Numerical Investigation into the Dynamics of Ti-6Al-4 V Alloy Molten Pool by Annular Laser Beam

Laser powder bed fusion (LPBF) offers significant advantages in manufacturing precision and performance, with broad application prospects. However, component quality can be easily compromised during the process, resulting in defects such as pores and spatter, which are influenced by factors like laser parameter settings. Traditional Gaussian laser beams commonly used in LPBF create deep keyholes and localized overheating, leading to residual stress buildup and structural instability. This study employs numerical simulation to compare the melt pool dynamics of annular and Gaussian beams in Ti-6Al-4 V processing. A multiphysics coupling model simulates melt pool evolution, temperature distribution, and flow behavior under annular beam irradiation, revealing that the annular beam induces a ‘secondary heating’ effect. In this study, the annular beam’s unique energy distribution pattern was shown to mitigate the steep thermal gradients and localized overheating characteristics of Gaussian beams, which are known to induce unstable keyhole dynamics and porosity. The multiphysics model revealed that the annular beam’s secondary heating effect promotes a more uniform temperature field and melt pool shape, reducing the likelihood of keyhole collapse and defect formation. This is particularly critical for Ti-6Al-4 V, where even minor thermal stress variations can compromise its excellent fatigue resistance and biocompatibility. The findings align with previous research indicating that optimizing laser beam profiles can significantly expand the process window and improve material properties.