Effect of Compression Time on Microstructure and Hardness of A356 Fabricated via Thixoforming

Year 2021, Volume: 13 Issue: 3, 9 - 14, 31.12.2021

Bekir Yavuzer , Dursun Özyürek

https://doi.org/10.29137/umagd.1038092

Abstract

This study investigates the effect of compression time and milling on microstructure and hardness of A356 alloy produced by thixoforming, which is one of the semi-solid forming methods. As a result of the microstructure studies, it was determined that there was an increase in the globalization amount of the grains and a decrease in the grain sizes depending on the compression period. The highest globularization rate was measured in the sample, which did not milled and had 2 minutes compression time in the thixoforming process. As a result of the hardness measurements taken from different positions of the samples, it was observed that the hardness values of the samples decreased from the outer surface. The highest hardness value was obtained from the samples produced by compressing for 2 minutes and not milled. In addition, EDS analysis results showed that there is more silicon in the grain boundaries than in the grain.

Keywords

A356, Thixoforming, Microstructure, Hardness

Tikso Şekillendirme ile Üretilen A356 Alaşımında Sıkıştırma Süresinin Mikro Yapı ve Sertlik Üzerine Etkisi

Abstract

Bu çalışmada yarı-katı şekillendirme yöntemlerinden biri olan tikso şekillendirme ile üretilen A356 alaşımında, sıkıştırma süresinin ve ön şekillendirilen tozların deformasyonunun, alaşımın mikro yapı özelliklerine etkisi incelenmiştir. Mikro yapı incelemeleri sonucunda sıkıştırma süresine bağlı olarak tanelerin küreselleşme miktarında artış olduğu, tane boyutlarında ise düşüş meydana geldiği belirlenmiştir. En yüksek küresellik oranı, öğütme işlemi uygulanmamış ve tikso şekillendirme işleminde 2 dakika sıkıştırma süresi kullanılmış olan numunede ölçülmüştür. Numunelerin farklı bölgelerinden alınan sertlik ölçümleri sonucunda, dış yüzeyden itibaren numunelerin sertlik değerlerinde azalma olduğu görülmüştür. En yüksek sertlik değeri öğütme işlemi uygulanmamış ve 2 dakika sıkıştırılarak üretilmiş numunelerden elde edilmiştir. Ayrıca EDS analizi sonuçlarında tane sınırlarında, tane içlerine göre daha fazla silisyum bulunduğu belirlenmiştir.

Keywords

A356, Tikso şekillendirme, Mikro yapı, Sertlik

References

• Atkinson, H. V. (2005). Modelling the semisolid processing of metallic alloys. Progress in Materials Science, 50(3), 341-412. doi:10.1016/j.pmatsci.2004.04.003
• Cho, W. G., & Kang, C. G. (2000). Mechanical properties and their microstructure evaluation in the thixoforming process of semi-solid aluminum alloys. Journal of Materials Processing Technology, 105(3), 269-277. doi: 10.1016/S0924-0136(00)00577-X
• Cree, D., & Pugh, M. (2011). Dry wear and friction properties of an A356/SiC foam interpenetrating phase composite. Wear, 272(1), 88-96. doi: 10.1016 / j.wear.2011.07.008
• Çam, S., Demir, V., & Özyürek D. (2016). Wear behaviour of A356/TiAl3 in situ composites produced by mechanical alloying. Metals, 6(2):34. doi: 10.3390/met6020034
• Dong, J., Cui, J. Z., Le, Q. C., & Lu, G. M. (2002). The key laboratory of electromagnetic processing of material, ministry of education. Northeastren University, SHENYANG.
• Haghshenas, M., Zarei-Hanzaki, A., & Jahanzi, M. (2009). An investigation to the effect of deformation-heat treatment cycle on the eutectic morphology and mechanical properties of a Thixocast A356 alloy. Materials Characterization, 60(8), 817-823. doi: 10.1016/j.matchar.2009.01.020
• Idegomori, T., Hirono, H., Ito, O., Kimishima, S., & Mizoue K., (1998). The manufacturing of automobile parts using semi-solid metal processing. Proceedings of the Fifth International Conference on Semi-Solid Processing of Alloys and Composites, Colorado School of Mines, Colorado.
• Jung, H.K., (2000). The induction heating process of semi-solid aluminium alloys for thixoforming and their microstructure evaluation. Journal of Materials Processing Technology, 105(1-2), 176-190. doi: 10.1016/S0924-0136(00)00567-7
• Jung, H. K., & Kang, C. G., (1999). An induction heating process with coil design and solutions avoiding coarsening phenomena of Al-6 Pct Si-3 Pct Cu-0.3 Pct Mg alloy for thixoforming. Matellurgical and Materials Transactions A, 30, 2967-2977. doi: 10.1007/s11661-999-0134-5
• Kang, C. G., & Jung, G. D., (2001). Improvement of the liquid segregation phenomena of semisolid aluminium alloys by the multistage strain rate control in the compression test. Journal of Materials Engineering and Performance, 10 (4) 419-428. doi: 10.1361/105994901770344836
• Kapranos, P., Kirkwood, D. H., & Sellars, C. M. (1992). Semi-solid forging of high temperature alloys. Proceedings of the Second International Conference on Semi-Solid Processing of Alloys and Composites, Massachusetts Institute of Technology of, Massachusetts.
• Khalifa, W., El-Hadad, S., & Tsunekawa, Y. (2015). Microstructure characteristics and tensile property of ultrasonic treated-thixocast A356 alloy. Transactions of Nonferrous Metals Society of China, 25(10), 3173-3180. doi: 10.1016/S1003-6326(15)63949-8
• Khosravi, H., & Akhlaghi, F. (2015). Comparison of microstructure and wear resistance of A356-SiCp composites processed via compocasting and vibrating cooling slope. Transactions of Nonferrous Metals Society of China, 25(8), 2490-2498. doi: 10.1016/S1003-6326(15)63867-5
• Kouji, S. (1997). The characteristics of thixoforming product. Proceedings of the175th JSTP symposium for Semi-Soild Metals Forming, JSTP & JSME, Tokyo University of Technology, Tokyo.
• Kumar, S., Chakraborty, M., Sarma, V. S., & Murty, B. S. (2008) Tensile and wear behaviour of in situ Al-7Si/TiB2 particulate composites. Wear, 265(1-2), 134-142. doi: 10.1016/j.wear.2007.09.007
• Lee, D. H., Seo, P. K., & Kang, C. G. (2004). Die design by filling analysis of semi-solid injection forging process and their experimental investigation. Journal of Materials Processing Technology, 147(1), 45-50. doi: 10.1016/j.jmatprotec.2003.10.023
• Li, P., Kandalova, E. G., & Nikitin V. I. (2005). In situ synthesis of Al-TiC in aluminum melt. Materials Letters, 59(19-20), 2545-2548. doi: 10.1016/j.matlet.2005.03.043
• Mandal, A., Murty, B. S., & Chakraborty, M. (2009) Sliding wear behaviour of T6 treated A356-TiB2 in-situ composites. Wear, 266(7-8), 865-872. doi: 10.1016/j.wear.2008.12.011
• Otarawanna, S., & Dahle, A.K. (2011). Fundamentals of aluminium metallurgy. Duxford, Woodhead Publishing.
• Pinsky, D. A., Charreyron, P. O., & Flemings, M. C. (1984) Compression of semi-solid dentritic Sn-Pb alloys at low strain rates. Metallurgical Transactions B, 15, 173-181. doi: 10.1007/BF02661076
• Qui, K., Wang, R., Peng, C., Wang, N., Cai, Z., & Zhang, C. (2015) Effect of individual and combined additions of Al-5Ti-B, Mn and Sn on sliding wear behavior of A356 alloy. Transactions of Nonferrous Metals Society of China, 25(12), 3886-3892. doi: 10.1016/S1003-6326(15)64081-X
• Shabani, M. O., & Mazahery, A. (2011) Prediction of wear properties in A356 matrix composite reinforced with B4C particules. Synthetic Metals, 161(13), 1226-1231. doi: 10.1016/j.synthmet.2011.04.009
• Witulski, T., Morjan, U., Niedick, I., & Hirt, G. (1998) The thixoformability of aluminium alloys. Proceedings of the Fifth International Conference on Semi-Solid Processing of Alloys and Composites, Colorado School of Mines, Colorado.
• Yıldırım, M., Özyürek, D., & Tunçay, T. (2017) The effects of molding materials on microstructure and wear behavior of A356 alloy. High Temperature Materials and Processes, 36(5), 515-521. doi: 10.1515/htmp-2015-0240
• Yoshida, C., Moritaka, M., Shinya, S., Takebayashi, K., Nanba, A. (1992) Semi-solid forging of aluminium alloys. Proceedings of the Second International Conference on Semi-Solid Processing of Alloys and Composites, Cambridge, MIT Press.