ANALISIS SIFAT MEKANIK DAN STRUKTUR MIKRO PADUAN ALUMINIUM ADC12 DENGAN TEKNIK PENGECORAN SEMI SOLID (RHEOCASTING)

Abstract

Aluminum silicon alloys (Al-Si) are generally used in the machine industry because of its superior properties such as;
light weight, good heat conductivity, good casting properties, and good welding properties (Chiang, 2009). Aluminum
die casting 12 (ADC12) is one type of Al-Si alloy with the addition of Cu, Fe, Mn, Mg, Zn, Ti, Cr, Ni, Pb, and Sn
elements. In general, this study aims to find out the comparison of mechanical properties and microstructure of
aluminum alloys before and after stirring. Specific to determine the effect of pouring temperature variation (580, 600,
620, 640, 660, and 680 OC) on fixed rotation and timing (300 rpm, 60 sec) to the mechanical properties and
microstructure of aluminum alloys of ADC12. The research method used is literature study, aluminum alloy preparation
ADC12, equipment of manufacture (melting furnace, stir bar, and metal mold), specimen for tensile test, hardness test,
and microstructure test, specimen test, and analysis of yield data testing with statistical methods. The conclusion of the
research of semi-solid casting of aluminum alloy ADC12 is the difference of mechanical properties of aluminum alloy
ADC12 after the semi-solid casting process with the preparation of slurry without and with stirring. Where there is a
marked improvement in the properties of aluminum alloys ADC12 marks and with stirring. The hardness of aluminum
alloys ADC12 after stirring is higher than before stirring. The highest hardness occurred at 600 OC casting temperature
of 87.9 HB after stirring and lowest at 680 OC at 76.7 HB before stirring. The highest tensile stress with stirring occurs
at a temperature of 600 OC of 235 N / mm2 and the lowest tensile stress at 680 OC casting temperature of 224 N / mm2.
Increased tensile stresses of aluminum alloys ADC12 in the semi-solid casting process are also followed by an increase
in tensile strain. The pouring temperature has no effect on the mechanical properties of aluminum alloys ADC12
because the freezing speed remains the same at different pouring temperatures.