Powder bed fusion using a laser beam (PBF-LB), one of the most widely adopted additive manufacturing (AM) technologies, fabricates three-dimensional objects by selectively melting and solidifying metal powder through repeated laser irradiation. This technique enables the production of complex components that are difficult to fabricate using conventional subtractive machining. Consequently, PBF-LB facilitates greater design flexibility and enhances manufacturing efficiency.

Conventionally, single-mode fiber laser (SFL) has been employed in PBF-LB systems owing to their superior beam quality and excellent focusing characteristics. However, the laser beam profile of SFL generally follows a Gaussian distribution, where int the beam intensity is concentrated at the center. When such a beam is irradiated onto a powder bed, the localized energy concentration may induce excessive powder evaporation and intense metal vaporization, leading to the generation of spatter. This spattering can cause interlayer defects and increased surface roughness, thereby deteriorate the overall quality of the fabricated parts.

In this study, a flat-top laser beam with a uniform intensity profile was employed to fabricate specimens composed of Ti-6Al-4V (Ti64) alloy. The fabricated parts exhibited a surface roughness of 4 µm, which is significantly lower than the 20 µm obtained using a Gaussian beam. These results show that controlling the laser beam profile is a key factor in ensuring high-quality fabrication in the PBF-LB process.