IJIRST –International Journal for Innovative Research in Science & Technology| Volume 4 | Issue 2 | July 2017 ISSN (online): 2349-6010
Effect of Mould Vibration on Mechanical and Metallurgical Properties of Aluminum 6063alloy Casting Santhosh Kumar Sape PG Student Department of Mechanical Engineering Gudlavalleru Engineering College, AP.
T. Naga Raju Assistant Professor Department of Mechanical Engineering Gudlavalleru Engineering College, AP.
Abstract Casting is one of the oldest and mostly used production methods in industry. The traditional casting has certain disadvantages like poor strength due to hot tears, shrinkage and poor surface finish. The properties of casted product mostly depend on the microstructure after solidification. Providing Mould vibration during casting is one of the latest techniques employed in order to get better structure in the solidified casting. Mould vibration during casting gives reduced amount of shrinkage, better morphology, surface finish, and less chances of hot tear. In this research work the effect of mould vibration on casting during solidification of Al-6063 alloys for different values of wave lengths at fixed pouring temperatures is investigated to understand the changes in microstructure and mechanical properties of casting .The casting has been prepared in iron EN8 mould with and without vibrations. The frequencies varied from 0Hz to 40 Hz. A casting has been made without vibration as well to compare the results of castings with vibration. The experimental results showed significant grain refinement and remarkably improvement in mechanical properties of casting with mechanical mould vibration during solidification. Keywords: Aluminum 6063 alloy, mould vibration, Vibration table, microstructure analysis, Hardness test Impact test, Wear test. Grain refinement _______________________________________________________________________________________________________ I.
INTRODUCTION
Now a day’s more than 85% of products are produced by casting processes. The totality of metals and alloys begin to work by a very important operation, that of solidification. Solidification is the operation that gives shape and structure. Currently the solidification technique has experienced a rapid development. Because of progresses made as yet the castings are used in high security parts in the aero-spatial industry, the automotive, chemical and metallurgical equipment [1]. Recent techniques suggest that, mold vibration during pouring and till solidification is one of the important methods to produce casting for better morphology, surface finish and reduced amount of shrinkage [2]. Mold conditions, pouring temperature, frequency of vibration and other process variables are factors that would have a definite effect on the microstructure and properties of the cast [3]. Investigated the mechanical vibration causes improvement in mechanical and corrosion properties of alloys. The mechanical mold vibration on liquid metallic materials and their crystallization has a significant effect on the grain structure of the casting, grain size reduced by vibration and grain became more compact. II. SELECTION OF MATERIAL Material examined in this work is aluminum 6063, the basic composition and mechanical properties of Al-6063. component %Wt
Si 0.6
Tensile Strength (N/mm^2) 150
Table - 1 Chemical Composition u Mg Cr Ti Fe Mn Al Zn 0.1 0.9 0.1 0.1 0.35 0.1 97.5 0.1 Table - 2 Mechanical Properties Hardness Modulus of Elasticity Elongation (RHB) (N/mm^2) (%) 50 71 12
III. METHODOLOGY Preparation of specimen: specimen prepare is casted in two phases
Preparation of casting without vibration
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Effect of Mould Vibration on Mechanical and Metallurgical Properties of Aluminum 6063alloy Casting (IJIRST/ Volume 4 / Issue 2 / 015)
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Preparation of casting with vibrations [25Hz, 30Hz, 35Hz, 40Hz] Preparation of casting specimen without mould vibration The cut pieces are placed into the crucible, and then the crucible is placed in muffle furnace. Heat the crucible up to 7200c (above melting temperature of Al-6063). While the crucible is taken out at the temperature of 690oc and stir the solution with stirrer. After stirring process the crucible is again placed in the furnace and then heated up to 7200c. At 7200C the crucible is taken out and add small amount of c2cl6 (approximately ½ spoon) stir the solution and poor into the die. Leave the die up to 10 minutes to solidification. After solidification process the dies is separated and collect the casted object. The process repeated till required number of products obtained. Preparation of casting specimens with mould vibration The above same process is used to make the products with vibrations apart from that the vibrations created by placing the die on vibrating table. The die is placed at different frequencies. By changing the frequency values (25Hz, 30Hz, 35Hz, and 40Hz). This process is repeated till required number of products obtained at required frequencies.
Fig. 3: Die should be placed on Vibrating table
Fig. 4: Muffle furnace
Heat treatment process Casted product need to conducted Heat Treatment process there by controlled heating and cooling. In this process, we heated samples temperature to 1550C and soaked the sample at temperature about 2hr.After that we quenched the sample in water at temperature of 150C. Testing of Specimens Specimen preparation of Impact test Casting prepared with dimension 15*15*60 at different frequencies 0, 25, 30, 35 and 40 Hz .After that the specimen is machined to standard dimension [E3] i.e. 10*10*55. Shown in fig-5.
Fig. 5: Specimen Dimensions
Impact test samples with and without vibration are shown in figure 6, 7 respectively.
Fig. 6: Specimen for Impact Test without Vibration
Fig. 7: Specimen for Impact test with vibration
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Effect of Mould Vibration on Mechanical and Metallurgical Properties of Aluminum 6063alloy Casting (IJIRST/ Volume 4 / Issue 2 / 015)
Specimen preparation of Hardness test: We selected three different positions in the samples for hardness test. By cutting the total casted specimen into 2 parts, First - top position of casted sample part, Second- bottom position of top casted sample part/middle position of casted sample part, Thirdmiddle position of casting part (top position of bottom sample part)specimen prepared ready for Hardness test by making surface smooth.
Fig. 8: Specimen for Hardness Test without Vibration
Fig. 9: Specimen for Hardness Test with Vibration
Wear testing Initially the castings were made with the dimension of 15*15*60, after that the specimen machined and converted to the standard dimensions ø10 lenth30mm. The wear test is conducted with pin and disc wear test apparatuses. Specimen tested at constant time and variable loading. The results are shown in table 6. And graph 3.
Fig. 10: Specimen for Wear test without Vibration
Fig. 11: Specimen for Wear Test with Vibration
Microstructure Microstructure test is conducted on computerized microscope. The total casted specimen is cut into 2 equal parts. Specimen is processed all metallographic stages, make it ready for microstructure test.
Fig. 12: Specimen for Microstructure analysis without Vibration
Fig. 13: Specimen for Micro Structure analysis with Vibration
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Effect of Mould Vibration on Mechanical and Metallurgical Properties of Aluminum 6063alloy Casting (IJIRST/ Volume 4 / Issue 2 / 015)
IV. RESULTS AND DISCUSSIONS Impact Test Results Table – 3 Impact Test Results Frequency(Hz) Specific Impact strength 0 3.125 25 3.175 30 3.189 35 3.405 40 2.125
Graph 1: Frequency Vs specific Impact strength
Specific Impact strength of the cast samples are shown at different frequencies in the table 3. It is clear that the impact strength of the casting increases from a frequency of 0-35 Hertz and beyond that ( at 40HZ) there is a reduce in the impact strength of the specimen. We can observe that the material has high impact strength at a frequency of 35HZ. The variation frequency v/s specific impact strength is shown in graph 1. Hardness test Results Table - 4 Hardness Test Results at frequency Hardness(RHB) Methodology No of specimens No of trails 1 2 3 1 44 45 46 Without vibration 2 47 44 45 1 53 49 42 With vibration at 25Hz 2 47 47 48 1 53 55 48 With vibration at 30 Hz 2 57 53 48 1 55 57 53 With vibration at 35 Hz 2 59 53 53 1 61 62 63 With vibration at 40 Hz 2 62 65 59 Table - 5 Average Hardness Test Results Frequency(Hz) Hardness(RHB) 0 45 25 47.8 30 53 35 55 40 62
Average(RHB) 45 45.33 48 47 52 54 55 55 62 62
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Effect of Mould Vibration on Mechanical and Metallurgical Properties of Aluminum 6063alloy Casting (IJIRST/ Volume 4 / Issue 2 / 015)
Graph 2 Frequency Vs Hardness
Hardness of the casted samples is shown in table 4 and Average hardness test results are shown in table 5. It is clear that hardness of casting increases with the increase of vibration frequency. The vibrations during solidification lead to refinement of grains. The highest hardness is obtained at the bottom of each and every sample, because highest cooling rate and vibration intensity at the bottom of sample, it is evident from the microstructure. More cooling action promotes creation of fine grain and at the same the vibration procedure fine grains. That means more grain boundary more hardness. So we may be concluded that due to combined effect of cooling rate and intensity of vibration, there are remarkable changes of hardness in the cast product. The variation of hardness is plotted on graph 2. Wear testing Table - 6 Wear testing values for deferent Frequency (Hz) Frequency Weight Time Wear rate S.no (Hz) (kg) (min) (Âľ) 0.5 10 72 1 0 1.0 10 104 0.5 10 57 2 25 1.0 10 86 0.5 10 52 3 30 1.0 10 84 0.5 10 65 4 35 1.0 10 184 0.5 10 76 5 40 1.0 10 410
Graph 3 frequency v/s wear rate
These results are saying, the wear resistance increasing by increases of mould vibrations. It is shown at different loads (0.5 Kg and 1 Kg) in table 6. As we increasing vibration frequency during solidification of casting wear resistance is increasing at 0.5 kg load. But at 1.0kg load up to 30Hz vibrations the wear resistance is increasing beyond that it in decreasing.
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Effect of Mould Vibration on Mechanical and Metallurgical Properties of Aluminum 6063alloy Casting (IJIRST/ Volume 4 / Issue 2 / 015)
Microstructure Results By increasing the frequency of vibrations the grain are refined, this can be seen in following figures 14, 15, 16, 17 and 18. The microstructure test results (images) saying that refinement of grains can observed on increasing of vibration.
Top part of the cast Bottom part of the cast Fig. 14: Microstructure without vibration
Top part of the cast Bottom part of the cast Fig. 15: Microstructure with frequency at 25Hz
Top part of the cast Bottom part of the cast Fig. 16: Microstructure with frequency at 30Hz
Top part of the cast Bottom part of the cast Fig. 17: Microstructure with frequency at 35Hz
Top part of the cast Bottom part of the cast Fig. 18: Microstructure with frequency at 40Hz
V. CONCLUSION The main conclusion is that creation of vibration on mould during solidification of casing gives good mechanical properties and metallurgical properties. The following are the specific conclusions we can say 1) Mould vibration during casting provides good impact strength and best impact strength at 35 HZ. 2) By increasing the mould vibrations of the casting the hardness increases. 3) Mould vibration during casting gives good wear strength. 4) The vibration in the casting procedure gives refinement of grains. REFERENCES [1] [2] [3]
Crenguta Manuela Pîrvulescu, Constantin Bratu, “Mechanic Vibrations Generation System and Effect on the Casting Alloys Solidification Process”, U.P.B. Sci. Bull., Series B, Vol. 72, Iss. 3, 2010 ISSN 1454-2331. Deshpande J., “The effect of mechanical mold vibration on the characteristics of Al-alloy”, 2006, Ph.D. thesis, Worcester polytechnic institute. S.S. Mishra, S.S Sahu, V. Ray, “Effect of Mold Vibration on Mechanical and Metallurgical Properties of Al-Cu Alloys”, IJTRE Volume 3, Issue 1, September2015 ISSN (Online): 2347 – 4718.
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