EFFECT OF POURING TEMPERATURE AND DEGASSING ON THE CASTING QUALITY OF Al 6061: EXPERIMENTAL AND NUMERICAL STUDY

Abstract

As one of important components of an airplane, body of airplane is required to have high value of strength to weight ratio. In this study, transient heat transfer of Al 6061 in a sand casting process was investigated both experimentally and numerically. The effects of different pouring temperatures (700, 720 and 740 °C) and presence of thin film and H2 inclusions are considered in the present study. Composition, XRD, metallography and tensile strength tests have been carried out to examine the casting product quality, before and after degassing, a process to remove the inclusions from the cast. Correspondingly, heat transfer simulations were carried out by taking into account the variation of pouring temperatures and the presence of inclusions. From the present experimental and numerical study, it was found that: (i) Degassing enhanced significantly the strength of Al 6061 product. The highest tensile strength value has been found to be 64.30 MPa, related to the pouring temperature of 700 °C with degassing, while the lowest one is 35.85 MPa associated with the pouring temperature of 700 °C without degassing . (ii) Pouring temperature did not affect significantly to the strength of Al 6061 product, especially when degassing process was carried out, and (iii) The presence of thin film and hydrogen gas inclusions affected the cooling rate of the metal slab. Overall, the cooling of the metal slab with thin film inclusion became slower, while the cooling of the metal slab with hydrogen gas inclusions became faster.