Fabrication and cold upsetting behaviour of al-5.4zn alloy/coal ash/sic particles reinforced composites

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The study was intended to evaluate the effect of reinforcement percentage on the deformation behaviour. The mechanical properties like hardness, tensile behavior, modulus of elasticity, yield stress have been carried out.

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Nội dung Text: Fabrication and cold upsetting behaviour of al-5.4zn alloy/coal ash/sic particles reinforced composites

International Journal of Mechanical Engineering and Technology (IJMET) Volume 10, Issue 03, March 2019, pp. 298-303. Article ID: IJMET_10_03_031 Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=3 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 © IAEME Publication Scopus Indexed FABRICATION AND COLD UPSETTING BEHAVIOUR OF AL-5.4ZN ALLOY/COAL ASH/SIC PARTICLES REINFORCED COMPOSITES Ramesh Jami Research Scholar, Dept of Mechanical Engineering, Acharya Nagarjuna University M. Gopi Krishna Assistant Professor, Dept of Mechanical Engineering, Acharya Nagarjuna University ABSTRACT Experiments on cold deformation behaviour are conceded out on as cast and homogenized Al-5.4Zn /coal ash/ Silicon carbide composite billets. The study was intended to evaluate the effect of reinforcement percentage on the deformation behaviour. The mechanical properties like hardness, tensile behavior, modulus of elasticity, yield stress have been carried out. The microstructures were taken from SEM to examine the distribution of ash and SiC particulates in the matrix. The deformation process is carried out between two flat platens and sample at the center to envisage the metal flow at room temperature. To observe the changes in hardness after deformation the hardness measurements were carried out to examine the changes after the forging. It is observed from the experimentation that the circumferential stress σθ has positive values (tensile) with unremitting deformation. As the barreling initiates, the axial stress, σz will get compressive values. The effect of strength coefficient and strain hardening behaviour with the sample deformation and barreling effects have been calculated. Key words: Friction, cold upsetting, coal ash, strain hardening behavior Cite this Article Ramesh Jami and M.Gopi Krishna, Fabrication and Cold Upsetting Behaviour of Al-5.4zn Alloy/Coal Ash/Sic Particles Reinforced Composites, International Journal of Mechanical Engineering and Technology, 10(3), 2019, pp. 298-303. http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=3 http://www.iaeme.com/IJMET/index.asp 298 editor@iaeme.com
Fabrication and Cold Upsetting Behaviour of Al-5.4zn Alloy/Coal Ash/Sic Particles Reinforced Composites 1. INTRODUCTION Lightweight materials are suitable for advanced aerospace and automobile industries. Aluminium Metal Matrix composites (AMMCs) are used to fulfill the needs of the industries which can be customized throughout the addition of preferred reinforcements to enhance the mechanical properties [1, 2]. Due to the high specific stiffness and strength at room or high temperatures the particle reinforced metal matrix composites are used. Normally micron sized ceramic particles are used as reinforcement to improve the properties of the MMCs. Flyash is the most l o w d e n s i t y a n d economical reinforcement obtainable in bulk quantities as waste byproduct after incineration of coal in power plants. Chawla et al. [3] studied the characterization and SEM examination of SiC as reinforcement in metal matrix composites which are fabricated by secondary processing methods like extrusion and identified higher strain to failure values for the extruded material also sinter forged test showed the higher value of elastic modulus and Ultimate tensile strength because of failure in particle due to fracture. The lower strains were observed for inferior bonding among the matrix and reinforcing particles when compared to deform one. V. Sethi [4] reported that incorporating ceramic particles in A356 matrix weakens the interfacial bonding and in due course resulting in the pull-out of the SiC particle. The lattice straining in the adjacent areas of the particles will reduce the extent of plastic deformation that these areas can undergo, which will make them more vulnerable to cracking. These cracks will result in the removal of the matrix from adjoining areas of the particles, thus decreasing the strength of interfacial bond 2. MATERIALS AND METHODS 2.1. Matrix alloy In the present research Al-5.4Zn alloy is chosen as matrix which is prepared in the laboratory. 2.2. Composite fabrication Investigation on aluminium based hybrid metal matrix composites is carried out with 5, 10 and 15wt% SiC and coal ash particulates of 53µm were effectively casted by eddy method. Al-5.4Zn alloy is used as matrix alloy. The fabrication is carried out using vortex (stir casting) method. Al-5.4Zn alloy is melted in a graphite crucible which is placed inside a muffle furnace. Once the required temperature is attained i.e. (750 0C) a pool was created. The preheated particulates of SiC and coal ash at were poured into the melt. To ensure the smooth and continuous flow of the particles, a conical shaped object made of tin is used so that the particles will be added exactly in the vortex. Argon gas is to be shielded around the melt to prevent oxidation. 3. DEFORMATION TESTS Deformation tests were conceded out on specimens made in cylindrical shape for the alloy and composites with height to diameter ratio of 1.0. The samples were prepared using CNC lathe for accuracy as shown in figure 1. The ends of the specimens were chamfered to minimize the folding. In order to attain low friction between die and samples concentric grooves were made on the top flat surfaces. The prepared samples were compacted by placing them between the dies (platens) at a constant speed of 0.4mm/minute in unlubricated condition, using an advanced universal testing machine. http://www.iaeme.com/IJMET/index.asp 299 editor@iaeme.com
Ramesh Jami and M.Gopi Krishna Figure 1 Deformed samples 3.1.1. Friction and Ring Compression test In metal working processes the friction arises from sliding of the work piece in opposition to the die [5]. In the interest of clarity, friction forces are often neglected. In many real metal working processes friction is the predominant factor [5]. J.P Avery et al. [6] reported the implication of compression and the properties of materials to estimate forming boundaries up to plastic unsteadiness and rupture. Substantial consideration has been dedicated to the investigation of platen forces and distribution of pressures in upsetting, particularly for discs made in thin size [7-10]. The compression test (ring) technique was started by Kunogi [11], developed further by Cockroft and Male [12] for measuring friction beneath regular processing circumstances. Before satisfactory mathematical solution for the compression of a ring was available, a pioneering independent calibration was made by experimentation [13]. Subsequent theoretical analyses [14, 15] have made possible more accurate and less laborious calibration of the ring test by mathematical computation. Avitzur [16], conducted the first satisfactory analysis of the compression of a flat ring through an optimum upper bound mathematical solution and verified by Hawkyard and Johnson [17] using a stress analysis approach. 4. RESULT AND DISCUSSION 4.1. Microstructural analysis and EDS of alloy and composites The SEM pictures of reinforcements and hybrid composites varying with wt. percentages of 5 to 15% is shown in figure 2 (a-d), it is observed that, coal ash and SiC additions in the alloy fig (b) shows the microstructure of the matrix alloy whereas figures c and d shows the addition of the coal ash and SiC to the alloy, difference in the microstructures was noticed clearly. a b http://www.iaeme.com/IJMET/index.asp 300 editor@iaeme.com
Fabrication and Cold Upsetting Behaviour of Al-5.4zn Alloy/Coal Ash/Sic Particles Reinforced Composites c d Figure 2 (a) Scanning electron microscope of coal ash particles (b)Al-5.4Zn (c) Al-5.4Zn –5% Composite (e) SiC Particle in matrix 4.1.2: Compressive Properties of the coal ash /SiC hybrid Composites Load displacement curves for deformation properties of both the alloy and the composites were shown in figure 3. 4.1.3. Strength coefficient and Strain Hardening As the Coal ash and silicon carbide content increases, the strength coefficient, K found to be increased as depicted in figure 5 .A rise in „K‟ value was observed from 410 MPa for Al- 5.4Zn alloy to 900 MPa for 10% composite. The obtained values were at 50% deformation by cold upsetting process. http://www.iaeme.com/IJMET/index.asp 301 editor@iaeme.com
Ramesh Jami and M.Gopi Krishna % Increment Strength Coefficient (K) Strain Hardening Exponent (n) % of Reinforcement Figure 5 strength coefficient By the addition of ceramic particles in solid form, the strength of the matrix was predictable to increase due to the escalation possessions occurred in particulate reinforced composites. Also the occurrence of second phase particles in the continuous metal matrix phase the plastic properties have been modified due to localized internal stresses. Hence, presence of the hard Coal ash /SiC particles made the composites high strength subsequently increase in strain hardening exponent „n‟ values for larger Coal ash /SiC particulates content.Strain hardening exponent „n‟ is increasing with increase in reinforcements Coal ash and silicon carbide) as shown in figure 5. The strengthening occurs due to the dislocations within the structure of the material which make improvements in the plastic properties to an enormous extent. Hence, presence of the hard Coal ash /SiC particles made the composites high strength subsequently increase in strain hardening exponent „n‟ values for larger Coal ash /SiC particulates content. During metal forming the dislocation density increased by several orders of magnitude. By this, higher dislocation zones of density will appear which represent an obstruction for moving dislocations. 5. CONCLUSIONS 1. Al- 5.4Zn /Coal ash/SiC Hybrid composites were fabricated by vortex method successfully. 2. The distribution of Coal ash and silicon carbide particles are uniform throughout in the matrix phase. 3. A good interfacial bonding is observed from the SEM figures, which clearly shows that there were no discontinuities and voids in the composites. 4. For the given set of compression dies in dry condition, the friction factor „m‟ was found to be 0.37. 5. Irrespective of alloy composition the friction factor values were found to be same for a given set of dies. 6. Load requirement increased with decrease in aspect ratio for given frictional condition. 7. Strength coefficient (K) increased with increase in Coal ash /SiC particulates content for all the composites compare to Al- 5.4Zn alloy. 8. Strain hardening exponent (n) increased with in Coal ash /SiC particulates content for all the composites compare to Al- 5.4Zn alloy http://www.iaeme.com/IJMET/index.asp 302 editor@iaeme.com
Fabrication and Cold Upsetting Behaviour of Al-5.4zn Alloy/Coal Ash/Sic Particles Reinforced Composites REFERENCES [1] Everett R.K, and Arsenault, Metal Matrix Composites; Mechanisms and Properties, 1991 (Academic Press, San Diego). [2] Kocjak M.J., S.C Kahtri, Allison J.E.. Fundamentals of Metal Matrix Composites (Eds S. Suresh, A. Mortensen and A. Needleman), 1993 (Butterworth-Heinemann, Boston). [3] Saha R, Williams and Chawla N, Mechanical behavior and microstructure characterization of sinter-forged SiC particle reinforced aluminum matrix composites, Journal of light metals, 2, 2002, 215-227. [4] Varun Sethi, Effect of aging on abrasive wear resistance of silicon carbide particulate reinforced aluminum matrix composite, M.S Thesis 2007. [5] Kurt Lange; Hand book of metal forming. McGraw-Hill Book Company. [6] George. E. Dieter; Mechanical Metallurgy, McGraw-Hill Book Company, pp. 539. [7] Shaw M. C, and Avery J. P, Forming Limits, Reliability, Stress Analysis and Failure Prevention Methods in Mechanical Design, A Century 2 Publication, ASME Centennial bound; Vol:1980: pp. 297-303. [8] Siebel.E., Sathl and Eisen, DUSSELDORF, Vol.43; 1923: pp. 1295. [9] Bishop J.F.W., J. Mech. Phys. Vol.6; 1958: pp. 132. [10] Schroeder.W and D. A. Wevstrer, J. App. Mech. Vol. 16; 1949: pp. 289. [11] Van Rooten G .T, and Gackofen W.A., Int. J. Mech. Sci., Vol. 1; 1960: pp.1. [12] Daneshi G. H., and Hawkyard J. B., Int. J. Mech. Sci. Vol. 13; 1971: pp. 355. [13] Kunogi, M., Reports of the Scientific Research Institute, Tokyo, and Vol. 30; 1954: pp.63. [14] A.T Male and Cockcroft, M.G., “A Method for the Determination of the Coefficient of Friction of Metals under Conditions of Bulk Plastic Deformation,” Japan Institute of Metals, Vol.93; 1964-65: pp.38. [15] Male, A. T, Ph.D., Theses, Department of Industrial Metallurgy, University of Birmingham, England, October 1962. [16] Avitzur, B., “Forging of Hollow Disks,” Israel Journal of Technology, Vol 2, No.3; 1967: pp.295. [17] Hawkyard, J. B., and Johnson, W., “An analysis of the changes in Geometry of a Short Hallow Cylinder during Compression,” International J. of Mechanical Sciences, Vol.9; 1967: pp.163. [18] H. Kudo, and K. Aoi, Effect of compression test condition, study on cold forgebility test; part II, Journal of the JSTP,8, 1967, 17-27 [19] K P.Kumar, M Gopi Krishna, J Babu Rao, and NRMR Bhargava “Fabrication and Characterization of 2024 Aluminium - High Entropy Alloy Composites”, Journal of Alloys and Compounds, 640 (2015) 421–427. [20] M Gopi Krishna, K. Praveen Kumar, J.Babu Rao, NRMR Bhargava, K.Vijaya Bhaskar, “Deformation Studies on A2024/Flyash/SiC Hybrid Composites”, International Journal of Engineering Research & Technology, vol. 2, Issue 10, 2013, pp 3772-3776. http://www.iaeme.com/IJMET/index.asp 303 editor@iaeme.com