Wang_h_Lab4

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Jan 9, 2024

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Spring 2023 Lab 4 Report MSE 1500L 1 1. Pb-Sn phase diagram a. Create a landscape-oriented section and create a single figure containing all 7 Pb-Sn cooling curves collected by your section. Each plot should be 3” tall and 2.25” wide. Use arrows on each plot to identify the phase transition temperatures present.

Spring 2023 Lab 4 Report MSE 1500L 2 Figure 1. Cooling curves for mixtures of Pb and Sn. A) 0% Sn, B) 20% Sn, C) 40% Sn, D) 62% Sn, E) 75% Sn, F) 85% Sn, G) 100% Sn A) B) C) D) E) F) G)

Spring 2023 Lab 4 Report MSE 1500L 3 b. Summarize the results of your cooling curve analyses by tabulating the temperatures and the phase transition occurring at each temperature for each composition of the alloy. Include the phase transition temperatures shown in Wiley’s Animated Figure 9.8 for these 7 compositions. Table 1. Temperatures and phase transitions occurring for 7 compositions of the alloy compiled from section 4 data and Wiley’s Animated Figure 9.8 Temperature of phase transition for section 4 ( ℃ ) Temperature of phase transition for Wiley ( ℃ ) Transition occurring Composition (wt% Sn) Phase change 1 Phase change 2 Phase change 1 Phase change 2 Phase change 1 Phase change 2 0 326 N/A 327 N/A Melting point α N/A 20 280 180 277 180 Liquid to α + L α + L to α + β 40 246 180 237 180 Liquid to α + L α + L to α + β 62 180 N/A 180 N/A Liquid to α + β N/A 75 192 183 201 180 Liquid to β + L β + L to α + β 85 203 183 215 180 Liquid to β + L β + L to α + β 100 228 N/A 232 N/A Melting point β N/A Compositions with only 1 phase transition occurring have the second phase change marked as not applicable (N/A). Pb is denoted by α, and Sn is denoted by β. L denotes liquid phase. c. Create a phase diagram, 3” tall by 4” wide, by plotting your transition temperatures as data points (y-axis) at each composition (x-axis). Do not connect the data points. Label the phases present in each area of your phase diagram.

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Spring 2023 Lab 4 Report MSE 1500L 4 d. Create another phase diagram, 3” tall by 4” wide, by plotting the transition temperatures read from Wiley’s Animated Figure 9.8 vs composition and label the phases present in each region. Comment on i) differences between these phase diagrams, ii) the areas of the diagram your data could not construct, and iii) any anomalous experimental findings. i) In comparing the phase diagram using experimental data and the phase diagram using Wiley’s Animated Figure data, they are visually similar. Comparing the numerical values of the transition temperatures at each composition, all values between the experimental Figure 2. Transition temperatures at each composition. The phases present are labeled on the diagram. α represents Pb and β represents Sn. Figure 3. Transition temperatures at each composition. Data compiled from Wiley’s Animated Figure 9.8. The phases present are labeled on the diagram. α represents Pb and β represents Sn.

Spring 2023 Lab 4 Report MSE 1500L 5 and Wiley’s Animated Figure differ by an absolute value of less than 10 degrees Celsius. Only for 85 wt% Sn do the values differ by more than 10 degrees at 12 degrees Celsius. ii) The data collected was not able to construct the solidus or the solvus lines for both α (Pb rich solution) and β (Sn rich solution) to indicate the limits of solid solubility. The limits of maximum solid solubility happen at 18.3 and 97.8 wt% Sn, compositions of which were not recorded. iii) In the diagram using Wiley’s Animated Figure data, the eutectic temperature stays constant at 180 degrees Celsius. In the experimental data phase diagram, most of the eutectic temperatures are at 180 degrees Celsius, but for 75 and 85 wt% Sn, the eutectic temperature was found to be 183 degrees Celsius. This is minor as the absolute percent error of 183 degrees Celsius as a result is only 1.67%, but it should be noted that the eutectic temperature should stay constant. 2. Microstructure Analysis a. Create a figure containing the original and the thresholded images used to determine the composition of your steel sample. Keep the aspect ratio of your image constant, but scale each so that they fit side-by-side in one figure. Figure 4. Image of original sample (left) and image of the sample after threshold (right). b. Document your composition calculations and identify the type of steel (1018 or 1045) that your sample was made from. Research the typical range of carbon content in each of these steel alloys. Provide a complete citation of the source or sources you consulted. Do your results fall within these typical ranges? For plain-carbon steels, the least significant two digits in the number indicate the weight percent carbon in each alloy divided by 100. Therefore, for 1018 steel, the weight percent of carbon would be 0.18% and for 1045 steel, it would be 0.45 wt% carbon (Professor Choudhury Lecture 26). However, the acceptable range of carbon content for 1018 steel is 0.15-0.20 wt% C (McHone Industries). The acceptable range of carbon content for 1045 steel is 0.43-0.50 wt% C (AZO Materials). After performing analysis on the sample image, it was found that the mass fraction of pearlite in ferrite was 59.591% or 0.59591. At 0.76 wt% C,

Spring 2023 Lab 4 Report MSE 1500L 6 100% composition of pearlite occurs. Using the lever rule, the wt% C (C 0 ) in the sample can be calculated by using the following formula: 𝑊 𝑝𝑒𝑎𝑟𝑙𝑖𝑡𝑒 = 𝐶 0 − 𝐶 𝛼 𝐶 𝑒 − 𝐶 𝛼 Where C 0 is the wt% C at the sample ’ s composition, C α is the wt % C at maximum solubility of α ferrite, 𝐶 𝑒 is the wt% C at the eutectoid, where the composition of the sample is 100% pearlite. 0.59591 = 𝐶 0 − 0.022 0.76 − 0.022 𝐶 0 = 0.46 𝑤𝑡% 𝐶 As shown, the wt% C of the sample is found to be 0.46 which falls in the acceptable range for 1045 steel, so the identity of the sample is 1045 steel. 1018 steel carbon content source: https://www.mchoneind.com/carbon-steel-grades- chart/#:~:text=A%20piece%20of%201018%20steel%20contains%200.18%25%20carbon.,all owable%20carbon%20range%20of%200.15-0.20%25%20for%20this%20grade. 1045 steel carbon content source: https://www.azom.com/article.aspx?ArticleID=9153 3. Hardness profile a. Create a 3” by 3” plot of the Rockwell hardness (y-axis) versus distance from the quenched end (x-axis) for each Jominy bar sample. 15 25 35 45 55 0 10 20 30 40 Hardness (RF) Distance (mm) Figure 5. Rockwell hardness versus distance from the quenched end for 1045 steel. Hardness measured on Rockwell C scale.

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Spring 2023 Lab 4 Report MSE 1500L 7 b. Quantitatively compare the hardness profiles for the 1045 and 4140 steels. In general, 4140 steel has higher hardness measurements compared to 1045 steel. Although the first hardness measurement closest to the quenching surface for 1045 steel (highest 56.10 RF) is higher than any of the hardness measurements for 4140 steel (highest 52.30 RF), 1045 steel experiences a sharp decline in hardness values and ultimately drops to 19.60 RF. On the other hand, 4140 steel has relatively high hardness near the surface due to the effects of heat treatment (quenching). The hardness measurements for 4140 steel experience a more gradual decline than 1045 steel and ultimately drops to 36.90 RF, which is higher than 1045 steel. The difference in hardness is due to the composition of the alloys. 1045 steel contains no other alloying elements, so it is softer and more ductile than 4140 steel which does contain alloying elements, specifically chromium and molybdenum. c. Why is knowing the hardenability of a material important? Provide an example of an application where this information would be used in the design of a component. It is important to know the hardenability of a material because it helps predict how the material will respond to heat treatment processes and how it will affect the resulting microstructure and mechanical properties of the material. Using the hardenability of a material, the appropriate heat treatment process can be used to achieve the desired microstructure and mechanical properties for a given application. For example, in the design of a component like a gear, the hardenability of the material must be considered to ensure that the gear will have the necessary strength and wear resistance over time. If the material has low hardenability, it is not possible to achieve the desired hardness and strength through heat treatment, which would compromise the performance and reliability of the gear. Contrary, if the material has high hardenability, it may be possible to achieve the desired properties with a less severe quenching process, reducing the risk of distortion or cracking during heat treatment. 35 40 45 50 55 0 10 20 30 40 Hardness (RF) Distance (mm) Figure 6. Rockwell hardness versus distance from the quenched end for 4140 steel. Hardness measured on Rockwell C scale.