In the present work, several large Ti–6Al–4V blocks were successfully fabricated by high-power laser metal deposition (HP-LMD). The high cycle fatigue (HCF) property and fatigue crack growth (FCG) behavior of the as-build Ti–6Al–4V alloy were investigated from two sampling directions (horizontal and vertical). The results showed that the fatigue limit of horizontal and vertical specimens was 357.5 MPa and 358.57 MPa, respectively. However, the HCF performance of vertical specimens was superior to horizontal specimen under a high-stress level. In addition, the HCF performance of both horizontal and vertical specimens was inferior to the wrought Ti–6Al–4V. Meanwhile, the FCG rate of vertical specimen was lower than that of horizontal specimen in both near-threshold region and Paris region. The anisotropic microstructure (prior β columnar grains with preferential orientation and α colonies) was found to be the main reason that contributed to an anisotropic HCF property and FCG behavior. For horizontal specimen, the fatigue crack interacted with only one or two columnar grains, thus leading to a lower FCG resistance. For vertical specimen, the fatigue crack interacted with multiple columnar grains, which led to a better plasticity and enhanced FCG resistance.

在目前的工作中，通过高功率激光金属沉积 (HP-LMD) 成功制造了几个大型 Ti-6Al-4V 块。从两个采样方向（水平和垂直）研究了初始 Ti-6Al-4V 合金的高周疲劳 (HCF) 性能和疲劳裂纹扩展 (FCG) 行为。结果表明，水平和垂直试样的疲劳极限分别为357.5 MPa和358.57 MPa。然而，在高应力水平下，垂直试样的 HCF 性能优于水平试样。此外，水平和垂直试样的 HCF 性能均不如变形 Ti-6Al-4V。同时，近阈值区和巴黎区垂直试样的FCG率均低于水平试样。发现各向异性微观结构（具有优先取向和 α 菌落的先前 β 柱状晶粒）是导致各向异性 HCF 性能和 FCG 行为的主要原因。对于水平试样，疲劳裂纹仅与一个或两个柱状晶粒相互作用，从而导致较低的 FCG 抗力。对于垂直试样，疲劳裂纹与多个柱状晶粒相互作用，导致更好的塑性和增强的FCG抗力。