WEB Capability of dimensionless enthalpy to describe process limits and boundary conditions in laser powder bed fusion
In the literature on laser powder bed fusion the estimation of process windows is often achieved using energy input calculations. However, most formulas only include process parameters such as laser power or scan speed, while physical properties of the fabricated alloys are not taken into account. Hann et al.  developed an energy equation to describe the melt morphology of laser welded tracks including physical material properties and proved its feasibility to describe the relation of melt pool depth for different materials. Such an equation could as well be beneficial in process development for laser powder bed fusion, especially for new alloys. We investigated the capability of dimensionless enthalpy to describe process boundaries for different materials in laser powder bed fusion. The lower bound enthalpy input is characterized by enhanced surface roughness due to single track instability, while the upper bound is given by the creation of keyhole porosity. The question arises, if those two boundaries can be described by the similar dimensionless enthalpy for different materials. Additionally, in laser powder bed fusion further boundary conditions such as the powder layer and the gas flow within the process chamber have to be taken into account when comparing dimensionless enthalpy relations in contrast to laser welding. In this study we investigated the influence of powder layer thickness, scan line orientation and part placement on process boundaries described by dimensionless enthalpy.