چكيده به لاتين
The lattice structure is a subset of metallic cells, whose unit cell is regularly repeated in three dimensions. The difference between these materials and stochastic metallic cell, such as metallic foam, is that their properties are predictable. In this research, to study the effects of the casting parameters on the mechanical properties of the lattice structures, a cubic unit cell repeated in three dimensions was used. Aluminum alloy 413 was used due to its high fluidity in this study. Initially, the model was constructed by additive manufacturing process using a FDM three-dimensional printing machine. After molding, the centrifugal casting was used for filling the mold. This is a combination of investment casting and centrifugal casting to produce low thickness specimens. This method is also called semicentrifugal casting. In order to investigate the effect of cell size, the ratio of length/ cell truss thickness for specimens were 20 and 30. By increasing this ratio, the melt fluidity decreased and therefore filling the mold was difficult. On the other hand, increasing the ratio, reduces mechanical properties. Among the casting parameters, the preheating temperature of the mold and the rotation time of the centrifugal machine were selected. The effect of two different temperatures of 500 and 600 °C, and three rotation times of 30, 90 and 180 seconds on filling and mechanical properties were studied. Based on the results obtained, preheat temperature of 600 °C and rotation time of 180 seconds exhibited the optimized conditions. The highest compressive strength of 62 MPa was resulted from the specimen cast into the mold preheated at 600 °C with a rotation time of 180 seconds and the ratio of 20. However, the strength of specimens cast into the mold preheat at 500 °C and rotation times of 90 and 180 seconds were 40 and 58 MPa, respectively. The compressive strength for the specimen with a length to thickness ratio of 30 was constant and was 19 MPa. Comparison of the results shows that increasing the thickness of the sections, the mold temperature and the rotational time, result in increasing the compressive strength.
