In this post we present the superior mechanical properties of A356 components showing 99.8% relative density  and built on the EOSINT M280.
The A356.0 (AlSi7Mg0.3) SLM specimens built using optimum laser irradiation showed 99.8% relative density, measured by the Archimedes method.
Fine dendritic cell microstructures of sub-micron size (approx. 0.5μm) are observed in the horizontal cross section and elongated cell microstructures along the building direction. They seem aligned with the heat flow. These fine cell microstructures are conventionally found in metal components processed by SLM. They are caused by the rapid melting and resolidification of the material [4-7].
The dense SLM samples exhibit ultimate tensile strength of 400 MPa, yield strength of 200Mpa and breaking elongation values varying between 12% and 17% depending on the build orientation. These values considerably exceed those typically found for cast melting alloys. The superior mechanical properties of the SLM specimens is usually attributed to the high density combined with fine dendritic cell microstructures.
The behaviors of samples manufactured using SLM and the casting is different after heat treatment. After T5 annealing, E% of SLM samples doubled from 15% in the as-built condition up to 30% in the annealed conditions (350 °C). The ultimate tensile strength decreased from 400MPa to 200MPa. The yield strength decreased from to 250MPa to 125MPa, This may be caused by coarsening of the microstructure.
This implies that the mechanical properties of the SLM components could be tailored to suit various applications.
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