Pengaruh Perlakuan Panas Terhadap Struktur Mikro Dan Kekerasan Coran Paduan Al-Mg-Si

Abstract

Abstract : The aim of this research is to investigate the effect of the heat treatment to the Al-Mg-Si microstructure and hardness. The material used is from scrapped truck piston. It is melted and poured into the sand mould at 875oC. Then the specimens are made under JIS Z2245 standard for Rockwell hardness testing. The heat treatment is performed by heating the specimens (called solution treatment) in the furnace with temperature variation 5000C, 5500C and 6000C for 30, 60 and 90 minutes respectively. The specimens then are quenched into the water and aged in the air for 5 days. After hardness testing of the specimens, the microstructure investigation is performed by an optical microscope. For each variation, hardness testing is done for 3 specimens. This research indicates that the heat treatment increases the hardness of Al-Mg-Si alloy. At the solution treatment temperature 500oC, 550oC and 600oC for 30 minutes, the average hardness obtained are 77,67, 77,33 and 76 HRC respectively. Meanwhile at the solution treatment temperature 500oC for 30, 60 and 90 minutes, the average hardness obtained are 77,67, 76,67 and 76,33 HRC respectively. From this research, it is concluded that the solution treatment followed by quench and aging can increase the hardness of the Al-Mg-Si alloy. The higher its temperature and longer its process the lower material hardness obtained although it is not so significant.

Keywords : Al-Mg-Si alloy, hardness, solution treatment