Actual Problems in Machine Building 2020 Vol. 7 No. 1-2

Actual Problems in Machine Building. Vol. 7. N 1-2. 2020 Materials Science in Machine Building ____________________________________________________________________ 150 21. Прудников А.Н. Поршневые деформируемые заэвтектические силумины // Технология металлов. – 2014.– № 2.– С. 8–11. 22. Афанасьев В.К. Прудников А.Н. Модифицирование бинарного заэвтектического силумина // Известия высших учебных заведений. Черная металлургия. – 1999. – № 10. – С. 33–35. 23. Непрерывное литье алюминиевых сплавов: справочник / В.И. Напалков, Г.В. Черепок, C.B. Махов и др. – М.: Интермет Инжиниринг, 2005. – С. 512. 24. ГОСТ 1583-93. Сплавы алюминиевые литейные. Технические условия / Донецкий государственный институт цветных металлов. – Введ. 1997-01-01. – М.: ИПК Издательство стандартов, 2003. – 24 с. HARDENING OF EARTH CASTINGS FROM BINARY HYPEREUTECTIC SILUMINS Prudnikov A.N. , D.Sc. (Engineering), Professor, e-mail: a.prudnikov@mail.ru Prudnikov V.A. , Ph.D. student, e-mail: vladpr88@gmail.com Siberian State Industrial University, 42 Kirova st. Novokuznetsk, 654007, Russian Federation Abstract The possibility of improving the structure and mechanical properties of binary hypereutectic silumins cast in sand-clay (earthen) forms was studied using the Al-20 % Si alloy as an example. The modifying composition based on phosphorus- and oxygen-containing substances (phosphorous copper, iron oxides) was optimized and the influence of melt processing parameters was determined. It has been established that a decrease in the temperature of the processing of the silumin melt from 900 to 820 ° C makes it possible to reduce the porosity score of castings from 3 to 2. Moreover, the hardening of the castings is not more than 10 %. It is shown that the introduction of a refining reagent into the modifier somewhat reduces the effectiveness of its effect on primary β-Si crystals. Thus, the use of manganese chloride in the modifier increases the size of primary silicon crystals by an average of 25 % in comparison with the modified alloy. However, the elimination of gas porosity in castings from hypereutectic silumin allows to increase their temporary tensile strength by 15–27 % compared with the properties of modified silumin. Keywords hypereutectic silumin, casting, structure, primary crystal silicon, eutectic, hardening.