Effect of heat treatments and loading orientation on the tensile properties and fracture toughness of AlSi7Mg alloy produced by Laser Powder Bed Fusion

The present study investigates the effect of building orientation and heat treatment routes on the mechanical behavior of the AlSi7Mg alloy (A357) produced by Laser Powder Bed Fusion. The microstructure and mechanical behavior of A357 in the as built, T5 (directly aged) and T6 (solution treated, water quenched and aged) conditions were compared. Tensile properties of the material were evaluated along two main directions (parallel and normal to the building platform), whereas fracture toughness was measured with cracks placed in three orthogonal orientations. The results indicate that the anisotropy in mechanical properties is greatly reduced after T6 temper, but the selection of the best condition between the as built, T5 and T6 temper must consider the main loading directions and possible crack growth orientations associated with the specific application.