In this work, experimental and numerical approaches are performed to explore the influence of scanning strategies on the microstructure, crystallographic texture as well as the mechanical behavior of Ti-6Al-4V alloy manufactured by Laser Powder Bed Fusion (LPBF). In-situ monitored data of the energy intensity show that different scanning strategies result in variations of energy intensity distribution. The characterization of the microstructure and crystallographic texture reveals that the sample with hexagon scan pattern displays the structure with columnar primary β phase, while the specimens with chessboard scan exhibit equiaxial-like morphology. EBSD and TEM results provide evidence of the appearance of residual β nanoparticles. A finite element model is developed to further explain the phase transformation during LPBF and the formation mechanism of residual β particles. The numerical results indicate that the appearance of the residual β phase is attributed to the preheating/reheating effect by the adjacent tracks and successive layers, and the final phase composition of the LPBF-built Ti-6Al-4V alloy combines the α′, α, and β phases. Findings in the present paper show that various scanning strategies lead to a clear diversification in the microstructure, crystallographic texture, and phase composition of LPBF-built samples, which opens a route towards the tailoring of mechanical properties and isotropic behaviors in additive manufacturing.

在这项工作中，通过实验和数值方法来探索扫描策略对激光粉末床融合 (LPBF) 制造的 Ti-6Al-4V 合金的微观结构、晶体织构和机械行为的影响。能量强度的原位监测数据表明，不同的扫描策略导致能量强度分布的变化。微观结构和晶体织构的表征表明，六边形扫描样品显示具有柱状初级β相的结构，而棋盘扫描样品显示出类等轴形貌。EBSD 和 TEM 结果提供了残留 β 纳米粒子出现的证据。建立有限元模型以进一步解释LPBF过程中的相变和残余β粒子的形成机制。数值结果表明，残余β相的出现归因于相邻轨道和连续层的预热/再加热效应，LPBF构建的Ti-6Al-4V合金的最终相组成结合了α'、α , 和 β 相。本文的研究结果表明，各种扫描策略导致 LPBF 构建样品的微观结构、晶体结构和相组成明显多样化，这为增材制造中的机械性能和各向同性行为的定制开辟了道路。数值结果表明，残余β相的出现归因于相邻轨道和连续层的预热/再加热效应，LPBF构建的Ti-6Al-4V合金的最终相组成结合了α'、α , 和 β 相。本文的研究结果表明，各种扫描策略导致 LPBF 构建样品的微观结构、晶体结构和相组成明显多样化，这为增材制造中的机械性能和各向同性行为的定制开辟了道路。数值结果表明，残余β相的出现归因于相邻轨道和连续层的预热/再加热效应，LPBF构建的Ti-6Al-4V合金的最终相组成结合了α'、α , 和 β 相。本文的研究结果表明，各种扫描策略导致 LPBF 构建样品的微观结构、晶体结构和相组成明显多样化，这为增材制造中的机械性能和各向同性行为的定制开辟了道路。