Akademik Veri Yönetim Sistemi
9th International Aluminium Symposium, İstanbul, Türkiye, 10 - 11 Ekim 2019, ss.256-260
As
with all metallic materials, the mechanical properties of aluminium alloys are
directly related to the microstructure. In both aluminium wrought and casting
alloys, it was observed that mechanical properties increased due to fine and
uniform microstructure during the casting process by applying grain refining
process. By virtue of the fine and equiaxed microstructure, the material shows
high strength and ductility. For these reasons, grain refinement is widely
applied in the casting of aluminium alloys. In the literature; grain refinement
processes can be realized with different methods. These techniques can be
listed as; thermal, chemical and dynamic methods. In this study, orbital
shaking method which lays among the dynamic methods has been investigated.
Within the scope of this study, as an alternative way to the traditional
mechanical vibration method; A356 aluminium casting alloy was cast by lost foam
casting method (LFC) with the orbital shaking. In the experiments, the effects
of the shaking rate were investigated for resulted casting parts. Expandable
polystyrene (EPS) patterns (170x50x40 mm) with the density of 10 kg/m-3 were
used in the moulding process. The castings were performed at 720 °C for 50,
100, 150 and 200 rpm of orbital shaking rate. The reference sample was cast at
static state at the same temperature. The microstructure samples were removed
from the edges and the centre parts of these samples. Metallographic
examinations were carried out via image analyzer assisted optical microscope by
means of calculating shape factor, grain size, and SDAS (secondary dendrite arm
spacing). In addition, the densities of the samples were measured for the
porosity evaluation by Archimedes' principle. The hardness values of the
samples were calculated by Brinell hardness method.