carbon steel.

Apparatus:

1. Sample preparation equipment. 2. Rockwell Hardness tester. 3. Microscope with video camera

attached. Precautions:

• Protect your eyes wearing lab goggles.

• Keep your clothing and hair out of the way. Remove any loose jewelry

• When dealing with the Nital in the etching step, protect your hands wearing gloves and using a tong

• You have to control the time of etching to avoid dark spots and undesired coloration.

Procedure:

1. Grind the two samples o n s e v e r a l grades of abrasive paper.

• Turn the water flow and start with the coarse grit paper, move the sample back and forth with mild pressure until the scratches go in one direction (Figure 5).

• Move the sample on the less coarse paper, provided that the new scratches are 90˚ to the previous one.

Continue the same procedure for all the four grit papers.

Fig. 5: The Handimet roll grinder (photograph courtesy Buehler Ltd., Evanston, IL) (source; Practical Metallurgy and Materials Industry, 6th. Ed. text handbook)

2. Polish the two samples on the

rotating polishing wheel (Figure 6).

• Add few drops of aluminum oxide on the rotating wheel. Face the sample down on the wheel and slowly move around in the opposite direction to the rotation.

• When the sample is mirror bright and shows no scratches or lines. Clean it with water and wipe it with cotton immersed in methyl alcohol.

• Dry the sample with the help of hair dryer.

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Fig. 6: Polishing a sample on the rotating wheel (source; Practical Metallurgy and Materials Industry, 6th. Ed. text handbook)

3. Etch the sample with 2% Nital for 45

seconds in a petri dish (Figure 7).

Fig. 7: Etching a sample with Nital (source; Practical Metallurgy and Materials Industry, 6th. Ed. text handbook)

4. Stop etching by putting the sample

under a steam of water, then wipe it with cotton immersed in methyl alcohol and dry it with the hair dryer.

5. Take your sample to the microscope, The PAX software will be displayed in the computer.

6. Place your sample in the microscope. Use the 10X objective

7. Use the coarse focus adjustment and then the fine focus adjustment until you see a clear image in the computer screen. Change to the 20X objective to observe more details in the microstructure.

8. Observe the microstructure going slowly from one edge of the sample to the other.

9. Identify the various zones shown in figure #2. Take around 5 pictures to capture the HAZ zone and areas before and after the HAZ:

Click “capture” in the “PAXcam 3” screen

Save your pictures in the desktop folder

Save also the pictures in your memory stick

10. Perform hardness test across both samples. PLEASE FOLLOW THE ROCKWELL HARDNESS TESTER OPERATING INSTRUCTIONS AND PRECAUTIONS DESCRIBED IN PAGES 8 AND 9 OF THIS HANDBOOK. Record the values identifying each sample.

Observations:

Identify any areas which are significantly harder than the remainder of the sample. If possible, label the various weld area zones and microstructure on the microscope photographs.

Analysis: You are looking for various zones as per figures 2 & 3. Note the different grain sizes

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and compare with figure 1. In the low to low carbon steel, the hardness across the weld should be fairly constant. The high to low carbon steel sample will likely have a point of high hardness (figure 4) which could have been avoided by post-heating. Post-heating will temper or anneal the steel and eliminate the martensite which was caused by the quenching action of the base metal. For a service application, post-heating of this weld would be critical to prevent a failure.

Discussion and Conclusion:

1. Graph your hardness readings for both samples. Comment on the effect of welding on hardness

2. Comment on the effect of welding on the microstructure of steel.

3. Correlate betweenthe microstructure findings and your hardness readings.

4. Include the weld zone photos in your report.

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4.3 Experiment NO. 3: Izod Impact (Toughness) Test of Metal Samples

Purpose: Determine material toughness of three different materials and compare their behavior..

Theory: Izod impact is defined as the kinetic energy

needed to initiate fracture and continue the fracture until the specimen is broken. Izod specimens are notched to prevent deformation of the specimen upon impact. This test can be used as a quick and easy quality control check to determine if a material meets specific impact properties or to compare materials for general toughness. In a typical Pendulum Machine, the mass of the hammer (striking edge) mass (m) is raised to a height (a); this is the vertical height from the raised mass to the impact point. Before the mass (m) is released, the potential energy will be:

Ep = m g a After being released, the potential energy will decrease and the kinetic energy will increase. At the time of impact, the kinetic energy of the pendulum:

Ek = 1/2 m v2

All potential energy was

transformed in kinetic : Ek = Ep

m g a = 1/2 m v2

v2 = 2 g a Ѵv2= Ѵ2 g b

a = R (1 – cos α) b = R (1 - cos β)

Initial energy = = Ei = mga = mg R (1 - cos α)

Ei = W R (1 – cos α)

Energy after the rupture = = Er = mgb = mgR (1 - cos β) Er = W R (1 - cosβ)

Energy absorbed by the specimen Ei - Er = E abs = W R (1 – cosα) - W R (1 - cosβ) E abs =W R (cos β - cos c) or E abs = m g (a - b) = W(a – b) ISO and ASTM standards express impact strengths in different units.

The impact velocity will be: v = Ѵ2 g b = (2 g b)1/2

ISO impact strength is expressed in kJ/m2 or ft- lb/ft2. Impact strength is calculated by dividing

Fig 1: Schematic diagram of a pendulum

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The energy absorbed by the specimen in J by the cross sectional area at the notch. ASTM impact strength is expressed in J/m or ft- lb/ft. Impact strength is calculated by dividing impact energy in J (or ft-lb) by the thickness of the specimen. The higher the resulting number; the tougher the material. Materials:

Fig 2: Dimensions of the tested material

Apparatuses:

Fig 3: Izod impact testing unit

Procedure:

1. The machine should be braked. Release the brake by moving the Operating Lever to Hole 1. Hold the Latch Prevent Bar in the up position by pressing down on the short end of the bar.

2. Insert the Stop Pin into Hole 1 to prevent accidental release of the pendulum.

3. Set the pointer at the maximum dial value of the range for the test (at 50 in the orange scale)

4. Pull the pendulum to the right side and install the metal safety block against the anvil to hold the pendulum out of the way. Let the edge of the pendulum rest against the block and check that both the block and pendulum are secure (See FIGURE 4).

5. Make sure the equipment is balanced with no error by operating it without a specimen:

- Raise the pendulum counter clockwise by hand to the low latch position and listen for a “click” to indicate that the pendulum is latched. Gently lower the pendulum against the latch.

- Be sure all personnel and objects are out of the pendulum swing area.

- Close the safety gate and move the Stop Pin from Hole 1 to Hole 2 to prevent brake application during the test.

- Release the pendulum by quickly moving the operating lever from the latched position (hole 1) to the Release position (hole 2).

- The pendulum will swing to the left and rotate the pusher arm to position the pointer on the dial to indicate the energy.

After the pendulum has swung through two full swings, brake the equipment by moving the operating

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- 2) to the b r a k e po s i t i o n - Once the pendulum has stopped

swinging, move the operating lever to the “latched” position and place the Stop Pin back in Hole 1. Read the pointer indication. If the equipment is balanced (no error) the pointer should be in the zero value of the range for the test. If you find an error, record it for your calculations.

6. Open the safety gate to start the experiment with samples. Pull the pendulum to the right side and install the metal safety block against the anvil to hold the pendulum out of the way. Let the edge of the pendulum rest against the block (See FIGURE 4), and check that both the block and pendulum are secure

Figure 4: Safe installation of the metal block

7. Clamp a specimen of a given material and dimension into the pendulum impact test fixture, provided that:

- The notched side facing the pendulum (with the shortest side in the upper position) (See FIGURE 5).

- With the help of a gauge; make sure that the centerline of the notch is in line with the top surface of the vice.

Figure 5: Proper installation of the sample

8. Set the pointer at the maximum dial value of the range for the test (at 50 in the orange scale)

9. Raise the pendulum counter clockwise by hand to the low latch position and listen for a “click” to indicate that the pendulum is latched. Gently lower the pendulum against the latch.

10. Be sure all personnel and objects are out of the pendulum swing area.

11. Close the safety gate and move the Stop Pin from Hole 1 to Hole 2 to prevent brake application during the test.

12. Release the pendulum by quickly moving the operating lever from the latched position (hole 1) to the Release position (hole 2).

13. After the pendulum has swung through two full swings, brake the equipment by moving the operating lever from the Release position (hole 2) to the brake position

14. Once the pendulum has stopped swinging, move the operating lever to the “latched” position and place the Stop Pin back in Hole 1. Read and record the pointer indication for the amount of energy used to break the sample (Eabs).

15. Open the safety gate, measure and record the Pendulum’s angle of rise.

16. O n ce f i n i s h e d, p i c k u p t he br o ke n p i e ce s , t he pe n d u l u m s h o u l d b e a t t h e bo t t o m o f t h e s w i ng , a p p l y t he b r a k e , a n d c l o s e t h e s a f e t y g a t e .

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17. Repeat the experiment with the remaining

samples 18. Brake the equipment by moving the operating

lever from the Release position (hole 2) to the b r a k e po s i t i o n

Given: m = 12.07 kg (0.826 slugs) a = 573mm (1.88 ft.) v = 3.35 m/s (11 ft/sec) R = 800mm (31.5in.) Angle of Fall = α = 73.5o

Record: Angle of Rise = β = ? Eabs = ? Calculations: 1. Potential Energy. 2. Impact Velocity. Verify with given value. 3. Initial Height of Pendulum (a). Verify with given value. 4. Pendulum arc height after impact (b). 5. Energy required breaking sample (Eabs) 6. Percentage of error for calculated values with respect to recorded values. (Give reasons for any error.) 7. ISO & ASTM impact strength for each sample

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4.4 Experiment NO. 4: Tensile Test of Plastic Samples Purpose:

To compare the tensile properties of Acrylic, Nylon, and Polycarbonate (Lexan) samples.

Theory: According to Budinski, K. and Budinski, M. (2010); elasticity is the property that measures the ability of a material deformed to return to its original size and shape when unloaded. On the other hand, the Property of material to be deformed repeatedly without rupture by the action of a force, and remain deformed after the force is removed is called plasticity. The elastic limit of a material (Fig. 1) is the point beyond which a deformed object cannot return to its original shape. The solid molecules have been pulled far enough apart that the molecular forces cannot return the solid to its original shape. It’s the linear relationship between stress and strain in elastic region (A measure of stiffness)

Fig. 1: stress strain curve of a material According to Hook’s law the slope of the stress strain curve is the modulus of elasticity E;

The tensile testing can be summarized as in figure 2.

Fig. 2: A summary of the tensile testing experiment It is important to highlight that the UTS tester indicates Force vs ∆L.

Remember to divide by the area in order to calculate stress. Materials: Acrylic, Nylon, and Polycarbonate (Lexan) samples.

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Apparatus: The UTS tester records real time load and extension values on small samples using a 20 kN load cell. The results are plotted on a graph as load vs. extension, with yield point; max load and breaking load recorded (Figure 1).

Procedure: 1. YOU MUST WEAR SAFETY GLASSES,

ALL THE TIME. 2. Turn on the controller, the united tensi le

machine (UTM), and the computer. 3. Measure Width and Thickness of each

sample and record data. 4. Run the Datum program (A picture of the

machine appears on the monitor, after the picture disappears from the screen, a small American flag appears in the right side of the computer; click on it, a pull up menu appears, click on DATUM, wait for the four screens to disappear; the force vs. extension graph will appear).

5. Push the start bottom on the UTS. 6. Click on the “new” icon in the top toolbar 7. Click on “template 111”, click “apply” 8. Click on “scales”, pick “PC” 9. Pick “POSITION”, then “LOADCELL”, finally

“extensometer position XHDmm” 10. Click “apply” and watch the lower right

side corner until the ”multicolor stripe”

disappear 11. Click on “sample information”. Indicate in

“Customer name” today’s date. Hit tab until the cursor moves to “spec ID” (nylon or acrylic or lexan); hit tab

12. Record the “Width”, hit tab 13. Record the “Thickness”, hit tab 14. The area of the sample is displayed, hit

“apply” 15. Click on the “operate” icon in the top

toolbar 16. Click on the “jog” icon in the top toolbar,

“ENABLED” appears in the “POSITION” 17. In order to load Sample: 18. The jog buttons on the machine are now

ready to operate. Jog machine up and down as needed to load the part properly. Make sure the part is straight and centered (see Figure 2).

FIGURE 2: Part loaded

19. “Zero” force by clicking on “force = 0”and “zero” extension by

clicking on “Pos” Hit “test” 20. Observe the behavior of the sample in

the machine and relate to the graph in the computer, after the sample breaks,

Fig. 1: The UTS tester

20

remove the sample from the jaws. Make a comment and hit enter, the distance between the jaws decreases KEEP YOUR HANDS CLEAR.

21. The “Test Report” screen displays, record the “test number”, pick the test number, and pick “Graph”.

22. The screen “Metric tensile properties of plastic“ appears, pick “report”, click “PDF” on the top tool bar

23. Save your file in the desktop lab folder. Hit “publish”

24. Close “print preview” on the top tool bat; close the “metric tensile” screen; hit “exit”

25. Go back to “sample info”, click “add to report”

26. Identify the next sample and repeat steps 12 to 25 until you have completed all your samples

27. Copy your data to a memory stick. 28. Exit the “Datum” program

Discussion and Conclusions: For each sample;

1. Compare the various sample tensile properties in terms of their elasticity, young’s modulus, yield, tensile strength, breaking load, and ductility.

2. Comment on the shape of the curves and the different properties of each material.

3. Calculate the percentage error for the experimental versus accepted values for Young’s Modulus (Hint: search for accepted values in peer review journals

4. Comment on how you would use each of the materials along with its limitations.

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Bibliography

• Budinski, K. and Budinski, M. (2010). Engineering Materials: Properties and selection, 9th ed. New Jersey: Prentice Hall

• Callister, W. and Rethwisch, D. (2010). Materials Science and Engineering: An introduction. 8th ed. Danvers, MA: John Wiley and sons

• Hosford, W. (2008). Materials for Engineers. Cambridge University Press: Cambridge: Cambridge University Press

• Lab Equipment’ handbooks (Rockwell, Izod, UTS)

• Neely, J. (1985). Practical Metallurgy and Materials of Industry. New Jersey: Prentice Hall

• National Science Foundation. (2015). Engineering challenges of the 21st century. Retrieved from internet on Jan 15, 2015, 1 pm

• Paul Degarmo, E. Black, J, and Kohser, R. (2003). Materials and Processes in Manufacturing. Danvers, MA: John Wiley and sons

• Strocchia, M. (2013-2015). Engineering materials class files

• WHMIS Hazard Symbols retrieved from internet on January 2014

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WHMIS I N T R O D U C T I O N

APPENDIX hazards and training in safe work

The Workplace Hazardous Materials Information System (WHMIS) is a nationwide s y s t e m p r o v i d i n g i n f o r m a t i o n on hazardous materials used in the workplace. WHMIS recognizes the interests o f workers, employers, suppliers, and regulators— balancing the worker’s right to know about hazards with industry’s right to protect confidential business information. Exposure to hazardous materials can cause or contribute to a variety of health effects such as irritation, burns, sensitization, heart ailments, k i d n e y a nd d l u ng d a m a g e, a nd cancer. Some materials may also be safety hazards that c a n contr ib ute t o fires, e x p l o s i o n s , and other accidents if improperly stored or handled. The seriousness of these problems and the lack of information available to employers and employees prompted the federal, provincial, and territorial governments to implement WHMIS in 1988 to reduce the incidence of illness and injury caused by hazardous materials in the workplace. WHMIS is a system of information delivery with three key elements: • Labels on hazardous materials and their containers. Labels immediately alert employers and workers to the dangers of products and provide basic safety precautions. • Material Safety Data Sheets (MSDSs). These technical bulletins provide detailed information on the hazards of the product as well as precautionary measures and first aid procedures for immediate response. • W o r k e r E d u c a t i o n a n d T r a i n i n g . With these programs,

workers receive the instruction on

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procedures that they need to work safely around or near hazardous materials. WHMIS also includes mechanisms for ruling on claims by suppliers and employers to withhold certain information from labels and MSDSs as confidential business information (CBI or trade secrets), and for appeals to these rulings.

WHMIS Hazard Symbols There are eight WHMIS hazard symbols. Employers must train workers to recognize these symbols and to know what they mean.

CLASS A: COMPRESSED GAS This class includes compressed gases, dissolved gases, and gases liquefied by compression or refrigeration.

CLASS B: FLAMMABLE AND COMBUSTIBLE MATERIAL This class includes solids, liquids, and gases capable of catching fire in the presence of a spark or open flame under normal working conditions.

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CLASS C: OXIDIZING MATERIAL

These materials increase the risk of fire if they come in contact with flammable or combustible materials.

CLASS D: POISONOUS AND INFECTIOUS MATERIAL Division 1: Materials Causing Immediate and Serious Toxic Effects

These materials can cause death or immediate injury when a person is exposed to small amounts. Examples: sodium cyanide, hydrogen sulphide.

CLASS D: POISONOUS AND INFECTIOUS MATERIAL Division 2: Materials Causing Other Toxic EFFECTS

These materials can cause life- threatening and serious long-term

health problems as well as less severe but immediate reactions in a person who is repeatedly exposed to small amounts.

CLASS D: POISONOUS AND INFECTIOUS MATERIAL Division 3: Bio hazardous Infectious MATERIAL

These materials contain an organism that has been shown to cause disease or to be a probable cause of disease in persons or animals.

CLASS E: CORROSIVE MATERIAL

This class includes caustic and acid materials that can destroy the skin or eat through metals. Examples: sodium hydroxide, hydrochloric acid, nitric acid

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CLASS F: DANGEROUSLY REACTIVE MATERIAL

These products may self-react dangerously, for example, they may explode upon standing or when exposed to physical shock or to increased pressure or temperature, or they emit toxic gases when exposed to water.

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