Geometric characteristics of AlSi10Mg ultrathin walls fabricated by selective laser melting with energy density and related process parameters

In applications requiring large specific surface area, ultrathin walls fabricated by selective laser melting (SLM) have attracted wide attention. Understanding that the geometric characteristics of ultrathin walls are affected by process parameters is an important topic. To investigate the influence of SLM process parameters on geometric morphology, interlayer banding characteristics, and defects of the AlSi10Mg ultrathin walls, based on the normalized processing map, the multi-layers and single-track SLM tests under different energy density and interlayer cooling conditions were implemented. The ultrathin walls with the width between 100 μm and 450 μm were successfully fabricated in the range of single-track energy density between 5 and 30, and their geometric morphology and interlayer banding characteristics are not significantly affected by the interlayer cooling time. Except that the height of thin walls does not change significantly with the process parameters, the width, penetration depth, and cross-sectional area of molten pool all have a power function decreasing relationship with the scanning speed, and all have a linearly increasing relationship with the laser power and single-track energy density, respectively. The macroscopic banding distance decreases linearly with the increase of laser power and single-track energy density and decreases exponentially with the decrease of scanning speed. When the single-track energy density is about 5 and 25, it is easier to obtain a more uniform banding distance close to the standard preset layer thickness under high power (≥ 300 W) with lower scanning speed (≤ 0.589746 m/s). The process parameter combination of high laser power (≥ 300 W) and low energy density (E* = 5) contributes to obtaining ultrathin-walled structures with the narrowest width of about 100 μm. Within the range of single-track energy density of 10 to 20, the use of appropriate laser power and scanning speed can be expected to avoid “necking,” “keyhole pore,” and “cracking” defects. This work provides guidance for choosing reasonable SLM process parameters when fabricating ultrathin walls in practical engineering applications.