Comparison between the Tensile Copper and Aluminum Properties - Report Example

Tensile lab Affiliation TENSILE LAB Within this lab setup, a comparison between the tensile copper and aluminum propertieswas conducted. The changes through each deformation regions for bot copper and aluminum were observed as well. The following report is a study of the young’s modulus of for both Aluminum and Copper. The report does also include the outcomes as well as the gathered data analysis. Summary This laboratory set up got to study the tensile properties for aluminium and copper metals. The following apparatus were used to carry out the experiment: the TecQuipment’s laboratory which is the scale bench top tensile testing machine, the Extensometer and the Dog bone which was shaped in different shaped samples of yellow brass, some cold rolled carbon steel as well as aliminium in long and short lengths. The extensometer was the device used to measure the test specimen extension directly. It was clamped on the specimen and mounted on in the densometer and depended in the principle upon the breaking as well as the remaking of an electrical circuit just as the test specimen was being stretched. The extensometer was not at any time used beyond its yield point. Experiment one set up was as follows: The initial diameter of each specimen was measured. The specimen was clamped on the tensometer and was tightened. The small hand wheel was rotated slightly to refit the locking pin. The digital meter was switched on and its “press to zero buttons” was pressed. The sliding indicator display was set to zero. As the load was slowly increased, the force values showing in the digital meter were recorded. The values of the yield point were observed as well as the ultimate tensile point and the fracture point. The final diameter and length were measured. Experiment 2 set up was as follows: the initial diameter of the specimen was measured. The specimen was mounted to the tensometer and the extensometer mounted to the specimen. The original length between the extensometer’s two clamping points was measured. The digital meters as well as the extensometer were set to zero. Increasing loads were applied while staying right below the yield points. At every load, the force value as well as the extensometer reading was recorded. The recorded data was used for calculations. On each metal, some load was exerted. After calculating aluminium, the following were confirmed: yield stress was 314.47 MPa, the ultimate tensile stress was 341.47MPa, the true stress at fracture was 605.63MPa, the breaking stress was 266.89Mpa, %EL (percentage of elongation) was 15.8 percent and the percentage area reduction was 55.9 percent. The calculation of copper yielded the following results: the yield stress was 255.89MPa, the ultimate tensile stress was 319.40 MPa, the breaking stress was 198.04MPa, the true stress at fracture was found to be 745.84MPa, the percentage of elongation or the %EL calculated to 15.8 percent and the percentage area reduction was 73.4 percent. Within the second part of this experiment, an extensometer was made use of to measure the strain caused elongation within the region of elasticity. For both the copper and the aluminum, a graph for stress against strain was calculated and plotted. The outcome slope was representing the relative stiffness (the elasticity young modulus) for both the copper and the aluminum metals. The young’s modulus of elasticity for the copper material was 156.0GPa. The young’s modulus of elasticity for the aluminum material was 303.0GPa. After comparison between the copper and the aluminum in terms of strength and ductility, interesting correlations between the fracture surfaces and the results measured were observed. In the order of increasing the tensile strength and decreasing of the ductility, copper was ranked higher followed by aluminum. These results do agree with the values of callister. A major difference of between two hundred percent (200%), and three hundred percent (300%) between the calculated values or calculated data and the values that are published was revealed. It proved difficult to select an alloy composition with which to compare the data, however, not many values do correspond in whatever form. The young modulus of elasticity tensile strength, yield strengths as well as the percentage of elongation values for both the copper and the aliminium found in the first experiment and the second experiment were different from the values stated within the Callister text book anywhere from two hundred percent to three hundred percent depending on the alloy of metal that has been chosen for the comparison. Results The tensile test happens to be an essential one for engineers due to the fact that most important properties can be obtained from in it. These important properties include properties such as the yield stress or the elastic limit, the ultimate tensile stress, the young’s modulus, the percentage elongation, the proof stress as well as the percentage reduction in area at fracture. These are quite important properties to engineers hence giving this test a great value. Each and every detail of the tensile test is in one way or another related to the internalized changes that are produced within the metallic material by stress if under the assumption that the machine carrying out the test is accurate in each and every way. Most of the above mentioned properties can be determined through analysis of the curve that has been created by the stress () against the strain () graph. The region of deformation happens to one among the most significant pieces of information from the curve that is created by the stress () against the strain () graph. This shows out the stress which the metal goes through during the experiment. The range of elasticity happens to be a reversible deformation where inter atomic bonds are stretched in line of the stress applied. The metal has the chance to return to its original dimensions should the stress be removed. This means that the metal does obey Hooke’s law. The number that is obtained through finding the slope within the elastic range happens to be a constant of proportionality, which is called the Young’s Modulus of Elasticity. A point at which plastic deformation begins is known as the Yield Point. At the yield point, all deformation is always permanent. Plastic deformation has two stages. One is the uniform deformation and the other one is the necking. This brings about permanent deformation as well as showing that the slipping between two atoms has begun. The metal will be hardened by the work. This will allow that more stress will be added and is also marked by a gradient curve on the strain () against stress curve (). In this curve, the highest point will mark the ultimate tensile strength. This point will as well mark the point at which necking will begin. This is where deformation will become localized and a small constriction is able to be seen where the deformation occurs. Ductility is what will measure the degree of plastic deformation, which is sustained at fracture. A material is described to be brittle at a time it experiences very little up to zero plastic deformation. The data collected and used for calculation of tensile properties for both aluminium and copper metals. Fort the two metals, properties calculated are used to calculate to determine the ultimate tensile strength, true stress at fracture, breaking stress, percentage of elongation and the percentage area reduction after reduction. For copper, the tensile strength calculated was 319.40Mpa, the breaking stress calculated to 198.04 Analysis and Discussion The elastic as well as the plastic deformation region for the aluminum and the copper materials got to be identified in the graphs, which were obtained from the first part. According to the observations from the graphs, it is true that the elastic region of the aluminum material is larger than that one of the copper metal. This outcome fails to agree with the general theoretical knowledge that aluminium is softer compared to copper. There is a likely hood that this might have been caused by the unfamiliarity with the equipment used in the test. Therefore, the elastic range of aluminium is much higher than that of copper due to the fact that it is more brittle than copper. Aluminium is a much softer material compared to copper. Aluminium also has a lower ductility than that one of the copper. In theory, copper metal has a higher tensile strength as well as yield strength compared to aluminum. Most of the results that were obtained from the lab experiment failed to be accurate when compared to those results that are published. A good example for that can be seen in the young’s modulus for copper, which had been calculated to be 156.0GPa, and had a difference of 41.8 percent from the published value, which is 110GPa (Callister, 2007). This disparity could have resulted due to the inaccuracy of the extensometer or even the difficulties, which were experienced in the usage of the extensometer in the experiment. It proved to be very hard to obtain an accurate reading. The slightest change in the position or the hold of the sample caused a change in the reading. The fracture surface of the copper made almost an identical rim on the both ends of the material. Another thing is that the necking on the copper material specimen appeared to be less severe. On the other side, the fracture on the aluminium material did not appear as clean as that one of the copper. The reason to this is that aluminium is a softer material than copper and that allows it to withstand more deformation before it fractures. At the time of elastic deformation, there happens to be a stretch between atomic metal bonds. This fact brings about deformation within the metal at a time when stress is applied. However, the type of deformation experienced by the metal here is not permanent. To put it in another way, after the load has been removed, the part that was experiencing the deformation returns back to its original shape as well as dimensions. For that reason, deformations experienced in this region are said to be reversible. At the time of plastic deformation, the atoms that are moving relative to each other cause slip and bonds are Brocken. Due to the fact that bonds are broken causes deformation within this region to be permanent. This means that once the load is removed, the part that was facing deformation will not return to its original shape and dimensions, but will retain shape that was caused by the deformation. The yield structure of a certain metal would be very crucial particularly during the selection of material for building up a structure. This is due the fact that the material in a certain structure cannot exceed its yield point. In a case where it does exceed its yield point, it will enter the plastic range and this is where deformation is permanent. This experience will subsequently lead to the building growing weaker subsequently. The major aspect that should be taken into consideration as far as this is concerned is the principle of safety. This principle should be of uttermost importance to an engineer. Conclusion This lab experiment did explore the tensile properties of aluminium and copper. For both the aluminium and the copper, the change through each metals region of deformation was observed. The extension of load graph for the aluminium and the copper was also obtained. Another thing is that the percentage of elongation as well as the percentage of reduction of the area at breaking was calculated. The outcome showed that copper was harder as well as more ductile compared to aluminium. In the second part of the laboratory experiment, the slope of the stress against the strain curve that was obtained from the data, which had been gathered from the readings of the extensometer, was used to calculate the Young’s modulus of Elasticity. These readings joined with the stress readings from the extensometer, enabled for strain and stress to be computed at the time of elastic deformation for steel and brass. Reference Callister , D.W. (2007) Materials Science and Engineering an Introduction 7th Ed. York: John Wiley & Sons Inc. Read More