随着增材制造（AM）技术向工业化应用迈进，受限于AM合金独特的组织、缺陷特性及部件结构/尺度的限制，基于微试样对其力学性能开展有效、科学的认证与评价的方法变得尤为迫切。本研究通过对不同厚度的微试样进行拉伸和悬臂梁弯曲实验，研究了试样厚度与晶粒尺寸的比值（t/d）对AM技术制造的GH3536合金力学性能的影响。结果表明，随着t/d的增加，合金的抗拉强度、均匀伸长率及疲劳寿命均先逐渐增大后趋于平稳。结合实验结果及有限元分析，确定了悬臂梁型微试样弯曲疲劳测试的临界尺寸，即保证t/d ≥ 5.0。基于此临界尺寸合理选择微试样厚度有助于提高AM部件力学性能评价的稳定性和准确性，从而为疲劳性能评估提供更加可靠和可行的方法。

As additive manufacturing (AM) technology advances toward industrial applications, constrained by the unique microstructure and defect characteristics, and structural/dimensional limitations, it has become particularly urgent to develop effective and scientific certification and evaluation methods based on miniature specimen for mechanical properties of AM component. In this study, the effect of specimen thickness to grain size ratio (t/d) on the mechanical properties of the GH3536 alloy fabricated by AM technology were investigated by using miniature specimen with varying thicknesses conducted on tensile and cantilever beam bending fatigue tests. The results show that as t/d increases, the tensile strength, uniform elongation, and fatigue life of the alloy first increase significantly and then stabilize. Combined experimental results and finite element analysis, the critical dimension of miniature specimen using for cantilever beam bending fatigue tests was established, ensuring that t/d ≥ 5.0. Reasonable selection of miniature specimen thickness based on this critical dimension contributes to improve stability and accuracy in mechanical property evaluation of AM components, thereby providing a more reliable and practical approach for fatigue performance assessment.