National University of Science and Technology MISiS, Moscow, Russia:

Yu. N. Mansurov, Professor of the Department of Metals Science of Non-Ferrous Metals, e-mail: yulbarsmans@gmail.com
N. V. Letyagin, Graduate Student of Department of Metal Forming
A. S. Finogeyev, Graduate Student of Department of Metal Forming

Navoi State Mining Institute, Navoi, Uzbekistan:

J. U. Rakhmonov, Senior Lecturer of Department of Machine-building Technology, e-mail: jovid.rakhmonov@googlemail.com

Increasing demand for industrial applications of aluminum alloys achieved a new aspect; nowadays the demand for corrosion-resistant alloys largely exceeds the one for other high-strength, wear-resistant and heat-resistant aluminum alloys. Moreover, the relatively low-cost of casting technology provides an increased share of demand for foundry corrosion-resistant alloys in comparison with the deformable ones. Another advantage of foundry Al alloys is their excellent recyclability. However, recycling of scrap metals causes an increase in the content of impurity elements. In this study, the influence of individual and combined addition of impurity elements, such as Si, Fe, Cu, Zn, Pb, Sn, Ni and Mn, on the casting properties of corrosion-resistant Al – Mg alloy with the Mg content ranging between 4–8% was investigated. While the microstructure of the alloys in as-cast state was characterized using optical and scanning electron microscopes, the fractured surfaces of tensile test specimens were investigated using the latter microscope. The results of the experimental investigations of the effect of the main impurities on casting properties, such as fluidity, hot cracking, shrinkage and pre-shrinkage expansion of Al – Mg based alloys have been systematically summarized. It has been found that among various impurity elements, Si, Fe and Cu can exert much greater influence on fluidity and hot tearing. All these elements tended to improve fluidity; however, it occurred at the expense of a considerable reduction in hot tearing of Al – Mg alloys. The casting properties of die castings, castings obtained under pressure and die castings after hot isostatic pressing (HIP) have been studied and compared with each other and it has been found that isostatic pressing causes reduction of porosity in alloys, but slightly affects the mechanical properties. Casting with excess gas pressure (P = 0.7 atm) exerted almost no apparent influence on density (porosity) of the castings from various alloys. In general, the increased content of impurities has an insignificant effect on the casting properties of Al – Mg based alloys, so it is concluded that low-grade (secondary or recycled) aluminum can be used in the fabrication of corrosion-resistant applications.

The work was carried out with support of grant # РНФ 14-19-00632-П.

1. Novikov I. I., Zolotorevskiy V. S., Lisovskaya T. D. Research of non-ferrous metal alloys. Moscow: AN SSSR, 1963. No. 4. 130 p.
2. Dobatkin V. I., Elagin V. I., Fedorov V. M. Rapidly solidified Al alloys. Moscow: VILS, 1995. 341 p.
3. Belov N. A., Aksenov A. A., Eskin D. G. Multicomponent Phase Diagrams: Applications for Commercial Aluminum Alloys. Elsevier, 2005. 414 p.
4. Zolotorevskiy V. S., Belov N. A., Glazoff M. V. Casting Aluminum Alloys. Elsevier, 2007. 544 p.
5. Mansurov Yu. N., Korolkov G. A., Ramazanov S. M. Influence of impurities on casting and mechanical properties of Al-Mg based alloys. Tsvetnaya metallurgiya. 1986. No. 5. pp. 80–85.
6. Mansurov Yu. N., Gusarov M. N. Dependence of mechanical properties of Al – Mg based alloys with high impurity contents on the cooling rate during solidification. Tsvetnye Metally. 1988. No. 2. pp. 69–71.
7. Knipling K., Dunand D., Seidman D. Precipitation evolution in Al – Zr and Al – Zr – Ti alloys during isothermal aging at 375–425 ^оC. Acta Materialia. 2008. No. 56. pp. 114–127.
8. Aksenov A. A., Belov N. A., Zolotorevskii V. S., Istomin-Kastrovskii V. V., Mansurov Y. N. Microalloying of high-strength cast-aluminum alloys with high iron and silicon content. Russian metallurgy. 1988. No. 1. pp. 112–117.
9. Zolotorevsky V. S., Belov N. A., Mansurov Yu. N. Morphology and Composition of Iron-Containing Phases in Foundry Magnaliums. Izvestiya Vysshikh Uchebnykh Zavedeniy. Tsvetnaya Metallurgiya. 1986. No. 4. pp. 85–90.
10. Denholm W. T., Esdaile J. D., Siviour N. G., Wilson W. The Nature of the FeAl₃. Liquid-(FeMn)Al6 Reaction in the Al – Fe – Mn System. Metall. Trans. A. 1984. Vol. 15A, No. 7. pp. 1311–1317.
11. Miroshnichenko I. S. (ed.). Structure and properties of rapidly solidified alloys. Collection of articles. Dnepropetrovsk: DGU. 1988.
12. Zhang L., Dua Y., Steinbach I., Chen Q., Huang B. Diffusivities of an Al – Fe – Ni melt and their effects on the microstructure during solidification. Acta Materialia. 2010. No. 58. pp. 3664–3675.
13. Wang Q., Praud M., Needleman A., Kim K., Griffiths J., Davidson C., Caceres C., Benzerga A. Size effects in aluminium alloy castings. Acta Materialia. 2010. No. 58. pp. 3006–3013.
14. Mohamed A., Samuel F., Alkahtani S. Microstructure, tensile properties and fracture behavior of high temperature Al – Si – Mg – Cu cast alloys. Materials Science and Engineering: A. 2013. No. 577. pp. 64–72.
15. Changa H., Kellya P., Shib Y., Zhanga M. Effect of eutectic Si on surface nanocrystallization of Al – Si alloys by surface mechanical attrition treatment. Materials Science and Engineering: A. 2011. No. 530. pp. 304–314.
16. Bo L., Wei W. Z., Zhao H. L., Da T. Z., Yuan Y. I. Comparative study on microstructures and mechanical properties of the heat-treated Al – 5.0Cu – 0.6Mn – xFe alloys prepared by gravity die casting and squeeze casting. Materials and Design. 2014. No. 59. pp. 10–18.
17. Røyset J., Ryum N. Proc. 4^th Int. Conf. on Aluminium alloys. 1994. No 1. pp. 194–201.
18. Belov N. A., Naumova E. A., Bazlova T. A., Alekseeva E. V. Structure, Phase Composition, and Strengthening of Cast Al – Ca – Mg – Sc Alloys. The Physics of Metals and Metallography. 2016. No. 2. pp. 199–205.
19. Belov N. A., Naumova E. A., Akopyan T. K., Doroshenko V. V. Phase Diagram of Al – Ca – Mg – Si System and Its Application for the Design of Aluminum Alloys with High Magnesium Content Metals. Open Access Metallurgy Journal. 2017. Vol. 7, Iss. 10. 429 p.