New, application-specific materials are becoming increasingly important in Additive Manufacturing (AM). The number of customized materials that are manufacturable (crack-free) with laser-based AM and/or make targeted use of AM-typical process conditions, such as high cooling rates (up to 10^7 K/s), to achieve specific microstructures and properties is still very limited. To accelerate alloy development, which takes years traditionally, both simulative and experimental approaches have been pursued. Simulations usually cannot predict microstructures of laser-AM fabricated samples accurately because of the high cooling rates. Experimental methods of powder-bed based processes are usually limited to one alloy composition per build job, demanding a high amount of metal powder with the alloy composition and considerable time.
High-speed Laser Directed Energy Deposition (HS DED-LB) has the potential to investigate new material systems quickly and resource-efficiently. In contrast to powder-bed based processes, the alloy composition can be changed within a few seconds and less metal powder is needed for sample production due to the local powder supply. Cooling conditions can be varied over a wide range by adjusting the process parameters, reaching those of the laser-based powder bed fusion (PBF-LB/M).

As of today, the exact relationships between the process parameters in HS DED-LB (e.g. laser power, process speed, powder mass flow, and gas flows) and solidification conditions, microstructural parameters, and mechanical properties are not known. To use the HS DED-LB process for the alloy development of a range of melt-based manufacturing processes (such as PBF-LB/M), these correlations must be determined.

In this work, the first findings on the main factors influencing the HS DED-LB process on solidification cell size (as an indirect means for solidification conditions), hardness, and change in chemical composition due to processing of 316L are presented. The parameters with the greatest influence on the investigated material properties are then explored in more detail.
With the established correlations of process parameters and material properties, HS DED-LB processes can be easily adapted to emulate solidification conditions of other melt-based processes such as PBF-LB/M to accelerate alloy development. Additionally, existing HS DED-LB/M processes can be fine-tuned with regards to desired microstructure, hardness and change in chemical composition more quickly .