Final_Project_Report

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MENG 3331 Materials Science Department of Mechanical Engineering Nov. 27, 2023, Statesboro, Georgia, USA Technical Report 7 WELD ANALYSIS FINAL PROJECT Bryce Cone Georgia Southern University Sparks, Georgia, USA Dylan Butler Georgia Southern University Albany, Georgia, USA Scott Rhodes Georgia Southern University Warner Robins,GA,USA Lawrence Almeter Georgia Southern University Dearing, GA, USA A BSTRACT In the following lab a series of experiments were conducted on a weld sample. These experiments consist of a metallography, a tensile test, and a hardness test experiment. In the following experiments, two pieces of welded samples were provided. The first weld sample was cut on both sides of the weld then split directly down the middle and placed in an epoxy resin. This piece was used for the metallography and the hardness portion of the lab. For the metallography portion of the lab the sample metal in the resin was sanded against various pieces of sandpaper while rotating 90 degrees in between each piece of sandpaper. After the initial sanding process the metal undergoes the process of polishing. This allows the metal to gain a mirror finish. This portion of the metallography experiment took quite a bit of time due to the delicacy. An etching process is then taken place with an acidic chemical called Nital. This sample is then placed under a microscope to view the fusion zone, transition zone, and base metal zone. The photos taken are in a 100x zoom and a 1000x zoom. The next portion of the lab conducted is the hardness portion. For this portion, the sample used in the metallography lab is being placed in the Rockwell Hardness tester. The goal here is to calculate the tensile strength after being given the results of the test. The scale used for this experiment on the Rockwell Hardness Tester is the HRB scale. The sample metal had several tests performed on it and the results of that are 92.5 HRB for the weld, 87 for the HAZ short side, and 79.5 HAZ long side. The results for the area going down the length of the sample are recorded as 82.5, 80, 82, 79, and 78. The final experiment performed was the tensile test. This was the act of placing the second weld sample in the ADMET testing system and recording the results of the test. Once the results are recorded, a calculation to determine the engineering stress. The results of the tensile test were recorded as a range from 28.068 lbF to a max of 7278.000 lbF as shown in Table 4. Tensile Test Calculations N OMENCLATURE ADMET Tensile Testing Machine HAZ Heat Affected Zone HRB Rockwell Hardness B Scale INTRODUCTION This experiment consists of taking two samples of welded 3/16ths inch steel plate samples and performing tensile testing on one sample while performing metallography and hardness testing on the other. To begin, take one sample and cut a perpendicular cross section of the weld and trim down the length to include the HAZ (Heat Affected Zone), Fusion zone, and the unaffected region of the plate. Once the sample is prepared the sample will be set into a mold and suspended in epoxy resin then when the resin is set the sample will be sanded and polished to allow for observation of the microstructures of each zone. After metallography is performed the sample’s hardness will be tested using a rockwell hardness tester observing the hardness of each zone. Metallography can be accredited to Henry Clifton Sorby in the late 19th century [2]. While Rockwell Hardness testing can be credited to Stanley Rockwell and Hugh Rockwell with the creation of the standardized hardness testing machine [3]. The second sample will be used to observe the tensile strength of the weld. The sample will be set into an ADMET tensile tester and secured in place. Then the ADMET tester will be turned on with the software recording all the data and will record until the sample fails. Robert Hooke can be credited with the efforts put forth to standardize the testing of properties of metals [1]. σ = Force Area = F [ N ] A [ mm ¿¿ 2 ]= Stress [ MPa ] ¿ (1) 1 Copyright © 2023 by ASME

ε = Deformation Originallength = ΔL L 0 = Strain (2) E = Stress Strain = σ ε = Youn g ' s Modulus (3) EXPERIMENTAL METHODS The weld test experiment is begun by cutting off excess material using the band saw. To do this mark off two sections about ¾ inch from the weld. Once the excess material is removed, file and grind the edges to make smooth. Now the abrasive saw will be used to cut the weld sample directly in half long ways. Once the sample is in two, one side will be picked to be placed into a cylindrical shaped form and then filled with a resin. Once the resin is set perform the metallography experiment on the cross-section of the weld still exposed on the surface. Performing this includes sanding it down, then polishing and finally acid etching it. Once completed, the sample will be brought under the microscope and analyzed. Under the microscope each microstructure zone of the weld will be looked at. The zones being looked at will include the base metal, fusion zone, HAZ, and transition zone. Next experiment performed on the sample will be the hardness test. Set up the rockwell hardness machine and start performing the hardness B scale test. Multiple hardnesses will be recorded for each zone on the weld sample to analyze how welding affects the hardness of the metal. Finally it will be time to perform the tensile test on the other fully intact weld sample to test how strong the weld is on it. Place the weld sample into the ADMET testing and record the original length,thickness and width. Once started the machine will begin applying a tensile load on the sample until it snaps. Take pictures and obtain the numerical results from the software to then plot the stress-strain curve created from the test. DATA AND R ESULTS The results of the three experiments were as expected. In the metallurgy experiment, the different zones around the weld were extremely clear. In figures 1 and 6, the Martensite phase is clearly visible as the shiny brass material. Around it, the dark pearlite and white ferrite phases are visible as well. Figure 2 displays the transition zone extremely well, and the discoloration from the heat is visible along the edge between the fusion zone and the HAZ. Figures 3 and 4 show the base metal which is unaffected by the heat caused by the welding process. The grain of the metal is still linear with mostly ferrite phase and some pearlite phase. Figure 5 is a photo of the fusion zone or the weld itself. The discoloration from the heat is clearly visible. In the hardness experiment, the hardness was tested at the fusion zone, HAZ, and along the base metal away from the HAZ. The data can be found in Annex A Table 1. The highest hardness was 92.500 HRB in the fusion zone on the weld. The HAZ had the next highest hardness value of 87.000 HRB. The HAZ on the other side of the weld had a much lower value of 79.5 HRB. This lower value could be due to a slower cooling rate on the longer side of the sample. Then going down the length of the base metal, the hardness slowly decreases from 82.5 HRB closest to the HAZ to 78 HRB furthest from the HAZ. A graphical representation of the data is shown in Figure 9. The highest value is at the fusion zone, and the hardness slowly decreases with the increasing distance from the fusion and HAZ. Figure 10 is an image of the weld sample after testing the hardness. In the tensile test, the sample performed reasonably well. The sample did fail at the weld due to a poor fusion between the weld and the base metal. The data and graphs can be found in Annex A. Table 2 contains the weld sample dimensional measurements and calculations. Table 3 shows the first and last ten points of load data from the tensile test as well as calculations to show the stress and strain values. Table 4 contains the calculated values of the UTS, Yield Strength, Young’s Modulus, and elongation percentage. All the values seem reasonable considering the sample failed prematurely due to the poor fusion between the base metal and the weld. The stress strain graph is shown in Figure 9. The curve is reasonable, and it is clear that the curve ends prematurely since the full curve would have been much more gradual in the plastic deformation region. Figure 10 shows the Young’s Modulus calculated from the graph. The values from the tables and graphs align extremely close to the values of 1018 mild steel. So it is likely that the weld samples were made from this steel. The test was done along the length of the entire sample. Figure 11 is an image of the sample in the tensile testing machine before fracture. Figure 12 is a picture of the sample after fracture. Figures 13 and 14 show the fracture more clearly, and it is easier to see the location of the failure which is right along the fusion line between the weld and base metal. Figure 1.Photo of HAZ 1000x Martensite 2 Copyright © 2023 by ASME

Figure 2. Photo of the transition / fusion zone 100x Figure 3. Photo of Base Metal 100x Figure 4. Photo of Base Metal 1000x Figure 5. Photo of fusion zone 100x Figure 6. Photo of HAZ 1000x DISCUSSION Upon completion of the following experiments, it is discovered that the metal is affected in many different ways by the weld. In the metallography portion it is noticeable that the heat of the weld greatly affects the metal as shown in Figure 2. Photo of transition / fusion zone 100x. This photo represents an accurate response to great heat from the welding process. Figure 3. Photo of Base Metal 100x represents the area of the metal that is unaffected from heat because it is far away from the area from where the heat was applied. Figure 5. Photo of fusion zone 100x, this photo accurately shows what the structure of the weld is and how the heat applied to the metal can change crystal formation and it can be strengthened or weakened. Upon conducting the hardness test, it is determined that the metal becomes softer the further away from the weld. The result for the hardness at the weld was 92.500 HRB. The result for the HAZ short side is recorded as 87.000 HRB. The result for HAZ long side is recorded as 79.500 HRB. As the test was taken going down the sample weld from here, it was recorded as 82.500 HRB,80.000 HRB, 82.000 HRB, 79.000 3 Copyright © 2023 by ASME

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HRB, and 78.000 HRB. This might be due to the fact that the further a test performed from the heat applied area, the lesser possibility of the structures were able to be properly aligned. Finally in the tensile test a max force of 7278.000 lbF and a Max Force of 32371.000 N was achieved. With this a Young’s Modulus of 7.990 GPa and Yield Strength 230.000 MPa was calculated. CONCLUSION This experiment was done to see how a weld affects the metal mechanical properties. Using two different weld samples a metallography, tensile, and hardness test were performed. The tensile test showed the sample with a yield strength of 230. MPa and an ultimate tensile strength of 235 MPa. Performing the hardness test on each zone showed a 92.5 HRB on the weld itself, a 87 HRB on the HAZ short side, a 79.5 HRB on the HAZ long side, and an average of 80.3 HRB on the base metal. As the hardness test was performed further away from the weld the metal was recorded to be softer. Upon performing the metallography experiment it was seen that the closer the microscope was moved to the heat affected zones that the metal was heated very hot and cooled very fast. This process formed martensite around the HAZ. R EFERENCES [1] “Robert Hooke.” Encyclopædia Britannica , Encyclopædia Britannica, inc., 24 July 2023, www.britannica.com/biography/Robert-Hooke. [2] Diez, Dionis, and James DeRose. “Metallography – an Introduction.” Science Lab | Leica Microsystems , 5 July 2021, [3] “Rockwell Scale.” Wikipedia , Wikimedia Foundation, 28 May 2023, en.wikipedia.org/wiki/Rockwell_scale. 4 Copyright © 2023 by ASME

A NNEX A T ABLES AND G RAPHICAL F IGURES Table 1. Hardness data Distance [in] Hardness [HRB] -0.0625 87 0 92.5 0.0625 79.5 0.21875 82.5 0.34 80 0.50 82 0.66 79 0.75 78 0.8125 77 Figure 7. Hardness of the Weld Sample Figure 8. Hardness Test on Weld Sample Table 2. Weld Sample Dimensions and Measurements T [in] T [mm ] W [in] W [mm ] A [in] A [mm] GL [in] GL [mm] 0.2 26 5.74 04 1.03 9 26.3 906 5.96 43 151. 493 3.95 5 100.4 57 0.1 87 4.74 98 1.03 9 26.3 906 4.93 50 125. 350 3.95 5 100.4 57 0.2 04 5.18 16 1.03 9 26.3 906 5.38 37 136. 746 3.95 5 100.4 57 A vg 0.2 06 5.22 4 1.03 9 26.3 91 5.42 8 137. 863 3.95 5 100.4 57 St d D 0 0 0.00 00 0.00 00 0.51 60 13.1 070 0.00 00 0.000 0 Table 3. Weld Sample Tensile Test Data and Calculations Read ing Load [lbF]2 Disp [in] Disp [mm] t [s] F [N] σ [M Pa] ε [mm/ mm] 1 28.06 7.31 0.018 0 124 0.9 0.000 5 Copyright © 2023 by ASME

8106 E-04 5674 .85 055 9 1848 3 2 50.68 8396 0.00 1557 0.039 5576 8 0. 5 225 .46 1.6 354 1 0.000 3937 8 3 79.11 179 0.00 2393 0.060 7878 5 1 351 .89 2.5 524 6 0.000 6051 1 4 117.0 0966 0.00 3225 0.081 9220 6 1. 5 520 .46 3.7 752 0.000 8154 9 5 164.1 4514 0.00 4058 0.103 0802 6 2 730 .12 5.2 959 7 0.001 0261 1 6 225.0 1859 0.00 4892 0.124 2624 5 2. 5 100 0.9 7.2 599 9 0.001 2369 7 7 286.6 026 0.00 5725 0.145 4206 5 3 127 4.8 9.2 469 4 0.001 4475 9 8 342.7 3883 0.00 6559 0.166 6028 4 3. 5 152 4.5 11. 058 1 0.001 6584 5 9 396.7 433 0.00 7393 0.187 7850 3 4 176 4.7 12. 800 5 0.001 8693 1 10 447.6 6855 0.00 8227 0.208 9672 2 4. 5 199 1.2 14. 443 6 0.002 0801 7 176 3456. 2854 0.14 6559 3.722 5960 6 87 .5 153 74 111 .51 4 0.037 0566 1 177 3229. 0166 0.14 7393 3.743 7781 4 88 143 63 104 .18 1 0.037 2674 7 178 1403. 7606 0.14 8226 3.764 9363 88 .5 624 3.9 45. 290 0.037 4780 4 9 9 179 - 0.118 4308 0.14 9059 3.786 0942 8 89 - 0.5 268 - 0.0 038 0.037 6887 1 180 0.236 8616 6 0.14 9893 3.807 2768 7 89 .5 1.0 536 0.0 076 4 0.037 8995 7 181 0.236 8616 6 0.15 0725 3.828 4109 4 90 1.0 536 0.0 076 4 0.038 1099 5 182 0.236 8616 6 0.15 1559 3.849 5932 7 90 .5 1.0 536 0.0 076 4 0.038 3208 1 183 0.355 2925 0.15 2391 3.870 7273 4 91 1.5 803 0.0 114 6 0.038 5311 9 184 0.473 7233 2 0.15 3225 3.891 9094 1 91 .5 2.1 071 0.0 152 8 0.038 7420 4 185 0.473 7233 2 0.15 4058 3.913 0678 7 92 2.1 071 0.0 152 8 0.038 9526 6 Table 4. Tensile Test Calculations UTS [MPa] 235 %EL 4 Young's Modulus [MPa] 7990 Young's Modulus [GPa] 7.99 Yield Strength [MPa] 230 Max Force [lbF] 7278 Max Force [N] 32371 6 Copyright © 2023 by ASME

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