Hot Forging and Hot Pressing of AlSi Powder Compared to Conventional Powder Metallurgy Route
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Abstract
Aluminum silicon alloy of composition (Al-25%Si-3%Ni-1%Fe-2%Cu) was atomized using water atomization. The powders were cold compacted in a die to produce green cylinder compacts. Four consolidation processes were applied, namely; conventional sintering at 500℃, sintering followed by hot forging to obtain pistons, one step hot forging into pistons, and hot pressing. The microstructure of the sintered specimens showed inter-granular pores and oxide layers on particle interfaces of 84% relative density. When the sintered specimens were hot forged, both the inter-granular pores and oxide layers on particle interfaces almost disappeared and the relative densities increased up to about 95%. The same microstructure is also obtained for the one step forged specimens, but the relative densities increased to about 97%. However, the hot pressing specimens showed the presence of oxide layers on particle surfaces as well as few isolated pores. The relative density of the hot pressed specimens was about 90%. Hardness and ultimate compression strength were measured. It is noted that the strongest bulk materials are those made by hot forging, followed by those made by hot pressing and the weakest bulk materials are those made by conventional sintering.
- T. Hanlon, Y. N. Kwon and S. Suresh, “Grain Size Effects on the Fatigue Response of Nanocrystalline Metals,” Scripta Materialia, Vol. 49, No. 7, 2003, pp. 675-690. doi.org/10.1016/S1359-6462(03)00393-2
- J. Zhou, J. Duszczyk and B. M. Korevaar, “Microstructural Features and Final Mechanical Properties of the Iron-Modified Al-20Si-3Cu-1 Mg Alloy Product Processed from Atomized Powder,” Journal of Materials Science, Vol. 26, No. 11, 1991. pp. 3041-3050. doi.org/10.1007/BF01124840
- P. J. Ward, H. V. Atkinson, P. R. Anderson, L. G. Elias, B. Garcia, L. Kahlen and J. M. Rodriguez, “Semi-Solid Processing of Novel MMCs Based on Hypereutectic Aluminium-Silicon,” Acta Materialia, Vol. 44, No. 5, 1996, pp. 1717-1727. doi.org/10.1016/1359-6454(95)00356-8
- T. H. Lee and S. J. Hong, “Microstructure and Mechanical Properties of Al–Si–X Alloys Fabricated by Gas Atomization and Extrusion Process,” Journal of Alloys and Compounds, Vol. 487, No. 1-2, 2009, pp. 218-224. doi.org/10.1016/j.jallcom.2009.07.108
- M. D. Hanna, S. Lu and A., Hellawell, “Modification in the Aluminum Silicon System,” Metal Transaction A, Vol. 15, No. 3, 1984, pp. 459-469. doi.org/10.1007/BF02644969
- K. D. Woo and S.W. Kim, “Tensile Behavior of Al?4%Mg?0.4%Sc?0.5% Misch Metal Alloy at Room Temperature,” Metals and Materials International, Vol. 11, No. 2, 2005, pp. 95-99. doi.org/10.1007/BF03027452
- S. J. Hong and C. Suryanarayana, “Mechanical Properties and Fracture Behavior of an Ultrafine-Grained Al-20 Wt. % Si Alloy,” Metallurgical and Materials Transactions A, Vol. 36A, 2005, pp. 1-9.
- Z. C. Zhong, X. Y. Jiang and A. L. Greer, “Micro Structure and Hardening of Al-Based Nanophase,” Materials Science and Engineering A, Vol. 226-228, No. 15, 1997, pp. 531-535. doi.org/10.1016/S0921-5093(97)80062-7
- H. S. Kim, “Yield and Compaction Behavior of Rapidly Solidified Al–Si Alloy Powders,” Materials Science and Engineering A, Vol. 251, No. 1-2, 1998, pp. 100-105. doi.org/10.1016/S0921-5093(98)00635-2
- A. K. Srivastavaa, V. C. Srivastavab, A. Gloterc and S. N. Ojhad, “Microstructural Features Induced by Spray Processing and Hot Extrusion of an Al–18% Si–5% Fe–1.5% Cu Alloy,” Acta Materialia, Vol. 54, No. 7, 2006, pp. 1741-1748.
- R. Yearim and D. Shechtman, “The Structure of Rapidly Solidified Al-Fe-Cr Alloys,” Chemistry and Materials Science, Vol. 13, No. 11, 1982, pp. 1891-1898. doi.org/10.1007/BF02645932