Lab_3_

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Dec 6, 2023

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Introduction to Material Technology Laboratory Report Lab Course Number & Instructor 2920:142-013 Instructor Use Author Taylor DaGrava, Deleno Domenico, William Korecky Team Number Team 4 Grade Lab Activity Number & Title (Draft or Final) Lab 3 Date Submitted 4/3/2020

Description To investigate the stress/strain (Force/Deflection) and to determine the Ultimate Strength, Yield Strength, Modulus of Elasticity, Percent Elongation, Percent Reduction in Area, and Toughness and Resilience. Measure and record the initial and final specimen dimensions. Record the deflection at varying applied loads on the Instron Tensile Test Machine. Compare Ultimate tensile strength in this lab to estimated results using hardness data collected in Laboratory 5. Procedure Measure and record the width of the initial gage (narrow) section (Wo) and the thickness (To)). Use inches for all measurements. Record these values on the worksheet on p. 4 to be shared with the other lab team, collect corresponding data on other sample from that team Calculate the initial cross-sectional area Pencil a line at the centerline of the length of the narrow width. Pencil two lines each 1” on either side of the above centerline, along the length of the narrow width. The marks 2” apart will be used to align the extensometer on the specimen as well as serve as the gage length, Lo. Overwrite the pencil lines with a fine black permanent marker Place the specimen in the tensile test grips with the black lines on the left and resting against the back stop. Center specimen vertically in the grips. Tighten lower grip then upper grip, so the specimen does not move during the tensile test. Attach the extensometer to the specimen carefully, so that the attachment blades on the extensometer align with the two pencil lines that are 2” apart and the knife edges do not scratch the specimen. The instructor will run the computer to conduct the tensile test, while the students are observing the tensile test specimen distortion and computer plots of stress vs. strain and load vs. elongation. When the test is paused, the instructor will have the students remove the extensometer before resuming the test. Use care again to prevent scratching the specimen. Students will receive the raw data files of the two tensile tests in an email from the instructor. These are CSV files that can be opened in EXCEL. Students will use EXCEL to determine the tensile test properties of the two materials After testing, fit the ends of the fractured specimen together and measure the final gage length (Lf), width (Wf), and thickness (Tf). Record these values on the worksheet on p. 5 to be shared with the other lab team, collect corresponding data on other samples from that team on your worksheet. Calculate the final cross-sectional area Calculate % elongation and % reduction in area Equations:

Results Specimen: Wo To Lo Ao Wf Tf Lf Af Brass .500 .186 2 .093 .415 .162 2.452 .067 Aluminum .501 .193 2 .097 .458 .165 2.197 .076 Specimen: % Elongation % Reduction in Area Brass 22.6 27.7 Aluminum 9.9 21.8 Specimen: Elastic Modulus (psi) 0.2 % offset yield strength (psi) Ultimate tensile strength (psi) Modulus of resilience (psi) Modulus of toughness (psi) Brass 2.81 x 10 6 52500 62500 262.5 2363 Aluminum 1.91 x 10 6 37500 41800 112.5 3640 Aluminum Graphs:

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Brass Graphs:

Pictures of Test Specimens: Aluminum:

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Conclusions We found that the brass withstood a much higher amount of stress and was more elastic than the aluminum. This was apparent in the amount the brass stretched compared to the aluminum before fracturing. This also lines up when viewing our graphs, where the stress-strain slope of the brass is much higher than the aluminum’s. Compare the measured ultimate tensile strength (UTS) to the value predicted from hardness measurement taken in Lab 5: Compared to Lab 5 the ultimate tensile strength for brass (estimated at 63,000 psi) matched very closely to what we found in our test. The Aluminum’s estimated tensile strength was unable to be determined in Lab 5; however, the ASM Material Data sheet estimated it at 45,000 psi which was close to the data we recorded. Compare the elastic modulus to the value given for the material in Table B-1 of the text or in Reference 3:

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The elastic modulus of Aluminum is close to the one in the table, as the one in the table is a minimum. The brass however, does not match the average listed in Reference 3. Identify possible sources of difference of values for UTS and elastic modulus from referenced data: The different sources for the values used between the table and the data recorded is due to the fact that the table uses minimum values as opposed to test values with possible error and a wider range of possible answers. References ASTM E8 “Standard Test Methods for Tension Testing of Metallic Materials” Fundamentals of Materials Science for Technologists, 3rd Edition; Larry Horath, Waveland Press, Inc., 2019, Table B-1 https://amesweb.info/Materials/Modulus-of-Elasticity-Metals.aspx (use for brass) http://asm.matweb.com/search/SpecificMaterial.asp? bassnum=MA6061T6

Appendices

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Team Number 4 Sample Brass W o (in.) 0.500 T o (in.) 0.186 W f (in.) 0.415 T f (in.) 0.162 L f (in.) 2.452 Team Number 3 Sample Aluminum W o (in.) 0.501 T o (in.) 0.193 W f (in.) 0.458 T f (in.) 0.165 L f (in.) 2.197

Lab_3_

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