Team-19_Lab-1_Tensile_Test

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TENSILE TEST OF 1018 STEEL AND 6061-O ALUMINIUM ALLOY Engineering Materials I MCG 2360[B] Laboratory Report Lab 1: Tensile Test Team #19 Student Number Name 300241579 Gautam Mehta 300298485 George Lai 300298002 Phone Thant Htet 300293604 Ryan Gorodezky Experiment Date: October 20, 2023 Date Submitted: November 3, 2023 Professor: Dr. Nafisa Bano TA: Behrang Asghari Shirvani Faculty of Engineering Department of Mechanical Engineering 2023

1 Abstract This laboratory experiment sought to understand and compare the stress-strain relationships between two metallic materials: 6061-O annealed aluminum alloy and 1018 annealed steel. A tensile testing machine will apply stress onto the two specimens of different properties until both fail in the way of necking. Utilizing the ASTM E-8 standards for sample design and testing, each material's mechanical properties, including elastic modulus, yield strength, ultimate tensile stress, reduction in area, and elongation, are assessed. An emphasis was placed on keeping consistent testing procedures to ensure comparability. During the experiment it was noted that the steel had a larger tensile strength and a larger ductility because it was able to go under more stress before starting to plastically deform and start necking than the aluminium specimen. Furthermore, when the steel specimen broke there was a loud noise while for the aluminium it was quiet. The results of this lab will contribute to a greater understanding of the mechanical behaviours of these metals and it useful for engineering applications that require knowledge of such properties.

2 1. Table of Contents Abstract ........................................................................................................................................... 1 1. Introduction ............................................................................................................................. 1 1.1 Objective .......................................................................................................................... 1 1.1.1 Equipment and Materials .......................................................................................... 2 2. Methodology ........................................................................................................................... 2 3. Results and Discussion ........................................................................................................... 3 3.1 Results .............................................................................................................................. 3 3.2 Discussion ........................................................................................................................ 6 3.3 Sample Calculations ......................................................................................................... 7 4. Conclusion .............................................................................................................................. 9 References ..................................................................................................................................... 10 Appendix ......................................................................................................................................... 8

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LAB 1: TENSILE TEST 1 1. Introduction Stress can be described as the internal resistance to deformation by external load and strain would be the amount of normalized material displacement due to stress. To understand the critical material properties, it is important to understand the relationship of stress-strain. Material properties such as stiffness of the material (i.e., Elastic modulus), the point of change from elastic deformation to plastic deformation (i.e., yield strength) and the amount of plastic deformation that the material can undergo before failure (i.e., ductility) are important properties to consider when choosing a material for application. This lab report will compare the two metallic materials: 1018 Steel and 6061-O Aluminium Alloy and analyze how mechanical properties such as carbon content and crystallinity leads to changes in the resultant mechanical properties. The lower density, non-ferrous aluminium alloy 6061-O will be compared to higher density, ferrous, low-carbon steel AISI 1018. Both specimens have been subject to annealing. The material test will be using the guidelines set by the American Society for Testing and Materials (ASTM) E-8 specifications. The test will be supplying data on the force applied to the sample during tension and its relationship to the elongation of the sample during its transition from elastic to plastic deformation followed by failure. 1.1 Objective The objective of this lab report is to compare the stress-strain relationship between two varied materials by using a screw based “Tension testing of metallic materials”. The data from the experiment such as elastic modulus, yield strength, ultimate tensile stress, reduction in area and elongation will be used to relate to the composition of the metals.

LAB 1: TENSILE TEST 2 1.1.1 Equipment and Materials To apply stress, the Instron Universal Testing Machine equipped with a screw tension test apparatus will be used. Samples of the test material will be prefabricated into cylindrical specimens in line with the ASTM Standard E-8 for the “Tension testing of metallic materials”. 2. Methodology Three samples of both AISI 1018 steel and 6061-O aluminum alloy are collected. Before testing, precise measurements were taken, specimen length, the total length of the sample; gauge length, the specific length of the cylinder being tested; and gauge diameter, denoting the diameter of the inner cylinder under examination. The samples of AISI 1018 were securely screwed into the Instron Universal Testing Machine. The testing began with samples progressing through the stages of elastic modulus, elastic deformation, plastic deformation and then finally, failure. Records are taken by the Instron and then these steps repeated using samples of 6061-O aluminum. Upon completion of the testing phase, the now fractured samples have these measurements recorded: specimen length; gauge length; gauge diameter at the shoulder, where the cylinder tapers up to the threads; gauge diameter at the fracture. Lastly, recorded numbers and measurements are formulated into results where conclusions can be drawn.

LAB 1: TENSILE TEST 3 3. Results and Discussion 3.1 Results This section of the lab report will present the results of the tensile strength test of the two materials: AISI 1018 Steel and 6061-O Aluminum Alloy. The results will cover stress-strain curves of the two different materials each tested with 3 samples. The material properties such as the Elastic Modulus, Yield Strength, Ultimate Tensile Strength, Reduction in Area, and Elongation will be calculated based on the data points plotted on the stress-strain curve of the respective materials and the values will be used to find the mean and standard deviation for more accurate representation. Figure 3.1: Stress-Strain Curve of AISI 1018 Steel Figure 3.1 shows the stress-strain cure of the tested steel specimen. From the graph of steel, Steel 3 is deemed as an outlier since the curve is very distant to the remaining 2 curves of Steel 1 and 2. Among the two samples, the graph of steel 1 has clear … Therefore, steel 1 is chosen to be the representative of the material.

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LAB 1: TENSILE TEST 4 Table 1: Properties of AISI 1018 Steel Property of Steel Mean Standard Deviation Elastic Modulus (E) 10007.96592 +/- 1911.111063 Yield Strength (σ y ) 299.0981035 +/- 15.37825599 Ultimate Tensile Strength (UTS) (MPA) 456.8425362 +/- 10.62442253 Reduction in Area 59.89% +/- 0.77057 Elongation 41.34% +/- 0.36037018 Figure 3.2: Stress-Strain Curve of 6061-O Aluminum From Figure 3.2, the curve for Aluminum 3 will be considered as an outlier since it has vastly different data points comparted to the graph of Al 1 and Al 2. For 6061-O Aluminum, the graph of Al 1 will be taken as a representative of the material since it ’s point of failure is approximately in the range of the average points of failure of the other two curves.

LAB 1: TENSILE TEST 5 Table 2: Properties of 6061-O Aluminum Property of Aluminum Mean Standard Deviation Elastic Modulus (E) 2736.461901 +/- 410.41171659 Yield Strength (σ y ) 29.81641496 +/- 6.58086175 Ultimate Tensile Strength (UTS) (MPA) 109.8707964 +/- 12.30482598 Reduction in Area 79.2% +/- 0.428548 Elongation 42.48% +/- 0.17204651 Figure 3.3: Stress-Strain Curve Comparison of Steel and Aluminum The above figure is a graph plotted using the representatives of both materials for the purposes of comparison and understanding the different material properties of steel and aluminum. Gauge Diameter Gauge Length Sample Initial (mm) Final (mm) Initial (mm) Final (mm) Aluminum 1 12.5 5.72 50 71.35 2 12.5 5.76 50 71.23 3 12.5 5.62 50 71.14 Steel 4 12.5 8.02 50 70.65

LAB 1: TENSILE TEST 6 5 12.5 7.89 50 70.46 6 12.5 7.84 50 70.9 3.2 Discussion Based on the stress-strain graphs, a prominent distinction in the material behavior of steel and aluminum is evident. Steel showcases a superior yield strength relative to aluminum. This becomes especially pronounced when comparing the average yield strength; with aluminum registering at 29.82MPa and steel at 299.1MPa. Consequently, once these materials surpass their yield points, they exhibit plastic deformation. Aluminum enters this phase of deformation considerably sooner, due to its lower yield strength. The characteristics of steel become even more pronounced when examining its behaviour near its ultimate tensile strength. Steel exhibits a brittleness, evidenced by its almost immediate necking followed by a sharp and loud fracturing. To compare, aluminum, which possesses a more ductile nature, necks gradually upon reaching its ultimate tensile strength and continues to deform plastically until the point of fracture. The fracture process of aluminum is clearly a quieter and more prolonged breakage compared to the abruptness of steel. Elastic modulus serves as a measure of a material's resistance to elastic deformation and is quantified as the ratio of stress to strain. For this test, the elastic modulus stood at 2736.46Pa for aluminum and 10007.97Pa for steel. A material with a high elastic modulus will resist deformation more effectively, meaning it will exhibit lesser deformation for the same applied force relative to materials with a lower modulus. Introducing an extensometer to the test setup could offer enhanced precision in strain measurements. The device measures the elongation and contraction of a sample directly, making it possible to determine material properties with a higher degree of accuracy. Properties like yield

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LAB 1: TENSILE TEST 7 strength, modulus of elasticity, and Poisson's ratio would be directly impacted using an extensometer. Fracture surface analysis provides insightful data regarding the nature of material failure. Observations from the fracture surfaces can reveal patterns of deformation, potential inclusions, or voids that might have contributed to premature failure. Specific anomalies or patterns, such as dimples, could indicate ductile failure, while flat and shiny surfaces might point towards brittle fractures. When considering the percentage elongation, it was found that aluminum, with a value of 42.48%, surpasses steel, which was at 41.34%. This indicates that aluminum exhibits a greater capability for deformation before reaching the point of failure, reinforcing its inherent ductility compared to steel. Furthermore, the percent reduction, a crucial indicator of ductility, was determined to be 59.89% for steel and 79.2% for aluminum. The data implies that aluminum, in the event of failure, undergoes a more substantial reduction in its cross-sectional area than steel. Finally, it's imperative to recognize potential sources of error that could have influenced the results. These might encompass inaccuracies in measurements, imperfections inherent in the steel manufacturing process, or miscalculations. Ensuring rigorous adherence to experimental protocols and using precise instruments can help mitigate these errors in future tests. 3.3 Sample Calculations ***Note - Data for sample calculations can be found in the spreadsheet*** An example of each type of calculation will be presented with accuracy of 8 decimals. Sample 1 – AISI 1018 Steel: E = Elastic Modulus = Stress / Strain

LAB 1: TENSILE TEST 8 P 1 = (0 , 0) P 2 where stress is at its highest before its first decline = (0.03484136 , 315.0102757) E Steel 1 = Slope = (y 2 - y 1 ) / (x 2 - x 1 ) = (315.0102757 - 0) / (0.03484136 - 0 = 9041.273811 Mean = Sum of Samples / # of Samples Mean E-Steel = (9041.273811 + 8305.528805 + 12677.09513) / 3 = 10007.96592 Std. Deviation = SQRT[ (Σ( x i – Mean) 2 ) / # of Samples ] Std. Deviation E-Steel = SQRT[((9041.273811 - 10007.96592) 2 + (8305.528805 - 10007.96592) 2 + (12677.09513 - 10007.96592) 2 ) / 3] = +/- 1911.111063 % Reduction in Area = ((Initial Area – Final Area) / Initial Area) * 100 Area of Initial Cylinder = π(d/2) 2 = π( 12.5mm/2) 2 = 122.718463mm 2 Area of Fracture Steel 1 Cylinder = π(d/2) 2 = π( 8.02mm/2) 2 = 50.51712403mm 2 Mean = (50.51712403 + 48.89268501 + 48.27496935) / 3 = 49.22825946mm 2 Elongation = 𝐿𝑓 – 𝐿0 𝐿0 ∗ 100 = 71.35−50 50 ∗ 100 = 42.7

LAB 1: TENSILE TEST 9 4. Conclusion From the collected data and the generated stress-strain graphs, a clear understanding of the behavior of steel and aluminium under tensile stress was obtained. The results indicate that steel not only possesses a superior strength compared to aluminium but also displays a higher degree of brittleness. This shows that inducing plastic deformation in steel demands a substantially greater force than what's required for aluminium. The observed behavior proves the superiority of steel's strength over aluminium, making it an ideal choice for applications demanding high stress loads. Furthermore, the toughness of steel, as gauged by the larger area beneath its stress-strain curve, surpasses that of aluminium. This can be attributed to steel's elevated yield strength and ultimate tensile strength. The prolonged duration to fracture and extended necking observed in aluminium, when contrasted with steel, reveals a notable difference in their respective cross- sectional areas, both before and after the test. Specifically, aluminium exhibited a more significant change in cross-sectional area from its original state, due to its ductile nature. Looking at the fracture points of both materials further proves the higher ductility of aluminium as opposed to steel. Potential sources of error in this experiment include imperfections originating from the manufacturing process of the steel and aluminium specimens. Additionally, measurement discrepancies, potentially arising from gauging the samples pre and post the tensile test, could skew the results. To enhance the accuracy and minimize the margin of error in future iterations of this lab, it's important to take multiple measurements, followed by a comparative analysis to ensure precision and reliability.

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10 References • Lambros S. Athanasiou, Dimitrios I. Fotiadis, Lampros K. Michalis, 10 - Structure and Mechanical Behavior of Atherosclerotic Plaque, Editor(s): Lambros S. Athanasiou, Dimitrios I. Fotiadis, Lampros K. Michalis, Atherosclerotic Plaque Characterization Methods Based on Coronary Imaging, Academic Press, 2017, Pages 181-198, ISBN 9780128047347, https://doi.org/10.1016/B978-0-12-804734-7.00010-5 . • N. Bano, B.A. Shirvani, X. Xie, Data - Lab 1 - Tensile Test, University of Ottawa, Department of Mechanical Engineering, 2023 • Siplyarsky, Alex. “The Importance of an Extensometer in Materials Testing.” NextGen Material Testing , 9 Oct. 2019, www.nextgentest.com/blog/the-importance-of-an- extensometer-in-materials- testing/#:~:text=An%20extensometer%20is%20an%20accessory,they%20can%20be%20 clearly%20visible .