Akademik Veri Yönetim Sistemi
Additive Manufacturing Congress 2026, Antalya, Türkiye, 13 - 15 Nisan 2026, ss.50, (Özet Bildiri)
Powder bed pre-heating is widely employed in additive manufacturing to reduce thermal gradients, residual stresses, and process instabilities; however, elevated temperatures may adversely affect powder morphology, chemistry, and recyclability. This study systematically investigates the influence of laser-based powder preheating temperature and dwell time on the morphological, chemical, and crystallographic evolution of Ti6Al4V powder, using a homogenised defocused diode-laser heating approach representative of in-situ heating strategies in powder bed fusion systems.
Gas-atomised Ti6Al4V Grade 23 powder was subjected to controlled laser preheating at temperatures ranging from room temperature to 1500 °C, with a fixed short dwell time (10 s), alongside an extended dwell-time condition (1 min) at 1200 °C. Powder characteristics were analysed using SEM-EDS, X-ray diffraction, and quantitative image-based particle morphology analysis, including sphericity, roundness, convexity, solidity, and particle size distribution. The practical implications of powder degradation were further validated through multi-layer component fabrication using Diode Point Melting (DPM) with in-situ dynamic laser heating, where surface roughness was evaluated optically.
The results demonstrate that increasing heating temperature induces progressive particle necking, agglomeration, and coarsening, accompanied by a gradual reduction in sphericity and roundness. Aluminium depletion due to preferential vaporisation becomes evident above 800 °C, while partial α→β phase formation is observed at elevated temperatures, particularly when prolonged dwell times are applied. Extended laser–powder interaction time was found to exert a stronger influence on morphological degradation and phase evolution than temperature alone. Although high-temperature laser preheating does not lead to severe powder-cake formation typically associated with electron beam processes, excessive temperature or dwell time degrades powder flowability and increases surface roughness in fabricated components.
These findings highlight the critical trade-off between thermal stabilisation benefits and powder degradation risks, providing quantitative guidance for optimising laser-assisted preheating strategies in powder bed fusion while preserving powder reusability and part surface quality.