Abstract

Neutron diffraction is a powerful non-destructive volumetric evaluation method for the analysis of the internal stress state in components processed by laser powder bed fusion (LPBF). High cooling rates and heterogeneous distribution of temperature during additive manufacturing lead to large residual stress fields. Residual stresses developed during the building process have unquestionably an important influence on the mechanical performance and potentially lead to delamination from the support structures, shape distortion but also crack formation. In the present work, neutron measurements have been carried out on cube-shaped samples prepared by LPBF from a Ti-6Al-4V powder bed. A series of miscellaneous positions (center, edge, and corner) over three different depths (close substrate, middle, and close surface) have been analyzed by neutron diffraction so as to systematically characterize the full stress tensor. The influence of shear stresses and second-order residual stresses on the stress tensor analysis is also discussed in this work.

中文翻译：

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用中子衍射测量研究增材制造的Ti-6Al-4V中的残余应力

摘要

中子衍射是一种强大的非破坏性体积评估方法，可用于分析激光粉末床熔合（LPBF）处理的组件中的内部应力状态。增材制造过程中的高冷却速率和温度的不均匀分布会导致较大的残余应力场。毫无疑问，在建筑过程中产生的残余应力会对机械性能产生重要影响，并可能导致与支撑结构的分层，形状变形以及裂纹的形成。在目前的工作中，中子测量是对由LPBF从Ti-6Al-4V粉末床制备的立方体状样品进行的。三种不同深度（靠近基材，中间，并通过中子衍射分析），以系统地表征全应力张量。本文还讨论了剪应力和二阶残余应力对应力张量分析的影响。