FORMATION OF THE STRUCTURE AND PROPERTIES OF CAST ALUMINUM ALLOY IN THE EXTREMELY DEFORMED STATE
The purpose of the study is to solve the urgent problem of satisfaction the needs of mechanical engineering in deformable aluminum alloys with the simultaneous actual absence of their domestic production through the development of deformable alloy based on foundry alloy AK7h. To achieve this goal, it is necessary to study the effect of microalloying and crystallization conditions on the structure of the extremely deformed alloy AlSi7 to control the structure and properties in the development of deformable alloys based on AK7h.
Methods. Extremely deformed hypo-eutectic AlSi7 based alloys with strontium and scandium additives were studied in this work. The experiment was performed according to the plan of Orthogonal Latin squares. The microstructure was studied on an Axiovert - 200MAT optical microscope. The parameters of the quantitative characteristics of the structure were determined by standard methods. The microhardness of the eutectic was measured on PMT-3 according to ДСТУ ISO 6507-1: 2007. Phase identification was carried out by the method of phase X-ray diffraction analysis on a DRON-3M diffractometer in Coka filtered radiation. The dependence of the technological deformability on the chemical composition of the AlSi7 based alloys and the hydrogen melt treatment regyme was studied using the calculation method for determining the maximum degree of deformation during rolling of wedge-shaped samples.
Results. The regularities of structure formation of the extremely deformed cast aluminum AlSi7 based alloy are determined. The dependences of the structure parameters of the experimental alloy in the cast and ultimate deformed state on the content of modifier elements and the crystallization rate are obtained. A significant increase in the crystal lattice parameter of a-Al in the deformed state compared to the cast state was established for all alloys based on AlSi7, regardless of microalloying and crystallization rate. In a-Al in the deformed state, the solubility of scandium and iron increases. The dependences of the technological deformability on the composition of the AlSi7 alloy and the regyme of hydrogen melt treatment are obtained. An increase in the deformability of the alloy by 60% was established under the complex physicochemical effect of microalloying with strontium and scandium and hydrogen melt treatment for 20 minutes compared to the cast alloy of the initial composition.
Originality. For the first time, regularities of structure formation and formation of a complex of mechanical properties under the combined action of Sr, Sc and the crystallization rate of the ultimate deformed hypoeutectic alloy AlSi7 have been established. The data were obtained for the AK7ch alloy by varying the content of strontium 0…0.2%, scandium 0…0.5% and the cooling rate during crystallization 6.67∙10-4…103 deg/s.
Practical value. In the experiment carried out according to the plan of Orthogonal Latin squares, the composition of the AK7ch alloy was optimized, and a instrument was obtained to influence its structure formation, providing the required level of mechanical properties. A strip 2.4 mm thick was obtained by cold rolling from a billet of AlSi7 (Sr, Sc) alloy with a maximum thickness of 11 mm. The true strain of the AlSi7(Sr, Sc) alloy after hydrogen melt treatment (for 20 min) is 1.19.
Stroganov, G. B. (1985). Vysokoprochnye alyuminievye splavy [High strength aluminum alloys]. Moskva: Metallurgiya, 1985
Kutsova, V. Z., & Aiupova, T. A. (2006). Vliyanie mikrolegirovaniya Sr i Sc na strukturu splava AK7ch [Effect of Sr and Sc microalloying on the structure of the AK7ch alloy]. Stroitel'stvo, materialovedenie, mashinostroenie, 36 (part 1), 201-209
Kutsova, V. Z., Aiupova, T. A., & Ambrazhej, M. Yu. (2007). Vliyanie mikrolegirovaniya Sr i Sc na fazovyj sostav i svojstva AK7ch [Effect of Sr and Sc Microalloying on the Phase Composition and Properties of AK7ch]. Stroitel'stvo, materialovedenie, mashinostroenie, 41 (part 1), 18-30
Taran, Yu. N., Kutsova, V. Z., Koval'chuk, M. G., & Uzlov, K. I. (1988) Struktura i fazovyj sostav siluminov, modificirovannyh stronciem [Structure and phase composition of silumins modified with strontium]. Izvestiya vuzov. Cvetnaya metallurgiya, (3), 78-84
Kutsova, V. Z., Shvetc, O. V., & Ayupova, T. A. (2001). Modifіkuvannya alyumіnієvih splavіv [Modification of aluminum alloys]. "MOM", (1), 99-109
Beresina, A. I., Chuistov, K. V., & Monastyrskaya, T. A. (1999). The stability of structure states of Al-Mg, Al-Li-Mg alloys, alloyed by Sc, Zr and Hf. In: Proc.of the 3rd European Conference on Light Alloys and Composites. Zakopane, (Poland), 43-48
Dobatkina, T. V., Rokhlin, L. L., & Characterova, M. L. (1999). Phase diagrams of the aluminium – base alloys containing scandium. In: Proc.of the 3rd European Conference on Light Alloys and Composites. Zakopane, (Poland), 55-60
Kutsova, V. Z., Elagin, A.S., & Svinarenko, E. I. (2011)/ Struktura i svojstva doevtekticheskih siluminov, modificirovannyh kompleksom Ti-B-Sr [Structure and properties of hypoeutectic silumins modified with Ti-B-Sr complex]. Metaloznavstvo ta termіchna obrobka metalіv. (1-2), 310-318
Kutsova, V. Z., & Elagin, A. S. (2012). Korrozionnaya stojkost' splava AK7ch posle modificirovaniya i termovremennoj obrabotki v zhidkom i tverdom sostoyanii [Corrosion resistance of AK7ch alloy after modification and thermal treatment in liquid and solid state]. Metaloznavstvo ta termіchna obrobka metalіv (2), 40-43
Kutsova, V. Z., & Elagin, A. S. (2012). Vliyanie kompleksnogo modificirovaniya, termicheskoj obrabotki v zhidkom sostoyanii na strukturu i svojstva splava AK7ch [Influence of Complex Modification, Heat Treatment in Liquid State on the Structure and Properties of AK7ch Alloy]. Novini nauki Pridnіprov’ya, (2), 13-16
Shenk, H. (1972). Teoriya inzhenernogo eksperimenta [Theory of engineering experiment]. Moskva: Mir
Dolzhanskyi, A. M., Kutsova, V. Z., Ayupova, T. A., Storozhko, K. D., & Rybkin O. P. (2020). Foundry Aluminium Alloys Cold Rolling. Metaloznavstvo ta termіchna obrobka metalіv, (1), 55-61
Dolzhanskyi, A. M., Ayupova, T. A., Nosko, O. A., Rybkin, O. P., & Ayupov, O. A. (2021). Transition from Engineering Strain to the True Strain in Analytical Description of Metals Hardening. Metaloznavstvo ta termіchna obrobka metalіv, (1), 66-70