This study examines the density, porosity, microstructure, and hardness of aluminum raw materials from used pistons using gravity dies casting and gravity investment casting processes. Gravity die casting and gravity investment casting at a casting temperature of 750°C were employed in this research. Emission Spectrometry is used to determine the chemical composition of a substance (ASTM E-1251). Porosity was measured using macro photography and a digital microscope, with the findings of each mold temperature fluctuation compared. The Rockwell hardness tester is used to determine the hardness of a material (ASTM E-384). A metallographic microscope was used to examine the microstructure of the castings (ASTM E3-11). According to ASTM B-85 standards, this material comprises 71.05% (Al) composition, 13.65% (Si), 7.178% (Cu), 3.4508% (Fe), 1.7870% (Zn), and additional components up to 100%, and is categorized as Aluminum Al-Si (Aluminum-Silicon)A413.0. The density of the test object was calculated using gravity die casting at 2.6972 gr/cm³ and gravity investment casting at 2.6764 gr/cm³. The quantity of porosity impacts the density value, according to the results of porosity observations. The phase (Al) and the phase (Zr) are observed in the microstructure results (Si). In gravity investment casting, the beta phase granules (Si) appear to be larger and fewer. The beta phase granules seem smaller and more abundant in gravity die casting. The hardness value is influenced by the size, number, and dispersion of beta granules. Hardness testing with gravity investment casting yielded a hardness value of 86.84 HVN, according to the results.

This study aims to determine the effect of adding copper powder with different mesh sizes on the welding point, as well as the resulting tensile strength, micro photo and hardness. The raw material of this research is aluminum type 1100. The tests included tensile strength tests (ASME QW-4629 standard), micro photo tests with a metallographic microscope, and Vickers tests (AWS D8.9-97 standard). The results of the tensile strength test rank mesh 40 (556.38), mesh 50 (739.13) and mesh 60 (1316.10) in descending order of tensile strength. The highest value of hardness is in the fusion zone (nugget). The last heat affected zone is in the base metal area and the order of hardness is, in descending order, mesh size 60, 50, and lastly, 40. For micro images, all of the results obtained are the same because they use the same material. The widest melted area in the welding area is on the 60 mesh and it decreases proportionally with the larger meshes.