The effect of adding local salt as cover flux on the porosity and mechanical properties of the casting of aluminum alloys AC3A

Research on the effect of adding a cover flux made from local salt to the porosity and mechanical properties of the AC3A aluminum alloy casting has been carried out. In this study, cover flux was made by utilizing domestically sourced salt with other supporting materials, such as sodium sulfate, sodium nitrate, and sodium silicon fluoride. The stages of making cover flux include sieving, mixing, heating, drying, and second sieving. Characterization of SEM, EDS, DSC, Specific Gravity Testing, and XRD were carried out on the cover flux samples that had been made, showing the processes and products that produced an effective reaction and could be applied to aluminum casting. Then the cover flux sample that has been added to the AC3A aluminum casting, after that characterization of the casting results is carried out. OES characterization shows the type of aluminum used for research is Aluminum AC3A. After that, porosity testing was carried out with the OSTEK Porosity Tester, which showed a decrease of porosity percentage in the AC3A casting results. The addition of cover flux made from local salt in AC3A casting was able to reduce the percentage of porosity by 60.3% at a pouring temperature of 620oC and by 62% at a pouring temperature of 660oC. The casting process is carried out in a crucible furnace with a metal mold SKD 61 to obtain tensile test specimens and impact tests. The addition of cover flux can increase the Ultimate Tensile Strength value by 6.5% at a pouring temperature of 620oC and by 8% at a pouring temperature of 660oC. The addition of cover flux can increase the Impact Strength value by 31.6% at a pouring temperature of 620oC and by 53.8% at a pouring temperature of 660oC.