Evaluation of Al-5Ti-1B and Al-10Sr in LM6 sand castings

• Autorzy: Lim Y. P.
• Języki publikacji: EN

Abstrakty

EN

Purpose: of this paper is to study the separate effects of grain refiner and modifier on the metallurgical properties of LM6 sand castings. The research aims to determine how grain refiner and modifier will influence the microstructure of LM6 sand casting and the associated mechanical properties of hardness, ultimate tensile strength and engineering strain. Design/methodology/approach: A grain refiner consists of 0.5wt% Al-5Ti-1B and a modifier consists of 0.5wt% Al-10Sr have been introduced separately into the melt of hypoeutectic LM6 Al-Si alloy to produce slab castings by CO2 sand casting process. The geometry of the slab casting is designed to have different section moduli to induce directional solidification. Temperature profile of cooling process is taken to correlate between the section modulus and cooling rate. This enables the effect of cooling rate on microstructure and mechanical properties to be studied for grain refined and modified LM6 sand castings. Findings: The significant finding is that a nearly full eutectic solidification at 540°C is achieved in the Sr-modified casting with faster cooling rates than those of solely grain-refined and original LM6. The hardness and ultimate tensile strength can be improved respectively between 20~40% and 11~18% by Al-10Sr modifier. It is observed that the Al-5Ti-1B grain refiner and Al-10Sr modifier increase the strain at UTS by 11% and 22% respectively. The metallographic observations show that the eutectic phase is finer and in fibrous form in the Sr-modified LM6. Research limitations/implications: Further research can study a wider range of inoculant percentage. Practical implications: This eutectic solidification at 540°C achieved in Sr-modified LM6 is lower than the solidus temperature of LM6 to reduce superheat and save electrical energy consumption while ensuring complete liquid mould filling. Originality/value: This is the original work of slab casting of LM6 and the effects of Sr modifier and TiB grain refiner on its metallurgical properties.

Słowa kluczowe

EN

casting; modification; grain refinement; eutectic solidification

PL

odlewnictwo; modyfikacja; rafinacja ziaren; krzepnięcie eutektyczne

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2009
• Tom: Vol. 34, nr 1
• Strony: 71--78
• Opis fizyczny: Bibliogr. 17 poz., rys., tabl.

Twórcy

autor

Lim Y. P.

• Department of Mechanical and Material Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kuala Lumpur, Malaysia,

Bibliografia

• [1] G. Mathers, The Welding of Aluminium and Its Alloys, CRC Press, 2002, 35-46.
• [2] F. Yilmaz, O. A. Atasoy, Growth Structures in Al-Si Alloys II - The Influence of Strontium, Journal of Crystal Growth 118 (1992) 377-384.
• [3] R. Cook, P. S. Cooper, M. A. Kearns, Benefits of Master Alloy Melt Treatments in the Aluminium Foundry Industry, Proceedings of the 125th Anaheim Annual Meeting,1996.
• [4] D. M. Stefanescu, Science And Engineering of Casting Solidification, Kluwer Academic/Plenum Publishers, 2002, New York, 311-319.
• [5] G. K. Sigworth, M. M. Guzowski, Grain Refining of Hypoeutectic Al-Si Alloys, AFS Transactions 93 (1985) 907-912.
• [6] K T. Kashyap, T. Chandrashekar, Effects and mechanisms of grain refinement in aluminium alloys, Bulletin of Materials Science 24/4 (2001) 345-353.
• [7] Y. P. Lim, S. Sulaiman, An Experimental Investigation on LM6 AL-SI Alloy Sand Casting To Study The Correlation Between Metallurgical Properties And Solidification Rate, Proceedings of the Conference “Advanced Materials”, Putrajaya, 2005.
• [8] W. Rostoker, J. R. Dvorak, Interpretation of Metallographic Structures, Academic Press, 1977, 70-90.
• [9] E. J. Martinez D., M. A. Cisneros G., S. Valtierra, J. Lacaze, Effect of strontium and cooling rate upon eutectic temperatures of A319 aluminium alloy, Scripta Materialia 52 (2005) 439-443.
• [10] J. Campbell, Castings, Butterworth Heinemann, 1991, 130-131.
• [11] M. Dash, M. Makhlouf, Effect of key alloying elements on the feeding characteristics of aluminum-silicon casting alloys, Journal of Light Metals 1 (2001) 251-265.
• [12] K. Nogita, A. K. Dahle, Effects of boron on eutectic modification of hypoeutectic Al-Si alloys, Scripta Materialia 48 (2003) 307-313.
• [13] S. A. Kori, B. S. Murty, M. Chakraborty, Development of an efficient grain refiner for Al-7Si alloy and its modification with strontium, Materials Science and Engineering A 283 (2000) 94-104.
• [14] A. K. Dahle, K. Nogita, J. W. Zindel, S. D. McDonald, L. M. Hogan, Eutectic nucleation and growth in hypoeutectic Al-Si alloys at different strontium levels, Metallurgical and Materials Transactions A 32 (2001) 949-960.
• [15] K. Nogita, A. K. Dahle, Determination of eutectic solidification mode in Sr-modified hypoeutectic Al-Si alloys by EBSD, Materials Transaction 42/2 (2001) 207-214.
• [16] C. Limmaneevichitr, W. Eidhed, Fading mechanism of grain refinement of aluminum-silicon alloy with Al-Ti-B grain refiners, Materials Science and Engeneering A 349 (2003) 197-206.
• [17] P. S. Mohanty, J. E. Gruzlesky, Mechanism of grain refinement in aluminium, Acta Metallurgical Material 43/5(1995) 2001-2012.