摘要：在机加工过程中，Inconel 718的亚表面常会发生严重的变形和小尺度微观结构的变化，其表层力学性能对部件的疲劳和磨损性能至关重要。因此，从纳米硬度、模量和微观结构变化等方面表征亚表面的力学行为是研究Inconel 718加工性能的关键。由于变形区域面积小，用传统的材料试验方法很难测量该表层的力学性能，利用纳米压痕法可以测量亚表面微尺度下的力学行为（纳米硬度和模量）。在测试中，由于有较多参数，会显著影响测量的可靠性和引起误差，因此本文采用有限元方法研究了压头几何形状对材料弹塑性行为的影响。利用材料幂律模型，模拟压头的叶尖半径和角度等几何参数对Inconel 718的弹塑性响应，采用解析法和数值法相结合的方法确定了Inconel 718的硬度和杨氏模量，并研究了其与叶尖半径和角度的关系。

关键词：纳米压痕；压头形状；亚表层

中图分类号：TG113.25；TH161.2文献标志码：ADOI：10.3969/j.issn.1000-7008.2021.07.010

Effect of Geometry Angle on Mechanical Properties of Inconel 718

 Subsurface Characterized by Nanoindentation

Du Qirui，Yu Miao，Chen Ling

Abstract:The machined subsurface of the white layer often undergoes severe deformation and microstructure changes in a small scale subsurface layer.Mechanical behavior of this shallow layer is critical for component performance such as fatigue and wear，thus characterisation of the mechanical behavior of the machined subsurface in terms of micro/nano hardness，modulus，residual stresses and change of microstructure is vital.Due to the small size of subsurface deformation region，the mechanical behavior of this shallow layer is often hard to measure by using traditional material testing.With the nanoindentation method，mechanical behavior (nanohardness and modulus) at the microscale in subsurface can be measured.In nanoindentation，there are many parameters that significantly affect measurement reliability and thus may lead to errors in the evaluation of results.As the part of project of characterisation of mechanical properties in machined surface by nanoindentation，the indenter geometry effects on elasticplastic behavior is investigated by use the finite element method in present work.As the response to indenter geometry，such as tip radius and angle，the elasticplastic behavior are simulated in the study by use of power law material model.The hardness and the young modulus of the material are determined combining both analytical and numerical methods and their dependence on the tip radius and angle is investigated.

Keywords:nanoindentation；indenter geometry；subsurface