Classical Solidification Structures in Single-Step Metal Additive Manufacturing

Single-step additive manufacturing (AM) techniques, such as powder-bed fusion and directed energy deposition, paved the way for the direct fabrication of ready-to-use parts. The understanding of the as-built microstructure and the access to it through the fabrication process can be problematic, since multiple alterations occur simultaneously or in quick succession. This chapter serves to pick the individual steps apart and to explain these one by one, thereby showing the correlations to fundamental knowledge from the well understood classical processes of welding and casting. Typical microstructural development is exemplified by the examples of the austenitic stainless steel 316L and the age-hardenable hypoeutectic AlSi10Mg alloy. Both have been widely studied in the AM community and are widely used nowadays, representing ideal examples to show the correlation of macroscopic mechanical properties and the as-built microstructure.