Erosion wear characteristics and predictive model of LPBF-fabricated tapered flow channels under solid–liquid two-phase flow

Laser powder bed fusion (LPBF)-fabricated flow channels exhibit significant surface roughness with non-uniform distribution, particularly in overhanging regions where unmelted particles and powder adhesion are prevalent. This study proposes a post-processing method based on solid–liquid two-phase flow erosion wear. By integrating a solid particle–wall collision probability model with a modified E/CRC model, we establish a predictive model for the maximum profile height ( R t ) of LPBF-fabricated tapered flow channels. This model enables engineers to predict surface roughness evolution in real-time during post-processing. Furthermore, this study experimentally investigates and validates the model for LPBF-fabricated Ti6Al4V tapered flow channels. The results demonstrate that the arithmetic average roughness ( R a ) of the flow channels decreases with increasing particle concentration and flow rate. Microstructural analysis confirms wear mechanisms on the flow channel surface are extrusion-induced delamination wear and deformation wear. Solid–liquid two-phase flow erosion wear effectively removes unmelted particles from overhanging surfaces, thereby improving surface quality. The predictive model exhibits excellent agreement with experimental results (accuracy > 88%), providing both theoretical guidance and experimental evidence for optimizing post-processing methods and parameter adjustments of LPBF-fabricated flow channels.