maae2700-lab-2-lab-2-practical

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Carleton University *

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Dec 6, 2023

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lOMoARcPSD|30545641 MAAE2700 Lab 2 - Lab 2 practical Engineering Materials (Carleton University)

1 lOMoARcPSD|30545641 Lab Report Template Lab 2 – Cold Working & Annealing 1. Summary 2 micrographs were provided where one was the 70% Cold worked ingot iron while the other one was the 70% annealed iron sample. 3 specimen were provided which were brass , SAE 1020 steel and an unknown sample. The hardness and initial height of the samples were measured. After that cold working was performed on the samples using a press. Different tons were applied to the samples. Then the deformed height and the hardness of each sample were measured again. Then using a formula the cumulative cold work ( %) were calculated at each stage. After that , annealing was performed on the samples at 300 C for 15 min , 500 C for 15 min and 800 C for 15 minutes . At last after plotting the graph, it was concluded that the unknown sample was SAE 1045 Steel. 2. Results and Observations 2.1 Record the hardness and height of each sample in Table #1 provided below. Ensure to indicate the proper unit of measure for all data in the table. C scale was used for the initial hardness as it was more accurate and was converted to HB. Table 1: Hardness, height, percent cold work (%CW), and tensile strength (TS) values Sample Material Condition Measurement or Calculation Units Brass SAE 1020 steel Unknown steel Initial sample Hardness Kg/mm^2 4 194.39 230 Height mm 7.94 13.32 7.8 5 tons Hardness Kgmm^2 166 -- -- Height mm 7.9 -- -- %CW % 0.504 -- -- Tensile Strength 572.7 -- -- 10 Tons Hardness Kgmm^2 170 196.97 260 Height mm 7.43 13.2 7.2 %CW % 6.42 0.9 7.7 Tensile Strength MPa 586.5 583.03 897 20 Tons Hardness Kgmm^2 212 207.81 290 Height mm 5.09 10.56 4.2 %CW % 35.89 20.72 46.2 Downloaded by Udbhav Jha (jhaudbhav26@gmail.com)

lOMoARcPSD|30545641 Tensile Strength MPa 731.4 615.11 1000.5 30 Tons Hardness Kgmm^2 -- 209.64 330 Height mm -- 7.43 3.0 %CW % -- 44.22 61.5 Tensile Strength MPa -- 620.52 1138.5 After annealing at 300 C for 15 min. Hardness Kgmm^2 203 199.8 290 Tensile Strength MPa 700.35 591.41 1069.5 After annealing at 500 C for 15 min. Hardness Kgmm^2 163 -- -- Tensile Strength MPa 562.35 -- -- After annealing at 800 C for 15 min. Hardness -- 137.7 200 Tensile Strength -- 407.59 690 2.2 Attach the micrographs of the 70%CW, and 70%CW + annealed sample in the space provided below. Outline a grain in each photograph and indicate which grain is “deformed” versus “annealed”. Indicate the direction of applied load for the deformed sample. Sample #1 – 70% Cold Worked Ingot Iron Additional information Compressed grains Grains are flat. Grain pattern follows a uniform shape and size. Sample #2 – 70% Annealed Ingot Iron Additional Observations Typical grain shape of iron ingot. Larger grain size 2 Downloaded by Udbhav Jha (jhaudbhav26@gmail.com)

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1 lOMoARcPSD|30545641 Non uniform shape 2.3 Record your observation of the hot rolled and cold rolled steel strips at your workbench. Make comments about the surface appearance, edge definition, and thickness of each sample. Using your engineering judgment, indicate which sample you believe is cold rolled and which sample you believe is hot rolled based on the bend test and your observations. 2.4 One of the steel strips is light grey while the other strip is dark grey. The edge of the light grey one is more polished than the dark grey one. Both steel strips have roughly the same thickness. The light grey steel strip is the cold rolled steel strip because it is harder, it has an increased tensile strength, and it is less ductile as compared to the dark grey steel strip which is the hot rolled steel strip. 2.5 Calculate the total percent cold work (%CW) for all samples and place the values in Table #1 above. Show a sample calculation in the space provided below. Unknown steel Initial sample %CW = [(h o ‐ hf ) /h o ] x 100 %CW = [(7.8 – 7.2)/7.8] * 100 = 7.7 % Downloaded by Udbhav Jha (jhaudbhav26@gmail.com)

lOMoARcPSD|30545641 2.6 Calculate the tensile strength (TS) for all samples and place the values in Table #1 above. Show a sample calculation in the space provided below. Unknown steel 10 tons 24.9 C = 260 HB TS unknown sample = 260 HB * 3.45 = 897 MPa = 897 MPa 2.7 Plot the following relationships for each of the three materials (Brass, SAE 1020 steel, and the unknown steel). Attach your plots in an Appendix at the end of this template. Ensure that the x and y axes are properly labeled, and a legend is constructed for each plot in order to distinguish the curve for each material. 2.7.1 Plot hardness versus percent cold work. 2.7.2 Plot hardness versus annealing temperature. 2.7.3 Plot tensile strength versus percent cold work. 2.7.4 Plot tensile strength versus annealing temperature. 2.7 In the space below, identify the unknown steel sample and provide a short paragraph to justify your answer. The unknown sample is SAE 1045 Steel. It has a higher tensile strength and hardness than brass. The slope of hardness against CW also closely follows the SAE 1045 steel. The unknown sample also behaves exactly like the same as the SAE 1045 steel for the annealing process as seen in the hardness vs annealing temperature in the appendix. 3. Provide answers to the questions given by the TA and attach them to the end of this template. Explain Coldworking, and Hot working process, along with their different types, advantages, and limitations. Coldworking is the process that occurs at ambient temperature, and it involves deforming a metal or alloy through mechanical forces without the need for significant heat. Some examples are cold rolling and cold drawing. Hot working involves the deformation of metals and alloys at very high temperatures. Some examples are forging and hot rolling. Advantages of cold working is that it improves surface finish, it enhances the strength and hardness of the sample and there is no risk of degradation due to high temperatures and their limitations are to achieve the desired shape, multiple passes are required. Cold working processes can be limited in terms of the complexity of the shapes they can achieve. There is also 4 Downloaded by Udbhav Jha (jhaudbhav26@gmail.com)

1 lOMoARcPSD|30545641 risk of cracking especially when dealing with high strength alloys. Advantages of hot working is that they are easier to achieve complex shapes, ductility is improved and there is less risk of cracking, and it is suitable for materials that are difficult to deform at room temperature. The limitations are the surface finish may be rough, metal oxidation and scaling can occur at high temperatures and the need for reheating can be energy intensive. Discuss Annealing process in depth (Heat Treatment Process) Annealing is a heat treatment process used to modify the physical and mechanical properties of metals and alloys to increase ductility and reduce hardness and become suitable for various applications. The cooling rate depends on the type of metals. The heating process will make atoms move in the crystal lattice and the number of dislocations reduces which lead to change in ductility and hardness. Then, as it cools recrystallization takes place. The grain size and composition depend on heating and cooling rates. Annealing works in 3 stages which are recovery stage, recrystallization stage and the grain growth stage. In the recovery stage, the metal is heated to a specific temperature. The temperature is chosen based on the material’s composition. The metal is heated until the internal stresses are relieved. The second stage is recrystallization where the metal is held at the annealing temperature for some time meaning that new, smaller grains will be formed without any residual stresses which will replace the old ones. This will help reduce hardness and increase ductility. The third stage is grain growth where the material is slowly cooled after it has soaked at the annealing temperature. Slow cooling will lead to the growth of larger grains, which can further lead to mechanical properties. Explain different hardness measurement devices used in our labs. In the experiment, the Victor hardness device was used . The victor hardness device is designed to access the hardness of a material by measuring the depth and size of indentation created under a specific load. Brinell hardness device was used. It is a method of measuring the diameter of an indentation made on the material’s surface under a known load. The Rockwell C hardness device was also used. It is a method at first, a small push is applied to make sure everything is tight and then a big push is applied on the material’s surface to make a dent. After that the push is taken away and a gauge Is used to measure how deep the dent is. References https://www.twi-global.com/technical-knowledge/faqs/what- is annealing#:~:text=Annealing%20is%20a%20heat%20treatment,amount%20of%20time%20before %20co oling . Downloaded by Udbhav Jha (jhaudbhav26@gmail.com)

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lOMoARcPSD|30545641 6 Downloaded by Udbhav Jha (jhaudbhav26@gmail.com) 0 50 100 150 200 250 300 350 50 0 100 150 200 250 Hardness CW Graph of Hardness(kgmm^2) against CW(%) Brass SAE 1020 Steel Unknown sample Linear (Brass) Linear (SAE 1020 Steel) Linear (Unknown sample)

1 lOMoARcPSD|30545641 Downloaded by Udbhav Jha (jhaudbhav26@gmail.com) 0 50 100 150 200 250 300 350 1000 800 600 400 200 0 Hardness Annealing temperature( C) Graph of Hardness (Kgmm^2) against annealing temperature ( C) Brass SAE 1020 steel Unknown sample Linear (Brass) Linear (SAE 1020 steel) 0 200 400 600 800 1000 1200 0 200 400 600 800 Tensile strength CW Tensile strength(MPa) against CW(%) Brass SAE 1020 Steel Unknown sample Linear (Brass) Linear (SAE 1020 Steel) Linear (Unknown sample)

lOMoARcPSD|30545641 8 Downloaded by Udbhav Jha (jhaudbhav26@gmail.com) 0 200 400 600 800 1000 1200 200 400 600 800 1000 0 Tensile strength Annealing temperature ( C) Tensile Strength(MPa) against annealing temperature (C) Brass SAE 1020 Steel Unknown sample Linear (Brass) Linear (SAE 1020 Steel)

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