HEAT TREATMENT T4 AND T6 EFFECTS ON MECHANICAL PROPERTIES IN AL-CU ALLOY AFTER REMELT WITH DIFFERENT POURING TEMPERATURES

Untreated alloy in cast-samples showed that hardness increases with increased pouring temperatures, while for samples after heat treatment (T4 and T6), the hardness value decreased with increased pouring temperatures. Ten-sile strength generally increases with heat treatment T4 and T6, but the influence of the temperature on the pouring tensile strength values initially presents high then decreases, then increases again. Impact energy increases after heat treatment T4 and T6. The distribution of precipitates in grain structure results in improved material properties such as hardness, tensile strength, and impact strength compared to when precipitates gathered at the grain boundary.