Influence of laser beam shaping on process stability, build rate, and microstructure in laser powder bed fusion of AlSi10Mg.

Abstract Laser beam shaping offers promising opportunities to stabilize the laser powder bed fusion (L-PBF) process and improve manufacturing performance. However, most previous studies have focused on shaped beams with spot diameters above 0.2 mm, substantially larger than those conventionally used in L-PBF (< 0.1 mm). Here, we investigate annular and near-top-hat beam profiles with dimensions close to the conventional range for processing AlSi10Mg, using a Gaussian beam as the reference across different optical arrangements with an interlaboratory approach. At moderate laser powers (300–500 W), beam shaping widens the viable power–scan speed (P, V) processing window by delaying the onset of keyhole formation. Compared with the Gaussian beam, the shaped profiles produce shallower and wider melt pools, characterized by higher width-to-depth ratios, while also improving the surface quality of the fabricated parts, as evidenced by lower average roughness ( S a ). Microstructural analysis reveals slightly stronger crystallographic textures for the near-top-hat and annular profiles, whereas the average grain size remains essentially unchanged. Consistently, no clear difference in tensile strength is observed between specimens produced using the near-top-hat and Gaussian profiles. At higher laser power (700 W), the annular beam enables stable processing at scan speeds up to 2.6 m s − 1 , yielding build rates of approximately 20 mm³ s − 1 , about twice those achieved with the Gaussian profile. This productivity gain is attributed to the more stable laser–matter interaction resulting from the lower peak irradiance of the annular intensity distribution. Although the shaped beams generate more spatter, this does not adversely affect the surface roughness of the fabricated parts. These results show that small-sized top-hat, annular, and core/ring beams provide an effective means of extending the stable processing range of L-PBF while improving surface quality and enabling substantially higher build rates.