Actual Problems in Machine Building 2021 Vol.8 N1-2

Актуальные проблемы в машиностроении. Том 8. № 1-2. 2021 Материаловедение в машиностроении ____________________________________________________________________ 77 21. ГОСТ 1583–93. Сплавы алюминиевые литейные. Технические условия / Донецкий государственный институт цветных металлов. – Введ. 1997-01-01. – М.: Изд-во стандартов, 2003. – 24 с. 22. Прудников А.Н., Прудников В.А. Влияние старения на линейное расширение поршня двигателя ЗМЗ 672-11 // European Scientific Conference: сборник статей 9 международной научно-практической конференции. В 2 ч. – Пенза: Наука и просвещение, 2018. – Ч. 1. – С. 32–35. INFLUENCE OF AGING REGIMES ON LINEAR EXPANSION OF LOW-SILICON PISTON SILUMIN 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 Introduction . Currently, alloys of the Al-Si-Cu, Al-Si-Cu-Mg systems (AK5M2, AK5M7, AK12M, AK12MMгН) are used as materials used for the production of pistons for medium-power engines. Silumins, along with satisfactory strength and plastic characteristics, should have, first of all, low thermal expansion and specific gravity. To improve the parameters of piston silumins, it is most advisable to use methods for improving the properties at the final stage of manufacturing parts - final heat treatment. Therefore, the development and optimization of heat treatment modes for piston silumins is an urgent problem. The purpose of the work : to establish the effect of the aging temperature in the range from 100 to 300 °C and the holding time from 3 to 9 h on the average LTEC for the intervals of 20-150, 150-300 and 300-450 °C of the piston cuprous silumin AK5M2. For the study, the pistons were taken, manufactured at the LLC "KMZ" (Naberezhnye Chelny) from silumin alloyed with copper, AK5M2. The research methods were spectral analysis of the chemical composition of piston blanks, dilatometric analysis to determine the LTEC of the samples before and after aging, as well as metallographic studies of the samples in the processed state. Results and discussion . The results of the effect of aging parameters on pistons made of low- silica cuprous silumin AK5M2 for engines of average power ZMZ in the state of delivery are shown. The assessment of the change in the linear expansion of piston silumin AK5M2 after aging in the range of 100-300 °C (after 50 °C) and a holding time of 3 hours over temperature ranges of 20-150, 150-300 and 300-450 °C has been carried out. It has been found that the optimal mode for reducing the expansion coefficient of silumin is a mode that includes aging for 3 h at a temperature of 200 °C. This mode reduces the average LTEC in all intervals of low-medium and high- temperature in comparison with the initial state by 1, 6 and 5.5 %, respectively. In addition, aging of cuprous silumin at temperatures of 100, 150, 200 and 250 °C provides a decrease in LTEC from 1.5 to 7 % in the range of 300-450 °C. It was found that increasing the aging time of the piston alloy sequentially up to 6 and 9 h at 200 °C is not effective. The results obtained make it possible to recommend low-temperature aging at 200 °C for 3 h to reduce the thermal expansion of pistons of engines made of AK5M2 alloy. Keywords alloy, hypoeutectic silumin, piston, aging, linear expansion