通過砂鑄壓鑄和離心鑄造技術(shù)對(duì)Al C355.0的力學(xué)表征和顯微組織分析【中文2700字】【PDF+中文WORD】,中文2700字,PDF+中文WORD,通過砂鑄,壓鑄和離心鑄造技術(shù)對(duì)Al,C355.0的力學(xué)表征和顯微組織分析【中文2700字】【PDF+中文WORD】,通過,壓鑄,離心,鑄造,技術(shù),Al,C355,力學(xué) Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 4 (2017) 10987–10993 www.materialstoday.com/proceedings AMMMT 2016 Mechanical Characterization and Microstructure analysis of Al C355.0 by Sand Casting, Die Casting and Centrifugal Casting Techniques. Santosh M V* , Suresh K R, Kiran Aithal S Department of Mechanical engineering, NMIT Bangalore, Karnataka, India Abstract In this study, mechanical properties of aluminium alloy C355.0 was investigated for Sand Casting, Die Casting and Centrifugal Casting Technique. Mechanical properties like tensile test was performed using PC2000 software, and Brinell hardness test was performed. Die casting was observed to have good tensile and hardness properties compared to sand and centrifugal castings Microstructure analysis was done by Nikon Microscope LV150with Clemax Image Analyser. From the observation die casting had uniform distribution of silicon. Wear behavior of the alloy studied using sliding wear test. Good wear specific wear rate was found in all the casting but the best was observed in die casting at 20N load. ? 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of Advanced Materials, Manufacturing, Management and Thermal Science (AMMMT 2016). Keywords: Die casting; sand casting; centrifugal casting; mechanical and sliding wear properties. 1. Introduction Aluminum is light and possesses high strength it is an important metal in automotive and aerospace industries. Generally pure aluminum does not fit the standards of the industries, therefore, they are alloyed with silicon, copper, magnesium and many other metals to increase strength and other properties on the aluminum among them Al-Si-Cu-Mg alloy system is one them. Al-Si-Cu-Mg system is the most used alloy group in the industries because of excellent castability and mechanical properties. The applications are from aerospace to automobile to household industries. Therefore this alloy system is very important among them C355.0 in one the alloy. The main alloying ingredient are silicon and copper, the increase in silicon content will increase the hardness of the alloy * Corresponding author. Tel.: +91-948-118-8859; E-mail address: santoshmv9632@gmail.com 2214-7853 ? 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of Advanced Materials, Manufacturing, Management and Thermal Science (AMMMT 2016). 10988 Santosh M V/ Materials Today: Proceedings 4 (2017) 10987–10993 system and increase in copper upto strength (yield and ultimate) increased[1-10, 13]. Also with the increase in load and sliding distance volume loss increased but friction co-efficient was constant for the sliding distance, but also friction co-efficient diminishes with longer sliding distance[11,12]. In this paper, an attempt is made to compare mechanical characteristics of different casting techniques that are generally used in industries namely gravity die casting, sand casting. Also since in automotive industries friction wear plays an important role sliding wear behavior are also analyzed. 2. Materials The chemical composition of aluminum alloy C355.0 is shown in the Table 1. Properties of Aluminum are shown Table 2. Aluminum has a FCC crystal structure with lattice parameters a=0.405nm and atomic radius R=0.143nm. Aluminum C355.0 is a hypoeutectic alloy because %wt. of silicon is less than 12%. Table 1 Chemical Composition of C355.0 alloy, %wt. Elements % wt. Cu 1.32 Mg 0.34 Si 5.05 Fe 0.15 Mn 0.01 Ni 0.02 Zn 0.01 Pb 0.01 Sn 0.01 Ti <0.01 Other(Total) 0.05 Al 93.05 Table 2 Properties of Aluminum Properties Values Density 2.67g/cc3 Melting Point 557-613°C Elastic Modulus 72.4GPa Poisson’s Ratio 0.33 3. Methodology 3.1. Casting Techniques Fabrication of the alloy was carries out in three casting techniques namely gravity die casting, sand casting and centrifugal casting. The alloy was melted to 800°C in a graphite crucible. For gravity die casting a die of diameter 12mm height of 25mm was used. In sand casting mold with diameter 12mm and height of 15mm was prepared and molten metal was poured to obtain casting. In centrifugal casting a cylinder was obtained of outside diameter 60mm and height 120mm. 3.2. Microstructure Study The surface for microstructure study was prepared by etching a surface using 220, 400, 600, and 1000 grade papers and further polished by Keller’s solution i.e., 0.5% of HF in 50ml of H2O. It was observed using Nikon Microscope LV150 with Clemex Image Analyser. Santosh M V/ Materials Today: Proceedings 4 (2017) 10987–10993 10989 3.3. Tensile Test The tensometer used was run by DC servo motors and accompanied with PC2000 software. From the obtained casting tensile specimen were machined according to ASTM E8 standards. The dimensions are gauge diameter 6.25mm and gauge length of 25mm with overall length 50mm. 3.4. Wear Test Wear specimen were machined according to ASTM G99 standards. Dry sliding wear test was conducted different load conditions at room temperature. The diameter was of 10mm and length 30mm. The surface etched with 600 grade paper to fit standards of the pin-on-disc apparatus used in the investigation. 3.5. Hardness Test Hardness test was conducted using Brinell Hardness Equipment with load 250kg-f with indentation ball diameter 10mm was applied for 30sec. The indentation was made on the surface which as measured by traveling microscope and BHN was calculated by the measured indentations. 4. Results and Discussions 4.1. Microstructure Evaluation 4.1.1. Die Casting In die casting the silicon particles are uniform distributed among the primary phase and α-Al matrix is found. Fig. 1 shows the un-etched surface of the as-cast obtained. The size of dendrite size and inter-dendrite arm spacing is small because of faster and uniform cooling rate as shown in fig. 2. Fig. 1 Unetched surface of Die Casting at 100X. Fig. 2 Keller’s etched surface of Die Casting at 100X. 4.1.2. Sand Casting The fig. 3 shows the un-etched surface of the sand casting technique. From the observation of fig 4 the dark dots are the existence of the porosity and impurities during casting process. From fig. 4 it is observed that the dendritic and inter-dendrite space is small. The investigation of fig. 4 the solid solution of α-Al matrix is found and an intermetallic secondary phase of β-Si. The β-Si phase is observed as large flakes, needles and fibrous precipitations 10990 Santosh M V/ Materials Today: Proceedings 4 (2017) 10987–10993 for the variation of Cu concentration. Since the Si needles exist there are chances of notching to occur which decreases the mechanical properties. Fig. 3 Unetched surface of Sand Casting at 100X. Fig. 4 Keller’s etched surface of Sand Casting at 100X. 4.1.3 Centrifugal Casting Porosity in centrifugal casting is shown in the fig. 5. The silicon is unevenly distributed in the primary phase. A large amount of Al2Cu is formed in the secondary phase along with α-Al matrix. Since the Si needles exist there are chances of notching to occur which decreases the mechanical properties. The dark spots in fig. 6 shows scattered magnesium. Fig. 5 Unetched surface of Centrifugal Casting at 100X. Fig. 6 Keller’s etched surface of Centrifugal Casting at 100X. Santosh M V/ Materials Today: Proceedings 4 (2017) 10987–10993 10991 4.2 Hardness Test  Fig. 7 Hardness Test BHN was calculated by measuring the indentation diameter which was made on the surface. An average was taken of three indentations and shown fig. 7. Centrifugal casting had high hardness because it was found to be ductile in nature when compared to die casting which had least hardness which good ductile property as shown in section 4.3. 4.3 Tensile Test Fig. 8 shows the variation in the strength of castings fabricated. Best strength was obtained in gravity die casting and worst in centrifugal casting. Uniform distribution of silicon and less impurities and good casting techniques increased the strength, whereas, porosity, blowholes present in centrifugal casting had least strength. On the other hand, in sand casting porosity, bad casting technique and the presence of silicon needles which causes notching effect had moderate strength. The % elongation of the specimen is shown in fig. 9. The engineering ultimate strength of die casting was better by 57% compared to centrifugal casting and by 47% to that of sand casting. Fig. 8 Tensile Test 10992 Santosh M V/ Materials Today: Proceedings 4 (2017) 10987–10993 Fig. 9 %Elongation of the specimen 4.4. Wear Test Specific wear rate remains constant irrespective of load in sand and centrifugal casting. The sliding distance used is 2500m with sliding speed of 763rpm for 10min with track diameter of 100mm and wear test normal load was conducted for 10N, 20N and 30N. Fig 10 shows the specific wear rate of aluminum C355.0. From fig.10 it can be observed that specific wear rate reduces for increases in load. Fig. 10 Specific wear rate 5. Conclusion From the investigation on the casting techniques following conclusion was drawn: · Microstructure evaluation showed that in die casting fine eutectic silicon dispersed in the inter-dendritic region and fine precipitation of alloy elements in Al solid solution. In sand and centrifugal casting method needles dispersed in the inter-dendritic region was found. · Best hardness of 74HB was found in die casting and least 53HB in sand casting. Centrifugal casting had a good hardness with 69HB. · Strength of Al C355.0 was best obtained using die casting method where engineering stress was found to be 212MPa. Santosh M V/ Materials Today: Proceedings 4 (2017) 10987–10993 10993 · Die casting had good specific wear rate compared to sand and centrifugal casting. Also specific wear rate decreases with increases in load. Overall best casting method is die casting which provides good strength and wear properties. Even with high initial cost for the manufacture of the die on the longer run for mass production die casting is favorable. 6. Acknowledgement We thank Dr. H.C.Nagaraj, Principal and Management of Nitte Meenakshi institute of Technology, Bangalore, India for motivating and providing research facilities at the institute. References 1. Zeren, M. (2005). Effect of copper and silicon content on mechanical properties in Al – Cu – Si – Mg alloys, 169, 292–298. http://doi.org/10.1016/j.jmatprotec.2005.03.009 2. Labisz, K., Krupiński, M., & Dobrzański, L. A. (2009). Phases morphology and distribution of the Al-Si-Cu alloy, 37(2), 309–316. 3. Elmadagli, M., Perry, T., & Alpas, A. T. (2007). A parametric study of the relationship between microstructure and wear resistance of Al – Si alloys, 262, 79–92. http://doi.org/10.1016/j.wear.2006.03.043 4. Dwivedi, S. P., Sharma, S., & Mishra, R. K. (2014). 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