Wear Resistance of Basic Engineering Materials - Assignment Example

Materials Unit 21 assignment Qualification Unit number and BTEC Level 4 HNC Engineering Materials Unit 21 Materials Engineering 2188C name Assessor name Edward Strickland Date issued Completion date Submitted on 22/5/2015 5/6/2015 Assignment title Materials Engineering. This assignment represents 100% of the total assessment for this module. This unit will provide learners with the necessary background knowledge and understanding of the properties, selection, processing and failure of engineering materials. Links Successful completion of Unit 8: Engineering Design and this unit would enable learners to meet, in part, the Engineering Technician (Eng Tech) and Incorporated Engineer (IEng) requirements laid down in the UK Engineering Council Standard for Professional Engineering Competence (UK-SPEC) Competence B2, ‘Identify, organise and use resources effectively to complete tasks, with consideration for cost, quality, safety and environmental impact’. Essential requirements Learner access to suitable materials testing equipment, specimens and test instrumentation is required. The range of tests chosen will depend on the learner’s working environment and particular needs but will need to include, as a minimum, tests that involve metals and polymers. Sample materials from each of the four categories for inspection, as well as products/structures produced from these categories of material, are also required. Employer engagement and vocational contexts Liaison with employers would prove of benefit to centres, especially if they are able to offer help with the provision of a suitable materials testing and/or processing/fabrication environment. LO Learning outcome (LO) AC In this assessment you will have the opportunity to present evidence that shows you are able to: Task no. Evidence (Page no) LO1 Be able to determine the properties and selection criteria of materials from test and data sources 1.1 Detail the appropriate material properties and criteria for the selection of a metallic, ceramic, polymer and composite 1.2 Explain the particular characteristics related to the microstructure and macroscopic behaviour of the four categories of engineering materials 1.3 Generate and process test data to assess material properties for two categories of material 1.4 Investigate and assess the quality of suitable data from three different sources LO2 Understand the relationships between manufacturing process and material behaviour 2.1 Explain how one heat treatment process and two other treatment processes affect the structure, properties and behaviour of the parent material 2.2 Explain how one liquid processing method and two mechanical processing methods affect the structure, properties and behaviour of the parent material 2.3 Investigate how the composition and structure of metal alloys, polymers and polymer matrix composites influence the properties of the parent material LO3 Be able to select suitable materials and processing method for a specific product 3.1 Analyse the function/s of a product in terms of the materials’ constraints on its design 3.2 Identify the required properties for the product and select the most appropriate materials and processing methods 3.3 Identify and explain the possible limitations on the product imposed by the processing and by the need to safeguard the environment and minimise costs LO4 Understand the in-service causes of failure of engineering materials 4.1 Explain the common causes of in-service failure for products or structures produced from each or a combination of the four categories of engineering materials 4.2 For one product or material structure, identify and explain the in-service conditions that may contribute to early failure 4.3 Explain the methods for investigating materials failure and for estimating product service life, when a product is subject to creep and fatigue loading 4.4 Determine and make recommendations for remedial/preventive measures for a given product or Materials structure, that will help improve its service life. Learner declaration I certify that the work submitted for this assignment is my own and research sources are fully acknowledged. Student signature: Date: In addition to the above PASS criteria, this assignment gives you the opportunity to submit evidence in order to achieve the following MERIT and DISTINCTION grades Grade Descriptor Indicative characteristic/s Contextualisation M1 Identify and apply strategies to find appropriate solutions Effective judgements have been made. An effective approach to study and research has been applied. Consideration has been given to the six methods of NDT. Reasoned judgements are made about the factors affecting the most suitable NDT method. Strategies have been applied to find the appropriate solution. (Task 3) M2 Select/design and apply appropriate methods/techniques Complex information/data has been synthesised and processed. Appropriate learning methods/techniques have been applied. Complex information has been used to determine the five forms of steel. The data has been used correctly to obtain an accurate description of properties. Appropriate method and technique has been demonstrated. (Task 4) M3 Present and communicate appropriate findings The appropriate structure and approach has been used. The communication is appropriate for unfamiliar audiences and appropriate media have been used. The slides prepared have appropriate structure and approach to show how different steels perform in comparison to each other. The materials prepared present and communicate the approach to use which a third party, with limited materials knowledge, would be able to follow. (Task 4) D1 Use critical reflection to evaluate own work and justify valid conclusions Conclusions have been arrived at through synthesis of ideas and have been justified. The validity of results have been evaluated using defined criteria. The information given in the task has been used in an analytical manner to evaluate the answers arrived at by graphical/drawing means (Elastic and Plastic chart of stress vs strain). The results compared are validated. Links and comparisons are made between drawing and analytical solutions. (Task 1) Students should evaluate a sample of material performance critically. D2 Take responsibility for managing and organising activities Activities have been planned. Autonomy has been demonstrated. The use of a material to provide functionality which is realistic. The assignment is completed on time. Autonomy has been demonstrated and deadlines met independently. (Task 5) D3 Demonstrate convergent/lateral/creative thinking Ideas have been generated and decisions taken. Problems have been solved. Creative thought has been applied. The decision on two material surface processes is valid and the explanation shows a range of ideas to support this choice of different material surface properties. The explanation will clearly show creative ideas about minimising corrosion. (Task 5) Please note that for unit assignments Assessors should use these or other exemplar indicative characteristics for the individual grade descriptors from Annexe C of the HN specification or any other relevant indicative characteristics for the particular assignment. The indicative characteristic should then be contextualised. Only one indicative characteristic per grade descriptor, M2, M2, M3, D1, D2, D3 is required. Assignment brief Unit number and title Unit 21 Materials Qualification Pearson BTEC Level 5 HND Mechanical Engineering Start date 22/5/2015 Deadline/hand-in 5/6/2015 Assessor Assignment title Materials Unit 21 assignment Purpose of this assignment This assignment will give you the opportunity to show your knowledge of basic engineering problems involving the strength of materials. The selection of the most appropriate materials for an engineered product and their processing is of prime importance if the product is to be fit for purpose. Engineers must thus be aware of the range of materials at their disposal. Knowledge of the structure of materials and the way in which this affects their properties is also desirable. Material properties may be determined or verified by testing and engineers should be aware of the range of standard tests and test equipment that is used and be able to interpret the test data. Materials generally need to be formed to shape, fabricated or processed in some other way, to make engineering components. The properties of the raw material can affect the choice of process and in some cases the choice of process can affect the final properties of a component. Materials also, for a variety of reasons, sometimes fail in service and engineers need to be aware of the modes and causes of such failure, as well as the preventative methods that may be used, to prolong their service life. This unit will thus provide learners with the necessary background knowledge and understanding of the properties, testing, treatments, processing, selection, failure modes and prevention of a variety of engineering materials. In addition, this unit offers learners the opportunity to consider environmental issues related to increased productivity and sustainability that lead to less waste and to the more efficient use of energy and resources when selecting materials for particular applications. Scenario You are going to spend five months of practice as a Mechanical Engineer in “First Testing Company”, one of the biggest Machine Elements Laboratories in the United Kingdom. You will be required to attend an interview and in preparation for this your potential supervisor asks you to solve the following tasks in order to assess your level of knowledge and understanding. Task 1 : (LO 1: 1.1, 1.2, 1.3,1.4 and D1) Research 1: For the diagram below define the terms 1. Proportional limit This is the strain below which the stress of the material is proportional to strain. 2. Yield stress This is the stress level at which the material stops beings elastic. 3. Ultimate stress This is the maximum stress that a material can withstand while being stretched before breaking. 4. Fracture Breaking of a material when subjected to external stress. And explain what is happening in the following regions. 1. Elastic region In this region, the material is able to return to its un-deformed state when all the forces applied on it are removed. 2. Yielding region In this region, the material is stretched beyond its limit and when the applied force is removed, the material cannot go back to its original state. 3. Strain hardening region In this region, the material is strained beyond the strain yield limit and therefore additional stress is required to produce additional plastic deformation on the material. 4. Necking region In this region, the cross section of the material reduces by a greater proportion as compared to the hardening of the material. This results in instability of the material during tensile deformation. Task Graph in Excel, as above, the relevant data for the selection of a metallic, ceramic, polymer and composite. 1.1 Detail on graph the appropriate material properties and criteria for the selection of a metallic, ceramic, polymer and composite. Graph 1: stress versus strain in metals Graph 2: stress versus strain in polymers Graph 3: stress versus strain in ceramics Graph 4: stress versus strain in composites 1.2 Explain on graph the particular characteristics related to the microstructure and macroscopic behaviour of the four Categories of engineering materials (metallic, ceramic, polymer and composite). Metallic a) They are malleable b) They undergo fracturing when subjected to high levels of stress and strain c) Metals usually undergo either plastic or elastic deformation d) They have a high yield strength and modulus of elasticity Ceramic Low ductility They have a high modulus of elasticity They have a high level of hardness Polymers a) They have a low modulus of elasticity b) They have a low strength c) They have a high elongation to break Composites d) They have a high modulus of elasticity e) They have high strength f) They have a low elongation to break 1.2 Generate and process test data (on graph) to assess material properties for two categories of material 1.4 Investigate and assess the quality of suitable data from three different sources Table 1: Data set 1 Polymer strain stress 0 0 1 0.17 3 0.19 4 0.20 Ceramics strain strain 0 0 1 0.17 3 0.19 4 0.17 5 0.19 Table 2: : Data set 2 Polymer strain stress 0 0 1.5 0.21 2.5 0.27 3 0.32 Ceramics strain strain 0 0 1.5 0.21 2.5 0.27 3 0.32 3.5 0.27 Table 3: Dataset 3 Polymer strain stress 0 0 2.0 0.23 2.5 0.27 3.0 0.31 Ceramics strain strain 0 0.2 2.0 0.23 2.3 0.27 3.7 0.36 Dataset #1 is the best representation of the mechanical properties of the two categories of materials. Their curves show the most appropriate behaviour. Task 2 (LO 2) Research 2: For the Brinell hardness testing find and record:- 1. The advantages. a) Almost all the metals can be tested in the Brinell hardness tests. b) The Brinell tests use a sphere instead of a point r a cone and therefore a wider sample of materials can be tested. c) Suitable for testing even under rough conditions d) The test procedure is simple e) Conversion into tensile strength for various metals f) It is suitable for test on inhomogeneous materials g) The results from the Brinell tests are independent of force. 2. The limitations. a) Restriction of application range to a maximum of Brinell hardness of 650 HBW b) Restriction when testing small and thin walled specimen c) Restriction when testing round specimen when the diameter is smaller than 1.5 x penetrator diameter d) Relatively serious damage to specimen as a result of large indentations 2.1 Explain how one heat treatment process and two other treatment processes affect the structure, properties and behaviour of the parent material a. Heat treatment As the temperatures increase, the ductility of the parent material also increases but this compromise the hardness and the strength of the material. The parent material becomes more brittle and tougher. In this condition, the material is in the best condition to flow and the grains of the parent materials will be distorted making the material more work hardened. b. Bulk forming process In this process, the shape of the parent material is changed by applying force on the material. The kind of change that results from this process is plastic deformation which is permanent. The mechanical properties of the parent materials can be controlled whereby the porosity and drainage of the materials can be controlled through rolling and forging. The thermo chemical properties of the materials can also be controlled. The grain structure of the parent materials can be controlled using this process. c. Powder methods In this process, the sintering process is used to make various parts of the parent materials. Through compaction, the porosity of the parent material can be altered. The products will have a higher tensile strength and elongation as compared to the parent materials. Through powder processing methods, the ductility of the parent materials can be improved. 2.2 Explain how one liquid processing method and two mechanical processing methods affect the structure, properties and behaviour of the parent material a. Liquid processing method Liquid processing methods normally affect the appearance of the parent material. The shape and the colour of the parent material can be altered. The grains and the porosity of the parent materials can also be altered through liquid processing methods thus leading to a change in the structure of the parent materials. The parent materials become less ductile through liquid methods of processing thus reducing their toughness and tensile strength. b. Mechanical processing methods The mechanical processing methods normally affect the shape and elongation of the parent materials. The tensile strength and the ductility of the parent materials are increased and the materials become harder. Through mechanical processes such as compaction and machining, the grains of the parent materials can be brought closer together thus making the materials more ductile and harder. 2.3 Investigate how the composition and structure of metal alloys, polymers and polymer matrix composites influence the properties of the parent material Increasing the content of the metal alloys in the parent materials normally results into the alteration of the shape of the material. This makes the polymer composites more homogenous. The compression strength of the material also increases with the increase in the content of the alloy in the parent materials. Materials with metal alloys, polymers and polymer matrix composites exhibit an improved level of strength and an elongated shape of the parent materials. The adhesion between the particles of the parent materials and the polymeric matrix may also be affected by the presence of these materials. This may ultimately alter the young’s modulus of the material thus affecting the strength of the parent materials. Task 3 (LO3 and M1) Research 3: For each of the 6 methods of NDT Visual, Liquid penetration, Magnetic, Ultrasonic, Eddy current and X-ray a. Find one additional example for each within the engineering industry, with a description of the application a. Visual This method is used in materials production to determine the quality and colour of the materials produced. b. Liquid penetration It is used in aeronautics and mechanical testing of cracks on surfaces. c. Magnetic The automotive industry to determine the performance of automobile engines. d. Ultrasonic It is used in cyclic loading where the determination of life is very crucial. e. Eddy current It is used in large industrial motors to control the running of machines f. X-ray X-rays are used in the medical field to determine the extent of damage on internal structures such as bones. g. Describe for each the reasons the particular method was used over the alternative methods a. The visual method allows the inspection of the appearance and visible quality of the materials without subjecting them to conditions that would otherwise alter their appearance or quality. b. The liquid penetration method allows for the exposure of any existing micro cracks through illumination of UV light on the liquid. This way, cracks of very minute size can be determined without subjecting the materials to stress. c. Magnetic methods allows for any defect on the materials to be detected using electromagnetic radiations by not altering the structure and appearance of the materials. d. Ultrasonic method is used over sonar because it is the waves that create the image during testing unlike the sonar method which uses vibration. The method can be used at high temperatures and for the determination of the crack size and damage on surface. e. Eddy currents are used over other methods because they allow for any defect on the materials to be detected using electromagnetic radiations by not altering the structure and appearance of the materials. f. X rays are used over other methods since they allows for any defects to be detected and also determine the quality of the materials. Micro cracks can easily be detected in materials unlike in the other methods. 3.1 Analyse the functions of a product in terms of the materials’ constraints on its design a) Transformation from one form to another. In this regard, one must take into consideration the materials constraints that exist which include compression, torsion, tension, deflection and shearing. b) The products are also used to characterise the properties of the materials. This involves the determination of the mechanical properties of the materials such as resilience, elasticity, ductility, malleability, stiffness and hardness. c) Linking the different products of the materials. Linking can occur in a number of forms including: direct or indirect, rigid or flexible, removable or no-removable and complete and non complete linkages. 3.2 Identify the required properties for the product and select the most appropriate materials and processing Methods a) Electrical conductivity b) Thermal conductivity c) Hardness d) Toughness e) Cost f) Resistance to corrosion The most appropriate materials and processing Methods are: a) Electrochemical machining b) Laser processing method 3.3 Identify and explain the possible limitations on the product imposed by the processing and by the need to safeguard the environment and minimise costs a) A higher amount of force and energy is required to process the materials as compared to the other methods of processing. b) Other than the forging process, all the other processes produce materials of uniform cross section area. c) Materials that have cross holes in them cannot be produced using these methods. d) The waste materials produced in these processes is hazardous and very harmful if released to the environment. Therefore, there is needed to come up with a strategy and method of disposal of the waste products. e) The cost of production of the products is quite high and therefore there is need to come up with a strategic way to process the materials at a cost effective approach. Task 4 (LO 4, M2 and M3) Research 4: For the five forms of steel Martensitic, Austenite, Cementite, Perlite Course and Perlite fine, Discuss a. How each is formed and the requirements for their formation 1. Martensitic Martensitic is formed through rapid quenching of austenite to room temperature. The requirement for the formation of Martensitic are: A high concentration of carbon, presence of a concentration of alloys, transformation of the temperatures and presence of a high strain rate austenite. 2. Austenite Austenite is formed in two main ways. The first way is through the dissolution of pearlite and the second process is through the transformation of ferrites to Austenite. The requirements for the formation of Austenite are: High temperatures 7230C-15000C, high strain rate ferrite and low carbon concentrations. 3. Cementite Cementite is normally formed through the melting of white cast iron whereby it is precipitated out of the iron as a carbon component to form large particles. The requirements for the formation of cementite are: Temperatures of 408 k, presence of white cast iron and low carbon concentrations. 4. Perlite Course Perlite Course is normally formed through rapid cooling of alloys of iron. This normally begins at temperatures of 7230C-15000C and this is dependent on the composition of the iron alloy. The requirements for the formation of Perlite Course are: High temperatures 7230C-15000C, rapid variations in the temperatures and low carbon concentrations in the alloys. 5. Perlite fine Perlite fine is normally formed through slow cooling of alloys of iron. This normally begins at temperatures of 7230C-15000C and this is also dependent on the composition of the iron alloy. The requirements for the formation of Perlite Course are: High temperatures 7230C-15000C, low variations in the temperatures and low carbon concentrations in the alloys. b. The different properties of each. E.g. Hardness, toughness etc. 1. Martensitic a) It has a high level of malleability b) Have high level of toughness and resistant to fracture c) High level of durability as compared to other forms of steel. 2. Austenite d) It has a high level of malleability e) The ductility increases with increase in temperatures f) Have high strength and resistance to fracture g) Long lasting and resistant to wear. 3. Cementite a) Plastic deformability increases with increase in temperatures. b) It is brittle at temperatures below 373 K. c) It has a low strain rate at high temperatures 4. Perlite Course a) The size of grain is basically large b) The material has a rough texture c) Low amounts of strength as compared to perlite fine 5. Perlite fine a) The size of grains is smaller as compared to perlite course b) The material has a smooth texture c) Higher amounts of strength as compared to perlite course Task 5 (LO 4 and D2) Research 5: You have been approached by a manufacturer of an Aircraft Undercarriage and asked to design a new Retracting Lever for their new model. (see image below) For both of these components: a. Give an example of the material that could be used to make them. Steel b. The properties that the materials require to perform their function safely and efficiently. a) Modulus of elasticity E = 210,000 N/mm² b) Shear modulus of 81,000 N/mm² c) Yield strength greater than  355 N/mm² d) High level of toughness and ductility c. Describe any treatments that the materials may need. i.e. hardening etc. and how this can be performed. 1. Hardening In this process, the steel is heated at a temperature beyond the critical point. It is then held at this temperatures and then quenched/cooled using oil, brine or water. Quenching reduces the hardness of the hardness of the steel. This is done at temperatures 3000C-5000C. This allows the material to develop a residual stress that allows the material to remain tough and resistant to fracture. 2. Tempering In this process, the steel in reheated and this leads to precipitation and spheroidisation of the carbides used in this process. The temperatures set for the tempering process must be controlled in order to monitor the properties of the required steel. The resulting benefits of this process are that it leads to the increase in the toughness and elongation of the steel. d. Describe a process by which the body of the part can be formed. 1. Heat treatment process This process involves the treatment of steel at about 4000C above its critical limit. The steel is then held at this particular temperature for a given period of time before being cooled in the presence of a cool stream of air. This stream of air must be maintained for a period of at least 2 minutes. The structure that results from this process is pearlite or cementite. This process can further be normalised to refine the grains and also provide moderate hardening of the steel. e. Describe 2 different surface processes that could be used on the retracting level to protect it from corrosion. 1. Surface lubrication This process allows the application of a lubricating coat that acts as a preventive layer against air and water. The oily layer does not allow the reactants to come into contact hence protecting the surface. 2. Daily draining of fuel sumps This prevents the fuels from seeping onto the surfaces thus preventing any form of corrosive reactions occurring on the surface. 4.1 Explain the common causes of in-service failure for products or structures produced from each or a combination of the four categories of engineering materials. Try to predict what would happen if you redesigned the lever with either each or a combination of the categories of material. a. Design errors Components such as undercuts can result into in-service failure for different products or structures thus reducing their life span. b. Poor selection of materials Materials that are corrosive undercuts can result into in-service failure for different products or structures thus reducing their life span. c. Defects in the selected materials Slag selection in materials increase the stress and this also may reduce the in-service failure for different products. d. Errors in the assembly of the materials Errors such over tightening of the screws may cause unnecessary stress on the materials thus affecting the in-service life of the structures. e. Poor service conditions This involves proper treatment of the structures and the materials thus affecting the in service life of the product. The temperatures and corrosion must be monitored in order to increase the in service of the product. f. Overloading Using the products to lift loads that are beyond the set limits may also affect in service life of the product. g. Abuse This is the use of the products for purposes other than the intended purposes. This reduces the in-service of the products. 4.2 For the retracting lever, identify and explain the in-service conditions that may contribute to early failure. The conditions that can lead to early failure in the retracting lever are: a. Design errors which may cause unnecessary fractures and cracks on the lever thus resulting in early failure. b. Poor selection of materials may result in unnecessary corrosion of the materials thus causing early failure of the materials. c. Poor service conditions may cause early failures from corrosion, overheating and tear and wear resulting from poor maintenance of the retracting lever. 4.3 Explain the methods for investigating materials failure and for estimating product service life, when a retracting lever is subject to creep and fatigue loading a. The factor method This method takes into consideration three important factors in the investigation of the failure of materials and also estimating the product life service. The factors taken into consideration are: The required design life, the reference service life and the modifying factors. This method goes further beyond investigation of the failure of materials and also estimating the product life service and determines the cost of the product. b. Reliability analysis method This method makes use of probabilistic methods to investigate of the failure of materials and also estimating the product life service. This method determines the time to failure and the time between failures. To achieve this, the analysis must take into consideration the survival data, the event time data and the degradation data. 4.4 Determine and make recommendations for remedial/preventive measures for a retracting lever that will help improve its service life. a. Automatic operation The retracting lever should be automatically operated in order to ensure that the movable parts come into minimal contact with external interference. This will ensure that the retracting lever operates for a longer in service of the product. b. Frequent lubrication The retracting lever should also be lubricated regularly in order to prevent corrosion, tear and wear. This way, the retracting lever can have its in service life improved by a considerable magnitude. Evidence checklist Summary of evidence required by student Evidence presented Tasks 1, 2, 3, 4 and 5 A report written in a formal style, including a contents page indicating the different report chapters and sections. Attach your Assignment 1 report and witness statement to your results for Task 1 to 5. This must be submitted electronically A bibliography with references must be supplied using the Harvard System of referencing. An electronic copy of your reports submitted electronically on moodle. Achievement Summary Qualification Pearson BTEC HND Diploma in Mechanical Engineering Assessor name Ed Strickland Unit Number and title Unit 21 Materials Student name Criteria Reference To achieve the criteria the evidence must show that the student is able to: Achieved? (tick) LO 1 Be able to determine the properties and selection criteria of materials from test and data sources LO 2 Understand the relationships between manufacturing process and material behaviour LO 3 Be able to select suitable materials and processing method for a specific product LO 4 Understand the in-service causes of failure of engineering materials Higher Grade achievements (where applicable) Grade descriptor Achieved? (tick) Grade descriptor Achieved? (tick) M1: Identify and apply strategies to find appropriate solutions D1: Use critical reflection to evaluate own work and justify valid conclusions M2: Select / design and apply appropriate methods / techniques D2: Take responsibility for managing and organising activities M3: Present and communicate appropriate findings D3: Demonstrate convergent/lateral/creative thinking Assignment Feedback Formative Feedback: Assessor to Student Action Plan Summative feedback Feedback: Student to Assessor Assessor signature Date Student signature Date Read More