Effects of Pouring Temperature and Electromagnetic Stirring on Porosity and Mechanical Properties of A357 Aluminum Alloy Rheo-Diecasting
- 77 Downloads
Semisolid slurry of A357 aluminum alloy was prepared using a temperature-controllable electromagnetic stirrer and rheo-diecast at different temperatures. The effects of pouring temperature and electromagnetic stirring (EMS) on the porosity in rheo-diecast samples, as well as the relation between porosity and mechanical properties, were investigated. The results show that pouring temperature and EMS had minor influences on rheo-diecast microstructure but marked influence on the porosity. With decreasing slurry pouring temperature, the porosity decreased first and then increased, whereas the maximum pore ratio (ratio of shape factor to diameter of the largest pore) increased first and then decreased. The maximum pore ratio determines the level of tensile strength and elongation, and higher mechanical properties can be obtained with smaller and rounder pores in samples. The mechanical properties of the rheo-diecast samples increased linearly with increasing maximum pore ratio. The maximum pore ratio was 1.43 µm−1, and the minimum porosity level was 0.37% under EMS condition for the rheo-diecast samples obtained at a pouring temperature of 608 °C. With this porosity condition, the maximum tensile strength and elongation were achieved at 274 MPa and 4.9%, respectively. It was also revealed that EMS improves mechanical properties by reduction in porosity and an increase in maximum pore ratio.
KeywordsA357 aluminum alloy electromagnetic stirring (EMS) mechanical properties porosity pouring temperature rheo-diecast
This research was supported by National Key Technology Support Program of China (2015BAG12B01).
- 2.B. Skallerud, T. Iveland, and G. Harkegard, Fatigue Life Assessment of Aluminum Alloys with Casting Defects, Int. J. Fatigue, 1993, 44(6), p 857–874Google Scholar
- 6.Y.F. Yan and S.M. Xiong, Effects of Casting Pressure Parameters on Porosities and Tensile Strength of a High Pressure Die Cast ADC12Z Alloy, Rare Metal Mater. Eng., 2010, 39(a01), p 219–222 (in Chinese)Google Scholar
- 9.Q. Wan, H.D. Zhao, and J.L. Ge, Effect of Micro-Porosities on Fatigue Behavior of Aluminum Die Castings, Chin. J. Nonferrous Met., 2015, 25(3), p 568–574 (in Chinese)Google Scholar
- 20.Z. Yang, P.K. Seo, and C.G. Kang, Grain Size Control of Semisolid A356 Alloy Manufactured by Electromagnetic Stirring, J. Mater. Sci. Technol., 2005, 21(2), p 219–225Google Scholar
- 21.W.M. Mao, Y.L. Bai, and G.X. Tang, Preparation for Semi-Solid Aluminum Alloy Slurry Under Weak Electromagnetic Stirring Conditions, J. Mater. Sci. Technol., 2006, 22(4), p 447–451Google Scholar
- 26.Y.L. Zhu, J.W. Zhao, W. Li, Z.Y. Zhu, G.Z. Dai, and K. Zhang, Effect of Electromagnetic Stirring on Microstructure of Large-Volume Semi-Solid Slurry of 7A04 Aluminum Alloy, Chin. J. Nonferrous Met., 2014, 24(11), p 2735–2742 (in Chinese)Google Scholar