Abstract:

In order to assess the process of accumulation of damages in billets obtained by casting in sand molds, studies of castings made from an aluminum alloy are conducted. Analysis of the physical heterogeneity of the material is carried out on the basis of the microstructural studies, as well as the LM hardness method. It is shown that it is expedient to evaluate the technological damageability of various zones of cast billets with complex spatial geometry that contain massive thermal assemblies and thin walls, according to the dispersion degree of the hardness characteristics. The technological damageability of billets obtained in sand molds varies widely and mainly depends on the conditions of crystallization of their individual volumes: – distribution of temperature fields; – direct heat reducing; – features of the metal feeder with a liquid phase during crystallization. The influence of the mold design on the formation of technological damage is analyzed. Increasing the distance from the feeder promotes growth, and accelerated crystallization and directed heat removing promote reduce in technological damage to the volume of the casting when cured. Damageability of the material of cast billets serves as a parameter that is quantitatively evaluates the reliability characteristics of products, and its definition allows to formulate new approaches to the selection of foundry alloys and improve casting technologies to increase their operational durability. On the basis of the conducted studies it is established that the technological damageability is 1.3–6.5 times higher than for the base material in the near-surface layer at a depth of 2 mm. Author Biographies Oleg Kuzin, National University «Lviv Polytechnic», 12, S. Bandera str., Lviv, Ukraine, 79013 PhD, Associate Professor Department of Applied Material Science and Materials Engineering

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