Dual-laser powder bed fusion using 450 nm diode area melting and 1064 nm galvo-scanning fiber laser sources

This study introduces an innovative dual laser powder bed fusion (PBF-LB/D) system, which combines two distinct laser processing methods to enhance control over microstructural outcomes. Unlike conventional PBF-LB systems that employ a single laser type, this dual-laser setup integrates a traversing Diode Area Melting (DAM) laser head with multiple 450 nm diode lasers (4 W each) and a traditional high-power (200 W) 1064 nm fiber-laser. This unique configuration allows for significantly different melt pool solidification rates within the same layer. For the first time, Ti6Al4V feedstock was processed using both laser types within a single sample. A specific scanning strategy defined separate laser processing regions, including an overlap where both lasers interacted to fuse the feedstock and bridge the two regions. The fiber-laser melted (FLM) regions experienced much higher cooling rates (∼107 °C/s) than the DAM regions (∼600 °C/s), resulting in acicular ά/α phases. In contrast, DAM regions exhibited larger grains, with parent β grain sizes approximately 13 times larger than those in the FLM zone. This dual laser system investigation not only demonstrates microstructural in-situ spatial tailoring but also highlights variations in the laser-induced heat-affected zone, surface roughness, and mechanical properties across different regions within the fabricated Ti6Al4V samples.