The Jominy End-Quench Experiment to Understand Various Aspects and Process in the Metal Structural Industry - Lab Report Example

JОMINY ЕND-QUЕNСH LАB RЕРОRT Name Professor Institution Course Date Introduction The Jominy end-quench test is very useful in determination of steel hardenability. This is associated with the capability of steel to undergo a partial or complete transformation from austenite to a portion of martensite at a particular depth under the surface. This takes place during the cooling process under high temperature conditions. The heat treatment for quench and temper utilises the transformation of the cooling phase to bring about hardening in steels. The steel hardenability refers to the feature that leads to the determination of the distribution and depth of hardness and the depth resulting from quenching through the austenitic condition. The transformation feature for time-temperature of steel is important in understanding the manner in which hardness depends upon the rate of quenching (Rajan and Sharma, 2012). The process of quenching using oil, water or any other suitable medium may bring about hardening of a part. Rapid cooling of such parts may result in high levels of hardness. However, the rate of cooling for the interior parts is low and this leads to the prevention of hardening. The nature of temperature time diagram for steel prevents a linear variation of hardness from the external parts to the centre. The hardenability suggests the occurrence of the depth of hardening as opposed the maximum hardness that can be attained. For steel, the hardenability is dependent on three factors, which include its composition, austenitic size of grain as well its structure prior to quenching. Generally, the presence or increase of carbon as well as other alloys are responsible for the increase in hardenability for steel (Alavudeen and Jappes, 2006). Purpose The purpose of the Jominy end-quench test was to realize the exploration of the relationship that exists between the composition and hardenability of various forms of steel. Aim The aim of the Jominy end-quench test was to identify and confirm the achievement correct hardenability in accordance with what is already stated or in record as the current hardenability data for steel. Apparatus Heat treatment furnace, Lathe machine, quenching fixture with flow of water, steel ruler and calliper, Rockwell C hardness tester, safety cloths and equipment as needed Procedure 1. Three different samples of Jominy were obtained; on of which had a content of plain carbon steel and the others consisted of different steel alloys. Each one of the samples used in this test was cylindrical in shape with dimensions as Diameter of 1” (25.4 mm) and a length of 4” (101.6 mm). The illustration of the specimen used is as shown below. 2. All of the samples were then austenitized by subjecting to the heat in the furnace where they were heated up to temperatures of between 850 oC and 900 oCfor at least 20 minutes. 3. The first sample was then taken out of the furnace and immediately dropped into a fixture meant for quenching with controlled flow of water at 24 oC. The sample was held within the fixture for a period of 10 minutes while making sure that the water flow touched the entire face at the bottom of the sample. Care was also taken to prevent the splashing of water on the sides of the samples. After that, the sample was dropped into a tank of water to cool it down. 4. The decarburised material of the sample was removed by flat grinding the sample along its length down to a depth of 0.38 mm (0.015”). Care was taken not to overheat the sample. 5. The Rockwell C hardness was measured starting from the quenched end of the sample for the first length of 50.8 mm (2”). This was continued at a typical interval of 1.6 mm (1/6”) for the initial 12.7 mm (1/2”) and 3.2 mm (1/8”) for the portion of 38.1 mm (1.5”). This was done while paying particular attention to the initial three readings. 6. The above steps from (2) to (5) were repeated for the other samples. Results and Discussion Sample No: 819 Distance from the quenched end Hardness (HRC) Expected Microstructure Justification 0 mm 50.6 martensite The specimen undergoes rapid quenching in the flow of cold water. It acquires the hardest microstructure in comparison to various microstructures of steel alloy. The rapid quenching also brings about brittleness. 1.6 mm 50.6 3.2 mm 48.9 4.3 mm 35.8 6.4 mm 27.6 8.0 mm 26.2 9.6 mm 21.5 11.2 mm 24.7 12.8 mm 25.1 16.0 mm 23.5 19.2 mm 19.1 22.9 mm 20.5 25.6 mm 20.2 28.8 mm 19.0 32.0 mm 16.3 35.2 mm 16.2 38.4 mm 16.6 44.6 mm 16.2 44.8 mm 15.2 48.0 mm 13.1 51.2 mm 13.8 54.4 mm 9.9 Tabulated results for steel sample: 819 Sample No: 748 Distance from the quenched end Hardness (HRC) Expected Microstructure Justification 0 mm 38.8 Course pearlite The process of annealing relieves the stresses, which in turn causes an increase in ductility and the modification of the microstructure. The annealing process comprises of recrystallization recovery as well as grain growth. The conduction of the quenching process follows the formation of grain in order to achieve the facilitation fine-grained microstructure production 1.6 mm 36.2 3.2 mm 38.8 4.3 mm 39.3 6.4 mm 19.3 8.0 mm 42.0 9.6 mm 30.6 11.2 mm 23.6 12.8 mm 28.2 16.0 mm 30.4 19.2 mm 29.5 22.9 mm 30.1 25.6 mm 30.4 28.8 mm 29.0 32.0 mm 29.8 35.2 mm 32.4 38.4 mm 31.6 44.6 mm 30.4 44.8 mm 31.3 48.0 mm 31.2 51.2 mm 30.5 54.4 mm 30.5 Tabulated results for steel sample: 748 Sample No: 930 Distance from the quenched end Hardness (HRC) Expected Microstructure Justification 0 mm 53.1 Fine pearlite When the specimen is austenized the allowed to undergo cooling in air, it experiences the normalizing process. The application of this process takes place in order to brittle effects brought about through cold working. The heating of the sample within the range of austenite allows recrystallization and the relative refinement of the grains structure. 1.6 mm 39.4 3.2 mm 48.9 4.3 mm 49.3 6.4 mm 49.2 8.0 mm 48.5 9.6 mm 49.6 11.2 mm 48.3 12.8 mm 49.2 16.0 mm 49.2 19.2 mm 49.7 22.9 mm 35.5 25.6 mm 45.2 28.8 mm 45.6 32.0 mm 45.3 35.2 mm 45.3 38.4 mm 45.2 44.6 mm 49.6 44.8 mm 53.1 48.0 mm 51.9 51.2 mm 49.8 54.4 mm 48.0 Tabulated for steel sample: 930 Graphical representation of steel samples tested Hardenability in steel is important because it offers a fundamental description of the depth to which the hardening of steel is expected to take place during the process of quenching. It also indicates the property of steel with regard to its grain size as well as chemical composition. Typical applications of the steel samples tested include manufacture of automobile bodies, bridges, structural shapes as well as pipelines for low carbon steels. Manufacture of machine parts, gears and railway tracks for medium carbon steel and production drills, cutting tools as well as surgical tools for high alloy steels (Rajan and Sharma, 2012). A comparison of the effectiveness of quenching done in oil and moderately agitated water for 75 mm (3 inch) diameter of 8640 steel indicates that for water that is moderately agitated, the hardness and equivalent distances show variations as tabulated below: Radial position Equivalent distance Hardness HRC Surface 4 57 0.75 radius 9 52 0.5 radius 13 48 Centre 18 43 Effectiveness of quenching for moderately agitated water Radial position Equivalent distance Hardness HRC Surface 12 48 0.75 radius 18 42.5 0.5 radius 21 38 Centre 26 37 Effectiveness of quenching for moderately agitated oil The plot of the above data indicates: Conclusion 1 In conclusion, the performance of the Jominy end-quench experiments allows us to obtain an understanding of the process such as heat treatment in steel and other manufacturing operation and process. The experiment is also important to providing a better understanding the tools and equipment that are used in examination hardness in various types of steel and other metals. The experiment has also played a major role in equipping the participants with a wider knowledge and understanding in various variations that are present in the microstructures of various types of metals. The experiment allowed the participant to become well conversant with the requirements and the necessary procedures in performing Jominy end-quench experiments. It is very useful to determine the hardness and microstructure of a given metal before it can actually be utilised in any given project. This is the knowledge and understanding that is brought about by performing and participating in the Jominy end-quench experimental test (Rajan and Sharma, 2012). Conclusion 2 The Jominy end-quench experiment brings a wide and clear understanding with regard to various aspects and process in the metal structural industry. By taking part in the experiment or performing the experiment, the participants are in a better position to equip themselves with structural aspects that occur in steel metal s such as hardenability as well as its significant. The experiment also offers an opportunity to study a variety of microstructures that form part of several metals and their typical applications. It is through carrying out this particular experiment that the participants are presented with rare opportunity to interact very closely with various tools and equipment that performs several experimental and testing functions. This experiment offered an opportunity for those who participated to implement and prove the theoretical knowledge they have already learnt into actual practical cases. The practical understanding of aspects if very resourceful since it clarifies some of the issues that cannot be theoretically clarified (Alavudeen and Jappes, 2006). References Alavudeen, A & Jappes, J. T. W. (2006). A textbook of engineering materials and metallurgy. New Delhi: Laxmi Publications. Rajan, T. V. & Sharma, A. (2012). Heat treatment: principles and techniques. New Delhi, PHI Learning. Read More